1 r J> • _ ft ;■}'•• . umm* + Of THE UNlVEtSftV Of ■sytm* WAR DEPARTMENT BASIC FIELD MANUAL VOL. IV SIGNAL COMMUNICATION ILLINOIS BASIC FIELD MANUAL VOL. IV SIGNAL COMMUNICATION PREPARED UNDER THE DIRECTION OF THE CHIEF SIGNAL OFFICER FEB 15 1932 UNIVERSITY OF ILLINOIS. UNITED STATES GOVERNMENT PRINTING OFFICE WASHINGTON : 1931 For sale by the Superintendent of Documents, Washington, D. C. Price 50 cents WAR DEPARTMENT, Washington, April 6, 1931. Basic Field Manual, Volume IV, Signal Communication, is published for the information and guidance of all concerned. [A. G. 062.11 (5-7-30).] By order of the Secretary of War: DOUGLAS MacARTHUR, General, Chief of Staff. Official: C. H. BRIDGES, Major General, The Adjutant General. II Ti Un. Am ■ • . ■ . r- -. -n : • / ; ' ...... ... .X20tll . BASIC FIELD MANUAL, VOLUME IV SIGNAL COMMUNICATION (This pamphlet supersedes paragraphs 3, 8, 9, 14, 16, 18-21, 24, 25, 27-30, and 32 and Sections V, IX, X, and XI, TR 160-5, June 28, 1929; TR 160-6, June 29,1929; TR 160-10, June 28, 1929; Sections II, III, and IV and paragraphs 27-29, TR 162-5, April 20, 1926; and TR 163-5, October 1, 1929.) CHAPTER 1 GENERAL Paragraphs Section I. Objective of this and other texts relating to signal communication_ 1-2 II. Staff duties of signal communication officers _ 3-5 III. Organization for signal communication_ 6-9 Section I OBJECTIVE OF THIS AND OTHER TEXTS RELATING TO SIGNAL COMMUNICATION 1. Objective of this text. —This text includes signal reg¬ ulations and technical information needed by officers and enlisted men of arms other than the Signal Corps engaged in signal com¬ munication. It supplements the matter contained in chapter 7, Basic Field Manual, Volume VIII, and prescribes in detail the installation, maintenance, and operation of signal communica¬ tion agencies which are employed at and forward of brigade headquarters. 2. Other official texts relating to signal communica¬ tion. — a. Chapter 7, Basic Field Manual , Volume VIII , includes information of signal communication required by officers of all arms whether or not on communication duty. This chapter prescribes general principles and methods which apply to the signal communication systems of all units. b. Signal Corps Field Manual gives information relating to systems and services handled by Signal Corps personnel. The Signal Corps Field Manual supplements this manual (B. F. M., Vol. IV) and covers systems, equipment, and methods of greater 1 2 BASIC FIELD MANUAL technical complexity than those used at and forward of brigade headquarters. The Signal Corps Field Manual is ordinarily required by Signal Corps personnel only. c. Technical Regulations give technical information and detailed description of communication equipment. At present this in¬ formation is published as training, wire communication, and radio communication pamphlets. When reprinting is necessary, however, these pamphlets will be renumbered in the Technical Regulations series. d. Training Manuals describe methods of training signal com¬ munication specialists. Section II STAFF DUTIES OF SIGNAL COMMUNICATION OFFICERS 3. Communication officer member of staff.—The unit signal or communication officer is a member of the staff of his commanding officer. He is responsible to his commanding officer that both tactical and technical control of signal communication are properly exercised throughout the command. This control is exercised, upon the approval of his commander, through the normal channels of command, except that technical control over routine matters may be exercised directly among the signal or communication officers concerned. 4. Responsibility for signal communication.—The re¬ sponsibility for signal communication, being a function of com¬ mand, can not be delegated by the commander. However, each commander is provided with a member of his staff who is trained as a specialist in signal communication, and this staff officer is charged with the execution of all command functions pertaining to signal communication, under such restrictions as may be pre¬ scribed bj r the commander. This officer is called the signal officer or the communication officer. In this manual the term “signal officer” will be used irrespective of the name applied to this officer by Tables of Organization. It should be noted that two channels are utilized in securing control over signal communica¬ tion. All orders affecting the tactical employment of agencies of signal communication are issued through the normal channels of command and are coordinated with orders issued to other tactical or technical agencies by the appropriate staff section prior to issue. But orders which are issued for the technical BASIC FIELD MANUAL 3 control of an agency of signal communication in routine matters, which do not need coordination with orders issued to other elements of the command, may be issued in the name of the commander, direct by the signal officer of the superior unit to the signal officers of subordinate units. The employment of the direct channel by signal officers depends upon the relation exist¬ ing between the individual commander and his signal officer. In well-trained organizations only those matters which need coor¬ dination with other than signal activities follow the normal channels of command. All purely signal communication activ¬ ities are controlled by the signal officers concerned, in accordance with the general policies prescribed by the commander. The above principles govern the method of issuing orders to signal communication troops of subordinate units by unit signal officers. The unit signal officer must first secure the approval of his commander to all plans for signal communication prior to their issue in the form of orders. The approval of the com¬ mander is secured by one of three methods: a. Routine matters are covered by general policies promul- . gated by the commander. b. Plans for furnishing signal communication wffiich affect functions which have been delegated to other staff sections are approved by the chief of the staff section concerned. c. Plans for furnishing signal communication maj^ be approved by the commander in person. 5. Duties of unit signal officer.—The general duties of the unit signal officer may be divided under two headings: a. Duties during training periods .—During training periods the unit signal officer— (1) Prepares the training programs for signal communication troops of his unit and lower units under the general policies laid down by his commander and by higher authority. (2) Organizes and supervises such specialists’ schools as may be authorized by his commander or required by orders of higher authority. (3) Makes such inspections of the signal communication per¬ sonnel and equipment of his own and subordinate units as his commander may direct or authorize and submits recommenda¬ tions to the latter concerning action that should be taken to cor¬ rect deficiencies that may exist or to improve training methods or doctrines. 4 BASIC FIELD MANUAL (4) Takes steps to secure and supply ample training and organ¬ izational signal equipment throughout the command. (5) Prepares such orders, regulations, and signal operation instructions as may be needed for the efficient training of the signal communication personnel of the command. (6) Personally conducts the training and secures the training and organization equipment for the signal communication troops of his unit in brigades and smaller units. b. Duties during combat or under simulated combat conditions .— During combat or under simulated combat conditions he— (1) Prepares or secures from higher authority such orders and signal operation instructions as may be needed to insure the technical and tactical control of the signal communication sys¬ tems of his unit. He insures the proper distribution of such orders and signal operation instructions throughout his unit. (2) Acts as technical adviser to his commander and his staff on all matters pertaining to signal communication. (3) Submits recommendations as to the location of the axes of signal communication and command posts of each subordinate unit and of his own unit when not prescribed by higher authority. (4) Prepares the plans for the employment of the signal com¬ munication agencies of his own and subordinate units so as to insure the most efficient employment of these agencies at his own command post and the necessary coordination and technical control of the agencies of subordinate units, subject to orders received from higher authority. He submits these plans to his commander or appropriate staff officer for approval. (5) Prepares all orders to signal communication troops based upon the approved plan and insures the promulgation of these orders. (6) Supervises the signal communication systems employed by * his own and subordinate units, to correct deficiencies and secure coordination between systems during combat. (7) Takes steps to procure and supervises the replacement of signal equipment and personnel of his own and subordinate units. Section III ORGANIZATION FOR SIGNAL COMMUNICATION 6. Division of duties. —Signal communication within brigades and smaller units is conducted by the personnel of the unit con¬ cerned. Other signal communication is handled by the Signal BASIC FIELD MANUAL 5 Corps. Provision is made in the organization and equipment of each unit for the conduct of its own communication. 7. Communication agencies. —The principal communication systems relied upon are messenger, wire, and radio, but visual and acoustic signaling are used for special purposes. It is unwise to rely upon one means to the exclusion of others, because special circumstances may make that preferred system inoperative when communication is urgently needed. Communication units are therefore organized for the operation of the several agencies ap¬ propriate to the special needs of the unit concerned. 8. Each unit system a part of a larger system. —By the organization outlined above there are in a large tactical unit many small communication systems each installed, maintained, and operated by personnel of a separate unit. Each of these systems, however, is so conducted as to form a part of the general system so that messages may be transmitted rapidly and effi¬ ciently from one headquarters to any other headquarters in the system. Economy of equipment and labor frequently requires that a system installed by one unit be turned over to another. It is evident therefore that there should be uniform methods of pro¬ cedure and construction throughout all units. 9. Cooperation between communication units. —To insure successful signal communication the communication troops must work as a team regardless of arm or service. There should exist a spirit of mutual helpfulness and cooperation. Personnel of ad¬ jacent units should take every suitable opportunity to become personally acquainted, to understand the special problems and conditions in neighboring systems, and to offer such assistance and cooperation in the solution of difficulties as may be practi¬ cable. CHAPTER 2 FIELD WIRE SYSTEMS Paragraphs Section I. General_ 10-22 II. Technique of field wire line construction_23-42 III. Installation and operation of telephones and centrals_43-66 IV. Installation and operation of field telegraph sets and stations_ 67-70 V. Maintenance of field wire systems_71-86 Section I GENERAL 10. Purpose and scope.— The purpose of the following instructions is to standardize the installation, maintenance, and operation of the field wire systems of tactical units of the different arms. This standardization is necessary in order to secure more efficient signal communication service for the Army. The term “signal” as used in this manual applies to all personnel, units, or agencies employed in signal communication work. In providing methods of technique, a standard practice is prescribed, disre¬ garding the individual duties assigned to the personnel of signal communication units. These duties are specifically explained in the training publications pertaining to the different arms and tactical units. 11. Composition of wire systems.— a. The wire system of a tactical unit consists of the telephone and telegraph commu¬ nication normally installed and operated by the signal personnel assigned to the headquarters of such a unit. The collective wire system of a tactical unit comprises its own wire system and the wire systems installed and operated by all subordinate units. For example, the division wire system includes only the wire communication installed and operated by the division signal company or troop, whereas the collective division wire system includes its own wire system and all other wire communication installed and operated within the division by subordinate units. b. A wire system includes all means of signal communication utilizing wire lines. From the viewpoint of materiel, it consists 6 BASIC FIELD MANUAL 7 of wire circuits, connecting and operating equipment, and certain special apparatus for testing the circuits. c. A general classification of wire circuits is made according to their use, as follows: (1) Trunk circuits, which connect telephone centrals. (2) Local circuits, which connect telephones to centrals or other telephones. d. A further special classification of wire circuits is made according to the number of physical wires used in the circuit: (1) Metallic circuits, in which two wires form a complete path for the electric current. (2) Ground return circuits, in which one wire is used, with the earth taking the place of the second wire. Of the two circuits the metallic has proved to be the more satisfactory. It is less susceptible to interference from other circuits, earth currents, or conversation interception by hostile listening stations. The communication range may, however, be usually increased by the use of a ground return circuit. e. Additional special circuits may be derived from these me¬ tallic circuits by the use of repeating coils, as follows: (1) A single metallic circuit may provide both a telephone and a telegraph circuit without mutual interference. This type of telegraph circuit uses a ground return and is known as a simplex circuit. (.2) Two metallic circuits may provide a third telephone or telegraph circuit without interference from one another. This third circuit is known as a phantom circuit. /. Connecting and operating equipment includes telephone and telegraph instruments, switchboards and auxiliary supplies. g. Testing apparatus includes telephone and telegraph in¬ struments and special test sets. 12. The telephone; powers and limitations.— a. The greatest advantage of the telephone is that it affords immediate personal contact between two individuals. Disadvantages of the telephone are the lack of record of the conversation, and the tendency to consume too much time in conversation. 6. The efficiency of the telephone system depends upon a number of factors, the most important of which are— (1) Type of wire line construction. (2) Types of telephones, switchboard, and other equipment. (3) The weather. 8 BASIC FIELD MANUAL (4) The training of the personnel operating and using the system. c. The distance over which telephone conversation is possible is limited by the electrical characteristics of the complete tele¬ phone circuit. A given type of wire circuit, under normal con¬ ditions, has a definite talking range. The wire factors which increase the talking range are— (1) Better electrical conductivity of the material of which the wires are made. (2) Larger diameter of the wire. (3) Greater spacing between w r ires and between wires and ground, within certain limits. (4) Better electrical insulation between wires and between wires and ground. The converse of these factors decreases the range of telephone conversation. d. The following conditions tend to decrease the efficiency of telephone circuits and the range of telephone conversation: (1) Snow, ice, rain, heavy dew, or fog. (2) Moisture in the telephone instrument, especially in the transmitter. (3) Exhausted dry batteries in local battery (magneto) telephones. (4) Additional telephones (party line). (5) Additional switchboards. 13. The telegraph; powers and limitations. —The wire telegraph is one of the most rapid and accurate electrical means of transmitting messages. The simultaneous transmission of telephone conversations and telegraph messages over the same circuit is common practice. The ranges of telephone and tele¬ graph circuits are limited by the same factors. Most telegraph instruments have a much greater range than telephones over a given circuit. A failure to utilize telegraph channels over¬ burdens the telephone system. 14. Wire communication during movement of com¬ mand posts. —The maintenance of wire communication is usually more difficult during the movements of command posts than at any other time. The initial installation of each wire system should be planned with the objective in view of main¬ taining continuous wire communication with subordinate units during and after the movement of command posts. A satis¬ factory solution in any given situation is normally a combination of the general methods described below. BASIC FIELD MANUAL 9 a. Single-axis method .—In Figure 1 (for a description of symbols see par. 20), assume that the command post of a unit is located at 3 and that the command posts of its subordinate units are at 1 and 6, respectively: The axes of signal com¬ munication of these units are 3-5, 1-2, and 6-7, respectively. The superior unit runs one circuit from 3 to 1 via 4 and another circuit from 3 to 6 via 4. Prior to the movement of the com¬ mand posts of the subordinate units to 2 and 7, respectively, two circuits are run by the superior unit from 4 to 5, one circuit is continued from 5 to 2 and the other circuit from 5 to 7. When the command post of the* subordinate unit at 6 moves to 7, the 3-4-6 circuit is used until the moment the command post closes □ P 7 o ( subordinate) UNIT j 2 . ( 3UBORDI NATE) UNIT J P 7 9 /subordinate) \ UNIT ]

Tags may also be desirable along the wire route, especially at points where the type of construction changes, as from surface to overhead. 28. Terminal strips. —A terminal strip comprises a block of insulating material to which is fastened a number of binding posts or stud bolts with washers and nuts. The binding posts are connected in pairs by metal strips, so that a wire connected to a binding post on one side will be joined electrically to another wire connected to the opposite post. Terminal strips are now issued in several styles. The type TM-84 (fig. 26) is provided with 10 through connections and will handle five pairs of wires. The connections are made by means of wing-nut binding posts fitted with a washer and skinner lug. The skinned wire is connected by plac¬ ing the wire in the skinner lug and around the bolt under the washer in the direction that the wing nut tightens, then back through the skinner lug. The protruding end of the wire is cut off. The wing nut is then tight¬ ened. The type TM- 84—A (fig. 27) is also a 5-pair terminal strip and differs from the TM-84 only in the structure of the binding posts. 29. Wire laying equipment. — a. Field wire is carried for¬ ward and laid by any one of the following means, depending upon the condition of the roads and terrain, traffic •conditions, and character of hostile fire: Motor trucks; specially constructed horse and motor-drawn carts and reels; escort wagons; reel carts, hand drawn or towed behind communication carts; pack reels; breast reels; spools or coils carried by hand. TL-708 Figure 23. —Marline tie to a metal support TL-709 Figure 24.—Marline tie to a knob BASIC FIELD MANUAL 33 TL-7/0 Figure 25- -Circuit marking tag b. If issued on wooden spools, wire may be laid by inserting an iron bar through the axial opening in the spool and paying off from the spool, or the wire may be rewound onto a spool of spe¬ cial design used with a horse or motor-drawn cart or reel, reel cart, breast reel, or pack reel. (1) Motor trucks are used for laying wire but no special design exists for this purpose. The wire is either paid off from the spool as issued, or from a pay-out reel of commercial or improvised type. This method is ap¬ plicable where the route lies along a hard-surfaced road not subject to enemy, shell fire. (2) Specially constructed horse-drawn wire carts are authorized for brigades and larger units within the cavalry and infantry divisions. The carts are designed for a 2-horse team and are so used within the infantry division. Cavalry units commonly use a 4-horse team. The wire cart embodies features for paying out and reeling up the wire. Each cart has two reels for holding wire with a combined capacity of 5 miles of type W-39 or ap¬ proximately 2 miles of type W-40 wire. It is necessary to trans¬ fer the wire from the issue spools to the cart reels. skinner lug'') One or both reels may be operated at the same time. (3) Field artillery units are equipped with spe¬ cially designed horse or tractor-drawn reels, which are used to lay wire for their fire-control and com¬ mand systems. The bat¬ tery reel (4-horse) carries approximately 1.7 miles of type W-40 wire. The artillery reel (6-horse) carries 3.2 miles of type W-40 ware. This type is used in field artillery battalions, regiments, and brigades. (4) When conditions warrant, escort wagons may be used in the same manner as motor trucks for paying out wire. Here also the wire may be laid by inserting an axle through the wooden tl- 711 Figure 26.—Terminal strip, type TM-84 34 BASIC FIELD MANUAL BRASS KNOB! BLOCK SLOTTED/ BRASS STUD' EBY TYPE BINDING POST COMPOSITION BASE reel or by using a pay-out reel. The escort wagon is not so mobile as the horse-drawn wire cart, but carries more wire and affords an additional means of laying when other facilities are not available. (5) Hand reel carts, shown in Figure 30, are issued within the division. These small carts are pulled by hand or may be towed behind communi¬ cation carts. Each cart carries two steel spools of wire. The spools may be removed from the cart chassis and replaced by filled spools when they become empty. Each spool has a capacity of approximately one-half mile of type W—44 wire. The cart is so designed that it may be taken apart for packing. (6) Pack reels are de¬ signed for the pay out and recovery of wire from a pack animal. They are normally used by cavalry and pack artillery. (7) Breast reels, as shown in Figure 31, may be strapped onto the breast or back of a mounted or dismounted man. The TL-7/2 Figure 27.—Terminal strip, type TM-84-A Figure 28.—Truck adapted to wire laying BASIC FIELD MANUAL 35 wire may be recovered by the use of a crank. The breast reel holds about 600 feet of type W-44 wire. (8) In laying wire by hand, the wire may be paid out by placing the spool of wire on a stationary axle and carrying the wire away from the spool; by carrying the spool on an axle and paying out the wire while walking along the route; or by making up coils of wire into such weights that a man can carry a coil and pay out the wire while walking. c. After the wire has been laid from the wire-laying device it should be removed promptly from the path of the vehicle to protect it from traffic. In this case the wire-laying device is followed by personnel who use wire pikes (wooden poles with hooks on the end) or the hand for moving the wire into its 36 BASIC FIELD MANUAL desired position. Likewise, in the recovery of wire, the reel is preceded by a lineman, who, with the use of a pike or the hand, places the ware back on the road or path of the reel. SO. Pole climbing.— a. Description of equipment .—The line¬ man’s equipment for pole climbing is a pair of climbers, lineman’s belt, and safety strap. Each climber is provided with a top and a bottom strap. The top strap is for the purpose of holding the climber securely against the leg, while the bottom strap secures the climber near the ankle. The top strap is equipped with a leather pad which is placed between the upper end of the shank of the climber and the leg to prevent the climber from chafing the leg. The lineman’s belt is provided with loops for carrying the various lineman’s tools and two rings to which the safety strap is fastened. The safety strap is placed about the pole for safety and ease while working. b. Fitting equipment .—Climbers should be fitted to the leg so that the end of the shank rests about 2 inches below the knee joint. Both straps should fit snugly around the leg. Care should be taken that the buckles do not rest on the shin or the instep. The belt should fit loosely around the body but suffi¬ ciently tight to prevent its falling down over the hips. The safety strap should be fastened to the belt by snapping both ends to the ring on the left-hand side of the belt. (See fig. 32.) The equipment should be carefully inspected before it is put on. BASIC FIELD MANUAL 37 c. Procedure in climbing. —(1) To ascend the pole, take a natural standing position at the foot of the pole, with the toes about 6 inches from the pole. Raise and extend the arms to a horizontal position, grasping the pole with the palms of the hands, at the same time allowing the body to fall backward to the full length of the arms. Raise the right foot about 10 inches from the ground, keeping it about 1 inch from the pole. With a downward thrust, engage the spur of the climber in the face of the pole about 8 inches from the ground. Lift the body by straightening the right leg and plac¬ ing the weight on the spur which is engaged in the pole. Let the left leg hang free and keep the body away from the pole, as shown in Figure 34. From this position raise the left leg and repeat the thrust in the same manner as before. At the same time raise the left hand about 10 inches on the pole, balancing the body with the right hand. Continue to climb in this manner. (2) Use of safety strap .—Climb to the de¬ sired height. Thrust the spur of the right foot into the pole and shift the weight of the body to the right foot. Pass the left leg around the pole in such a manner as to aid the right hand in supporting the body. Keep the right knee about 5 inches away from the side of the pole. Grasping the pole with the right hand, unsnap one end of the safety strap and pass the end around the pole to the right hand. Aid the support of the body with the left hand and with the right hand fasten the loose end of the safety strap to the right ring on the belt, as shown in Figure 37. Clasp the pole with both hands, leg from around the pole and with a downward thrust engage the spur of the climber in the pole on a level with the right foot. The heels when in the proper and most comfortable position should be 3 inches apart. Lean backward gradually, placing the weight of the body on the safety strap, as shown in Figure 38. Adjust the safety strap to its proper position on the pole. Figure 32.—M e t h o d of wearing pole-climb¬ ing equipment Remove the left 38 BASIC FIELD MANUAL (3) To descend the pole, unhook the safety strap, using the above procedure in the reverse order. Climb down the pole, throwing the weight of the body slightly on the right or left leg, alternately, in order to place more force on each downward thrust. 31. Wire lines, definitions and types.—A wire line con¬ sists of one or more wire circuits along the same route. Mili¬ tary wire lines are classified according to their general type of Figure 33. —First position in climbing \ RL-P-SSS? Figure 34. —Second position in climbing construction as cable lines, standard pole lines, semipermanent pole lines, and field wire lines. 32. Surface line construction. —During movement of units in combat, field wire lines are laid hastily on the ground. This type of wire line is termed a surface line. Surface lines must be protected from traffic at command posts, road crossings or other places where traffic lanes cross the line. Surface lines are laid loosely in order that the wire may be flat on the ground and so as to provide sufficient slack for repairing breaks and facilitating subsequent changes in the type of construction. BASIC FIELD MANUAL 39 At suitable intervals, surface lines should be attached to objects such as trees or posts in order to leave sufficient slack, and so as to prevent passing troops and transports from pulling the wire into traffic lanes. The wire is tied to the tree or post at the ground level. When surface lines are routed along a road, the wires must be kept off the traffic lane. If the road curves in one general direction, the line should, if practicable, be routed along the concave side. When surface lines are routed along the convex side of a road, the line must be secured at several Figure 35.—Third position in Figure 36.—First position in climbing using the safety strap points along the curve. Advantage should be taken of objects, such as trees or posts, along a curve in the road to prevent the wires being pulled into the traffic lane. Connections between surface lines and standard pole lines are made preferably at existing terminals of the standard pole line; if such terminals are not conviently located a test station may be established. When surface lines connect with permanent overhead construc¬ tion, the surface line must be securely tied at the base of the pole at which the connection is made and again just above the cross arm or terminal can where the connection is to be made. 40 BASIC FIELD MANUAL If more than one surface circuit is to be connected to a permanent line, a test station should be installed at the junction of the two types of lines. Connections to aerial or buried cables are made only at standard cable terminals. 33. Overhead construction.—Field wire lines are placed overhead by fastening the wire to small knobs attached to trees, buildings, or existing poles at a height of 14 feet above the ground. In case knobs are not available, the wire is fastened to the sup- Figuke 37.—Second position in using the safety strap Figure 38. —Third position in using the safety strap ports by means of standard field ties. This type of construction is employed near command posts, test stations, overhead road crossings, and other points along surface lines where traffic lanes cross the wire. Test stations should be installed at the head of construction and at the junctions of overhead lines with other types of construction. At junctions between overhead and other types of construction the wires are tied securely to the bottom of the support and tagged. 34. Road crossings. — a. Where possible, - field wire lines should cross roads at culverts. The wires are passed through the culvert and tied at the entrance and exit to prevent contact with water. BASIC FIELD MANUAL 41 b. Wires which cross roads overhead must clear the crown of the road by 14 feet. When a surface line crosses a road on poles or other objects, the wires should be tied at the base and top of the object on each side of the road. The strain which occurs along the line is met by the tie at the base. c. If neither of the above methods can be used, the line wires should be buried in a trench, crossing the road at right angles. The wires must be laid snug and secured at both ends of the trench to pre¬ vent their being pulled out. A small amount of slack wire should be left at each side of the road to permit replacement of the portion under the road should it become worn or water soaked. Lines are tied to trees, posts, stakes, or other suitable objects. d. Circuits crossing roads in any of the above methods are tagged at both sides of the road. e. The passage of captive balloons along roads requires that their movements be unhampered by interference from overhead Figure 39. —Method of tying wire at ground level; (a) correct, (b) incorrect Figure 40.—Method of tying wire along curve in road wires. Therefore, when practicable, wires should be routed underneath roads. When overhead construction is necessary provision should be made to permit the wires to be lowered to the road surface. Little or no damage will result to the wires by the occasional passage of balloon vehicles over them. 42 BASIC FIELD MANUAL 35. Railroad crossings.- —Field wire lines should cross rail¬ roads under the rails. If a bridge or culvert is available, the wire should be laid through the bridge or culvert, as described in paragraph 34. 36. River crossings.— a. Overhead .—Small stream crossings are made in the same manner as overhead road crossings, except that the wires need be only high enough to clear traffic. A span of more than 150 feet should not contain a splice. Long spans can be made with Figure 41.—Method of tying wire at junction of gg ld wire but special surface line with overhead construction construction is necessary for resisting the strain. Figure 46 illustrates methods which have been adopted for military telegraph lines in Alaska, where it was necessary to cross swift rivers and mountain gorges. Figure 46 a and 6 shows two methods of providing support for BASIC FIELD MANUAL 43 excessive strain on long spans. The line wire is made fast at G, laid in the saddle at D, pulled up at saddle at C, and made fast at strain insulator attached to H. As much sag as practicable should be allowed, as the strain increases rapidly as the wire is pulled taut. Figure 46 c and d shows method of constructing saddles for supporting long spans. Figure 46 e shows an addi- Figure 44.—Wire crossing under road in trench tional method of terminating a long span wire, the wire having passed over a saddle not shown in the figure. A modification of the above method must be made to fit the material at hand in 44 BASIC FIELD MANUAL each case, but the principles of guying illustrated above should be followed. b. Submerged .—When field wire lines must cross bodies of water, such as rivers, where it is impracticable to make overhead crossings as described above, the wire should be submerged. The wire is tied in securely on the near bank, laid by paying out from reel across the water, and tied in securely on the far bank. When the water level is affected by tidal raises the ties should be above the high-tide level. The insulation on the wire should be sound. If the width is such as to necessitate the splicing of more than one length of wire together, the splicing should be done on the near shore and the entire length of wire made up into a single coil or placed on one reel. Such splices should be wrapped with rubber tape and then with friction tape. When the width is one-half mile or less a reel cart, type RL-16, may be placed in a pontoon or small skiff and the wire payed out from the reel while the boat is rowed across the water. When the current in the water is such as to wash the wire in the direction of the current, weights should be placed on the wire at suitable intervals during the laying to insure the wire will submerge to the full depth. The current of moving water should be considered and the effect of the current on the path of the boat computed to determine the approximate length of wire required for the cross¬ ing so that it may be prepared prior to the crossing. Splicing in midstream is impracticable. BASIC FIELD MANUAL 45 37. Construction at circuit terminals. —The following procedure should be followed as far as practicable in the laying of field wire away from a terminal and approaching a terminal: a . At the starting point, the free end of the wire is tagged to show the circuit designation, as in Figure 25. This tag is placed about 1 foot from the end of the wire. b. Leaving sufficient wire at the free end to reach the terminal frame or other fixed installation, the wire is tied in to some object. c. The free end of the wire is connected to the binding posts on the terminal frame or instrument. If a terminal frame is to be Figure 46.—Construction of terminals for stream crossings installed later, the wire is connected to a telephone or other instrument, which may be used in making tests on the circuit until the frame is installed. d. The chief of construction directs the laying of the wire. He follows the general route prescribed by the signal unit commander. e. The wire is laid to the designated point. It is tagged and tied in and a free end left with sufficient slack to run to the oper¬ ating installation (terminal frame or instrument). The circuit is then tested. When the circuit is found to be in order, it is turned over to the operating detail, who connect it to the ter¬ minal frame or instrument. After the circuit is connected, the chief of construction calls back over this completed circuit to 46 BASIC FIELD MANUAL the starting point or wire chief, reporting the installation and receiving confirmation as to its operating condition. If the circuit has been connected to a switchboard or a terminal frame through which it is connected to a switchboard, he places his call through the switchboard. If connected to a local instru¬ ment, the call is made from this instrument. Thus, any fault in the terminal connection is detected and corrected before the chief of construction makes his report over the circuit. If the operating detail has not arrived at the terminal, the chief of construction will leave a member of his detail at the end of the wire. This man is equipped with a telephone or suitable test instrument which he connects to the circuit. He remains to turn the circuit over to the operating detail on their arrival and to test back over the circuit after it is connected, or awaits competent orders directing otherwise. /. The chief of construction makes any additional notes neces¬ sary on his line route map and circuit diagram to complete the record of the circuit. He turns this information over to his im¬ mediate superior at the first opportunity. 38. Test station construction. — a. Test stations are in¬ stalled in a field wire system to facilitate testing and cross connecting circuits within the adjoining sections. For identifica¬ tion, a test station is given a name derived from its geographical location, for example, Knob Hill Test. Test stations are located at points along wire lines where it is considered desirable to adapt the construction of the line for ready testing, or at points where command posts have been, or are likely to be, located. b. Test stations are constructed when the wire lines are ini¬ tially laid or are cut in on the lines later, and are cut out when their use is no longer advantageous. The site selected for the location of the test station should afford cover from hostile ob¬ servation and fire and protection from friendly troop move¬ ments and should be accessible for testing. A test station con¬ sists of one or more terminal strips. The circuits are connected to pairs of binding posts on the right-hand side of the terminal strip. Circuits are cut through the test station by jumpering the corresponding binding posts on the left-hand side of the terminal strip. The jumpers for this purpose are pieces of flexible insu¬ lated wire. The terminal strips are fastened to a support such as a tree or fence post. The wire circuits are tagged and tied in before being connected to the terminal binding posts. BASIC FIELD MANUAL 47 (1) Construction of test station during initial installation of wire lines .—Locate the site of the test station. Lay wires to this location. Tag and tie in circuits near the terminal-strip posi¬ tion. Secure the terminal strip or strips to a support. The number of strips used depends upon the number of circuits en¬ tering and leaving the test station, as there must be a pair of binding posts for each circuit. Connect the lowest numbered circuit entering the test station to the top right-hand pair of binding posts on the terminal strip. Connect the next lower numbered circuit to the next lower pair of binding posts and continue in this manner until all are connected. The wires ex¬ tending forward from the test station are laid, being tied in near the terminal strip. The lowest numbered of these circuits is con¬ nected to the pair of binding posts at the top of the lower half of the terminal strip, and so on until all are connected. When an even number of ter¬ minal strips is used, the /^Trunks - number of pairs of bind¬ ing posts wdll be even and can be evenly divided into an upper and lower half. If the number is odd, the num¬ ber of pairs of binding posts will be odd. In this case, leave the odd pair between the upper and lower halves. Take jumpers, prepared from lengths of flexible insu¬ lated wire, which are suf¬ ficiently long to reach from the top binding post to the lowest binding post on the terminal. Connect the proper circuits to¬ gether. The installation is shown in Figure 47. A telephone or other suitable instrument is connected to the designated test cir¬ cuit as prescribed in paragraph 75. (2) Construction of test station after initial installation of wire lines .—Locate site of the test station along the route of the line. Secure the terminal strips to a support. Take the lowest numbered circuit and pull in slack on the wire. Tie in the wire near the terminal strip. At a point where the wire reaches the terminal, strip off about 2 inches of insulation from one wire and attach it to the top right-hand binding post. Remove the PL-P-550G Figure 47 Twisted Pair Fie/d Wire or Outpost Wire - -Test station constructed during initial installation of wire lines 48 BASIC FIELD MANUAL same amount of insulation from the other wire and connect it to the lower binding post of the pair, as shown in Figure 48. Measure off a sufficient length of wire to reach to the binding posts of the pair from which the circuit is to leave the terminal, and by removing the insulation as before, connect the wires to these binding posts in the same order. Tie in the wires near the strip. Jumpers are now connected to the corresponding binding posts on the left-hand side of the terminal strip. The loop in the circuit wire between the upper and lower pair of binding posts is cut away, cutting the wire close to the binding posts. Other circuits are cut in to the test station terminal strip Figure 48.—Method of connecting wires to terminal strip in construction of test station after initial installation in a like manner. Beginning at the top with the lowest num¬ bered circuit, circuits will be cut in in numerical order. c. Removal of a test station .—When a test station is to be abandoned, it is the usual practice to leave the terminal strip connected. It may happen that, due to shortage of terminal strips, it is necessary to remove the terminal strip and splice the circuits through. Before removing any circuit from the strip, the lineman on duty at the test station first listens in on it and satisfies himself that it is not in use. He then calls on the circuit and notifies the switchboard operator that the test station is to be removed and the circuits cut through. Then, taking two wires that are connected together by the same jumper, he BASIC FIELD MANUAL 49 removes them from the binding posts and splices them together. The other wires of the pair are then spliced in a like manner. Other circuits are removed from the strip and spliced similarly. 39. Routing field wire lines.— a. The signal officer pre¬ scribes the general route to be followed. The chief of construc¬ tion is usually allowed considerable latitude in the selection of the actual route. b. Maintenance is facilitated by using the minimum number of routes. The route should be adapted to the means available for laying the wire. It should be so located that the line can probably be used by the same or another friendly unit after the movement of command posts. It should afford cover from hostile observation and fire. Main traffic routes, shelled areas, and the areas over which tanks or tractors are likely to pass should be avoided wherever practicable. 40. Construction orders.— a. The chief of construction should receive orders prescribing the number of circuits to be installed, the priority of installation, and the action to be taken on completion of the installation. He should receive the following descriptive information relative to each circuit to be laid: (1) Numerical designation. (2) The route. (3) Whether a trunk or local circuit. (4) Whether a metallic or ground return circuit. (5) Type of wire. (6) The centrals and test stations which it will connect or pass through, including code names and organizations served. (7) Approximate length. (8) Type of construction. (9) Nature of roads and terrain. (10) Precautions to avoid damage from friendly troops and materiel. (11) Tests and reports required. b. This information is imparted by the use of a line route map and circuit diagram, supplemented by oral or written instruc¬ tions from the signal unit commander. 41. Procedure in laying field wire. — a. The wire for the circuits is tested before starting to insure the continuity of each spool. Spools of wire which when tested do not show a con¬ tinuous circuit are not used until the trouble is corrected. b. The terminal connection is made as prescribed in para¬ graph 37. The detail then moves out and the chief of con- 50 BASIC FIELD MANUAL struction directs the laying of the wire over the detailed route. When necessary, he causes the wire to be placed to the side of the path of the wire-laying vehicle, so as to give the required protection to the wire. He determines the type of construc¬ tion to be used if not already prescribed in his orders, as well as any changes in the type of construction, directing when and where they are to be made. He causes a test to be made back Figube 49.—Wire trench construction to the starting point before and after making a splice in the wire being laid, in order to insure the continuity of the splice. When connections are made at terminal strips, he causes the circuit to be tested from the far side of the connection back to the starting point. Should the wire be laid to any location where a central is to be installed but where the equipment for the installation has not arrived, the chief of construction leaves BASIC FIELD MANUAL 51 a man at this point to inform the arriving personnel of the lo¬ cation of the circuit and to assist in making the terminal con-' nections. Sufficient slack is left at these places to permit running of the circuit to the probable location of the central. c. The wire having been laid to the designated installation, the terminal connections are made and the circuit tested and reported, as prescribed in paragraph 37. 42. Trench, line construction. — a. In zone defense, field wire lines are often installed in trenches. In general, two kinds of trenches are used: (1) Wire trenches constructed for this purpose, and (2) Trenches that are constructed primarily for other pur¬ poses, such as fire and approach trenches. b. (1) Wire trenches vary in size from 10 inches wide by 10 inches deep to 36 inches wide by 30 inches deep. They afford considerable protection from shell fire but offer an obstacle to friendly traffic. The wire may be fastened to cross arms which are attached horizontally to short poles or rest against or pro¬ ject into the sides of the trench. Instead of using cross arms, the wire may be fastened to the sides of vertical poles. Twisted pair may be tied directly to these supports with wire or string, but it is preferable to tie the wire to wooden or porcelain knobs or insulators. (2) The wire trench route should be chosen with a view to concealment, cover, and ease of construction. The wire is kept in the main trunk-line trenches as much as practicable. Switching centrals may be installed at important trench junc¬ tions. (3) In digging the trench, the workers are divided into groups of two men each, each group equipped with a pick and shovel. Two men can dig from fifteen to thirty-five lineal yards of trench per day in good ground, depending on the type of trench. (4) Trench posts are set in the ground at intervals of fifteen to twenty-five feet. They are guyed at turns and at the ends of the line. When fastening wire to vertical poles, insulators may be nailed on opposite sides of each pole. As many as 14 twisted pairs can be carried on a single pole line of this type in a trench about thirty inches deep. A liberal allowance of wire should be made for sag. (5) Trench lines may be terminated by running directly into a telephone central or test station or connecting to some other type of construction. 52 BASIC FIELD MANUAL (6) When necessary to cross a road with a wire trench, the line should preferably be placed in a buried conduit of wood, clay, or iron. If this is impracticable, the wires should be carried overhead on poles. c. (1) When it is impracticable to construct wire trenches, field wire may be installed in fire or approach trenches. This will be normal within the intrenched area of the infantry regi¬ ment. Owing to the great use made of these trenches by combat troops, they are not satisfactory except for temporary wire installations. (2) Except in narrow fire trenches, wire lines should be kept ordinarily on the side of the trench nearest the enemy. Wire placed at heights between 10 and 30 inches from the duck boards or bottom of the trench is least subject to damage from cave-ins, water, and traffic. (3) Field wire may be fastened to the side of a trench, as shown in the composite Figure 50, by— (a) Staples made of stiff wire and about 12 inches long. The staples are driven into the ground as far as possible, thus holding the wire closely against the side of the trench. (b) Attaching the wire to insulators mounted on boards which are fastened to the sides of the trench by rods or staples. BASIC FIELD MANUAL 53 (c) Attaching the wire to insulators nailed to the ends of wooden stakes or pegs which are driven into the trench wall. (d) Attaching the wire to insulators nailed to posts which are driven into the bottom of the trench close to the side. (e) Passing the wire through supports made of No. 9 or heavier GI wire. One end of the support wire is attached to a stake driven into the ground just outside the edge of the trench. (/) Attaching the wire to revetment posts, either directly or on insulators. d. Trench wire lines are tagged at intervals of not more than 150 feet or at junctions with other lines. Section III INSTALLATION AND OPERATION OF TELEPHONES AND CENTRALS 43. General. —This section furnishes information for both the operating and using personnel. It prescribes in detail the training needed for the operating personnel with a few cautionary references of value for the using personnel and message centers. 44. Telephone centrals.— a. A telephone central is es¬ tablished at each echelon at a headquarters where two or more local telephones are installed and at junctions of wire lines where interconnecting is desired. b. The telephone central serves the following purposes: (1) To provide flexible intercommunication between local telephones and to afford connection to circuits leading to other units. (2) To serve as a switching central at a junction of wire lines, thereby reducing the number of circuits required and adding flexibility to the system. (3) To furnish a place at which all circuits are accessible for test and from which maintenance may be directed. 45. Telephone conversations. — a. Telephone conversations should be brief, as long conversations deprive others of the use of the circuits. This can best be accomplished by mentally pre¬ paring the subject matter of telephone conversations before the call is made. The telephone should not be used for long re¬ ports, orders, or messages when messenger or telegraph would 54 BASIC FIELD MANUAL serve as well or better. Telephone conversations must be discreet, since secrecy is never assured. Telephone conver¬ sations may be intercepted by direct tapping of the line, by induction from our own lines, and by leaks to the ground and thence to enemy listening sets. b. No unnecessary conversation should be held with the switchboard operator. In case it is desired to make a com¬ plaint regarding the service ask for the chief operator or com¬ munication officer. The operator should not be directed how to route a call. The switchboard operator should be spoken to in a civil manner. 46. Use of telephone code names. — a. To simplify and expedite the operation of a telephone system, and to conceal the identity of tactical organizations, code names are assigned to tactical units. These code names are prepared by division signal officers for use throughout the division. In corps and armies the signal officer prepares code names for the unit head¬ quarters and for corps and arnw troops. A telephone central takes the code name of its tactical unit. b. The manner in which code names may be assigned is illus¬ trated in the following partial list for the 1st Division. These coded names are given as examples only. They do not remain fixed, but are changed from time to time. Unit Code name Headquarters, 1st Division_ Danger. 1st Signal Company_ Daylight. 1st Field Artillery Brigade_ Denver. 1st Field Artillery_ Dollar. 1st Battalion_ Dollar Red. 2d Battalion__ Dollar White. 1st Brigade_ Dig. 1st Infantry_ Deer. 1st Battalion_ Deer Red. 2d Battalion_ Deer White 3d Battalion_ Deer Blue. 47. Designations for officers and offices. — a. Enlarging upon this system of unit code names, officers, and offices at a BASIC FIELD MANUAL 55 headquarters are given code designations for use in telephone conversations. The complete designation consists of the unit code name and a distinguishing number. b. The following list shows the assignment of code-number designations to officers and offices at a headquarters. This assignment remains fixed. Title Code number Commanding officer orC. G_ 6 Adjutant (not G-l)_ 7 . Chief of staff or executive officer_ 5 S or G-l or administrative officer_ 1 S or G-2 or intelligence officer_ 2 S or G-3 or operations officer, or plans and training officer. _ 3 S or G-4 or supply officer_ 4 Ordnance officer_:_ 8 Inspector- 9 Signal or communication officer_ 10 Message center_ 11 Machine-gun officer or machine-gun and howitzer officer_ 12 Aide-de-camp_ 13 Air officer_ 14 Engineer officer_ 15 Surgeon or medical officer_ 16 Judge advocate_ 17 Finance officer_ 18 Chaplain_ 19 Postal officer_ 20 Quartermaster (not supply officer)_ 21 Chief of artillery or artillery officer_ 22 Gas officer_ 23 Liaison officer_ 24 Munitions officer_ 25 Pigeon loft_ 26 Provost marshal, commanding officer special troops or headquarters commandant_ 27 Radio station_ 28 Reconnaissance officer_ 29 Telegraph office_:_ 30 Telephone wire chief or trouble chief_ 31 Veterinarian_ 32 Public telephone_ 33 56 BASIC FIELD MANUAL c. In placing a telephone call, the code name of the organiza¬ tion and the designating number of the office or individual are used rather than the organization name and individual’s title. For example, in calling the executive officer of the 1st Brigade, call for “Dig five,” and to call the commanding officer, 1st Battalion 1st Infantry, call for “Deer Red six.” Code name and number lists should be posted at each telephone instrument. 48. Use of phonetic alphabet.—Certain letters of the alphabet have similar sounds and are often confused in telephone conversation. To avoid this difficulty, the following pronuncia¬ tion of letters over the telephone should be used habitually. Words that are liable to be misunderstood will always be spelled out. For example, in transmitting the plain text words BARTS CHURCH the word BARTS is apt to be misunderstood. Its phonetic spelling would be as follows: BOUGH-ACK-R-TOC- ESSES. The phonetic alphabet has its especial value in the transmission of telephone or cryptograph messages in which groups are almost entirely unpronounceable; for example, the code group XISV would be spelled X-I-ESSES-VIC. Do not use the expres¬ sion “A as in ACK.” A pronounced ACK. B pronounced BOUGH. C pronounced CAW. D pronounced DON. E pronounced E. F pronounced F. G pronounced GOGO. H pronounced H. I pronounced I. J pronounced JIG. K pronounced K. L pronounced L. M pronounced EMMA. N pronounced N. O pronounced O. P pronounced PIP. Q pronounced QUASH. R pronounced R. S pronounced ESSES. T pronounced TOC. U pronounced U. V pronounced VIC. W pronounced W. X pronounced X. Y pronounced YOKE. Z pronounced ZED. This list is posted on each telephone instrument for the con¬ venience of the using personnel. 49. Pronunciation of numerals.— a. The following pro¬ nunciation of numerals is used habitually in telephone conver¬ sation : BASIC FIELD MANUAL ,57 Nu¬ meral Pronounced Principal sotmds 0 Ze-ro__ - Long O. 1 Wun_ _ Strong W and N. 2 Too..-- Strong T and long OO. 3 Th-r-ce.-- - .. Slightly rolling R and long EE. 4 Fo-wer_.. Long O, strong W and final R. 5 Fi-iv_ I changing from long to short and long V. 6 Siks_ Strong S and KS. 7 Sev-ven. Strong S and V, and well-sounded EN. 8 Ate Long A and strong T. 9 Ni-yen . . Strong N, long I, and well-sounded YEN. This list is posted on each telephone instrument for the con¬ venience of the using personnel. b. When transmitting numbers, each numeral will be pro¬ nounced separately except in the case of even hundreds, thou¬ sands, or millions, when the word “hundred,” “thousand,” or “million” will be used. For example: 44 is pronounced Fo-wer fo-wer. 80 is pronounced Ate ze-ro. 136 is pronounced Wun th-r-ee siks. 500 is pronounced Fi-iv-hun-dred. 1478 is pronounced Wun fo-wer sev-ven ate. 7000 is pronounced Sev-ven thou-sand. 12084 is pronounced Wun too ze-ro ate fo-wer. 16000 is pronounced Wun siks thou-sand. c. When calling a number, speak the name of the central deliberately and distinctly, pausing between the name and the first digit. Speak each digit separately, pausing slightly between digits. In the following examples a short dash represents a pause of about one second, and a long dash indicates a slight pause. Table 44; “Ta-ble - Four—Four.” Turkey 80, “Tur-key - Eight—Zero.” Track 6100, “Track - Six—one—hundred.” 50. Preparing cable for monocord switchboards. —Each monocord and camp switchboard is equipped with a switch¬ board cable and terminal strip as a part of a central installation prior to its use in the field. Once the cable and strip are con¬ nected to the switchboard they remain an integral part of it and should not be disconnected except for replacement. Cable for the monocord switchboard may be improvised in the following manner: 58 BASIC FIELD MANUAL a. Take any type of twisted pair wire (outpost twisted pair is suitable, as it is flexible and light) and cut it into 11-foot lengths, cutting one more length than there are units on the switchboard. b. Stand facing the switchboard, connect one pair of wires to the left-hand line circuit terminals of the switchboard and temporarily attach the other end of the pair to the upper left-hand pair of binding posts on a terminal strip, placed about 8 feet from the switchboard. To connect to the switchboard line circuit terminals, skin off only enough insulation from the end of each wire, so that when the wire is fully inserted in the binding post the insulation will touch the binding post. Similarly con¬ nect the other circuits in order from left to right on the switch¬ board and from top to bottom on the terminal strip. Leave the unused pair sufficiently long so that each free end will reach to any pair of binding posts; this is a spare pair for use in case one of the others becomes unserviceable. Figure 51.—The lock stitch c. Take a piece of lacing twine or other stout cord and, begin¬ ning at the switchboard, lace the wires together neatly and se¬ curely, using a lock stitch, as shown in Figure 51. Each pair of wires should leave the cable together as a pair (see fig. 52) rather than as individual wires. Work toward the terminal strip in lacing, spacing the stitches about l}i inches apart and pushing the slack in the wires ahead of the lacing so as to make a neat and compact cable. At the terminal strip the wires of each pair should come out as a pair, opposite the desired left-hand binding posts on the terminal strips. Cut the wires so that each will be of the proper length for attaching to its proper binding post and then attach them in the same order as before. Leave the ends of the spare pair free until the cable is completed, then lace them down with a separate piece of twine so that when needed it will not be necessary to cut the main lacing of the cable. d. Secure the cable to the switchboard to relieve the binding post connections of all strain. Route the cable down the left or right hand side of the switchboard. The arrangement as shown in the figures is for illustrative purposes only. Equipment should be so arranged that it can be most effectively operated under BASIC FIELD MANUAL 59 existing conditions. Secure cable to wooden back by clamping it, with strips of leather held down with brass screws. Terminal strips may be mounted on a wood strip and cable secured to wood to relieve the terminal strip binding post connections of strain. Cable is coiled during transportation to prevent injury. 51. Installation of terminal frames. — a. Terminal strips are installed to provide terminal connections for line circuits. Where line circuits terminate in a terminal strip it is known as a line terminal strip. Where a switchboard cable terminates in a terminal strip it is known as a switchboard terminal strip. The two together constitute the terminal frame. The terminal frame should be located near the switchboard and to the rear or to one side, either right or left, so that the switchboard operator will not be disturbed by personnel working at the frame. When 1143°—31 3 60 BASIC FIELD MANUAL two sets of terminal strips are used as a line terminal strip and a switchboard terminal strip, they are placed about 8 to 12 inches apart and the corresponding circuits are connected by jumpers. Figure 53.—Terminal frame installation Circuits connected by jumpers are spoken of as jumpered. Sets of terminal strips to be used as line and switchboard terminals are not made up as a unit for central installation. The procedure BASIC FIELD MANUAL 61 of converting a test station into a central or cutting out a central and leaving a test station is built on the principle that the line terminal strips are an integral part of the line and not a part of the central equipment. When it is desired to mount the terminal strips on boards for convenience in installation, the switchboard terminal strips are mounted on one board and the line terminal strips on another board. b. To connect field or outpost wire to the binding posts: (1) On type TM-8/ h terminal strips .—Skin off 3 inches of in¬ sulation from the end of the wire to be connected. Pass the wire through the skinner lug and around the binding post under the washer, going in the direction the wing nut is turned in tightening, and again through the skinner lug. Tighten the Figure 54.—Wire connected to terminal strips; (a) type TM-84-A and (6) type TM-84 wing nut. Cut off the projecting loose end and about one-eighth of an inch beyond the skinner lug without leaving loose strands projecting that might touch adjacent connections. (2) On type TM-84—A } terminal strip .—Skin off about three- quarters of an inch of insulation from the end of the wire to be connected to the binding post. Open the slot in the post to the full extent. Insert the wire end into the slot so that it projects through the post. Firmly tighten the knob clamping the wire with the fingers. Do not use pliers to tighten these binding posts, as their threads may become stripped. c. Jumpers are prepared from flexible insulated wire of suffi¬ cient length to permit their being connected between the top and bottom binding posts on the strips. The ends may be con¬ nected in the same manner as stated in b above, or may be fitted 62 BASIC FIELD MANUAL with either lugs or clips for rapidity in making connections to the type TM-84 strip. 52. Repeating coils— use and installation.— a. Repeating coils now issued are of commercial design. The ends of the coils are brought out to terminals numbered 1 to 8 as shown in Figure 55. b. Repeating coils are used in field wire systems for the construction of sim¬ plex and phantom circuits. Additional telephone or tele¬ graph channels may be se¬ cured by the use of these coils. • (1) A simplex circuit is a ground-return circuit super¬ imposed on a metallic cir¬ cuit. The simplex circuit may be used for telephone or telegraph. This permits the simultaneous use of the simplex circuit for telephone or telegraph and the metallic circuit for telephone, without mutual interference. (2) A phantom circuit is a metallic circuit constructed from two physical metallic circuits. This installation permits the simultaneous use of the phantom circuit for telephone or tele- Figure 56.—Simplex circuit constructed with repeating coils graph and the two physical metallic circuits for telephone, without mutual interference. The two physical circuits are known as side circuits. The third metallic circuit is known as a 'phantom circuit. The combination of the three circuits is known as a phantom group. BASIC FIELD MANUAL 63 c. The simplex circuit .■—A simplex circuit is constructed by placing a repeating coil at each end of a metallic circuit as shown in Figure 56. Nos. 1 to 8 refer to terminals as marked on the repeating coil shown in Figure 55. Nos. 9 and 10 are the ter¬ minals of the telephone circuit which may be connected to a switchboard, local telephone, or another telephone line. Nos. 11 and 12 are the terminals of the simplex circuit which may be connected to a switchboard, local telephone, or another telephone line for use as a telephone line or which may be connected to telegraph instruments for use as a telegraph line. The connec¬ tion to the mid-point of the line side of the repeating coil is some¬ times termed the telegraph leg or Morse leg. d. The phantom circuit. —A phantom circuit is constructed by placing a repeating coil at both ends of each of two physical 3 2 A LINE A 2 S Figure 57.—Phantom circuit constructed with repeating coils circuits and connecting the center points of the line sides of the Wo repeating coils at each end of the side circuits as shown in Figure 57. Nos. 1 to 8 refer to the terminals on the four repeat¬ ing coils, as marked on the repeating coil shown in Figure 55. Nos. 9 and 10 are the terminals of the two side circuits. Nos. 11 and 12 are the terminals of the phantom circuits. The terminals of the side and phantom circuits may be connected to a switchboard, telephone, or another telephone line. Telegraph instruments may be connected to the terminals of the phantom circuit if a metallic telegraph circuit is desired. e. Effect of repeating coils on transmission range. —-The intro¬ duction of a repeating coil reduces slightly the efficiency of the 64 BASIC FIELD MANUAL metallic circuit to which the coil is connected. Simplex circuits and phantom circuits are more efficient than the physical or side circuits upon which they are superimposed. /. Mutual interference .—In the above types of construction mutual interference results only when each wire in the simplex or phantom group does not have the same impedance. It is important that the repeating coil be connected as shown, as the half of the repeating coil connected to the line is more carefully constructed than that intended for connection to the local instrument or switchboard. If the two halves of the complete electrical path between terminals 3-8 on one coil and terminals 3-8 on the coil at the far end of the circuit are not exactly of the Figure 58.—Resistance (R) connected to balance simplex circuit same impedance the circuit is said to be unbalanced, and inter¬ ference between simultaneous signals passing over the side circuit and phantom circuit on the physical circuit and the simplex circuit will occur. It is impossible to obtain a perfect balance in a field wire system, but the mutual interference may be reduced to a negligible value. Poor splices are the primary cause of unbalance in field wire lines. A variable resistance may be inserted in the low resistance side of an unbalanced field line to improve the balance. The low resistance side is deter¬ mined by trial first with the resistance in one side and then in the other. After determining the low resistance side the resist¬ ance is varied until the line is balanced or the interference is reduced to a minimum. Figure 58 shows the method of connecting the variable resist¬ ance unit in an unbalanced simplexed line. Nos. 1 to 8 refer to the numbers on the tw r o repeating coil terminals. Li and L 2 are the two wires of a twisted pair. L 2 is slightly defective. The variable resistance R is inserted in Li between the repeating coil BASIC FIELD MANUAL 65 terminal and the terminal of the wire at one end of the circuit and is varied until an approximate balance is obtained. g. Installation of repeating coils. —(1) Prior to being taken into the field, repeating coils of commercial types should be prepared for field installation as shown in Figure 59. Terminals 1 and 6 and 3 and 8 are’ connected together. Terminals 4 and 7 are connected to binding posts marked Li and L 2 . Terminals 2 and 5 are connected to binding posts marked Tpi and Tp 2 . Terminals 3 and 8 are connected to a binding post marked Tg. All connec¬ tions must be soldered and all wires must be protected from mechanical injury. The binding posts are screwed to a thin piece of wood on which the repeating coil is mounted. (2) Repeating coils installed at a switchboard are mounted between the line and switchboard terminal strips either above or below. (See fig. 60.) (3) Repeating coils installed at a test station are mounted to the left of the terminal strip. (4) Repeating coils must be protected from moisture. 53. Installation of monocord switchboard. — a. The monocord switchboard with cable and switch¬ board terminal strip attached is Installed in the following manner: Figure 59.—Repeating coil adapted for field use (1) Secure the switchboard to a support. Holes in the wooden back permit the tying of the switchboard to a support with a piece of wire or stout cord. Unit and operator’s cords should hang free without allowing the plugs to touch the ground. The switchboard should be vertical or tilt slightly forward to permit the drops to fall when released. (2) Complete the terminal frame by installing the switchboard terminal strip between 8 and 12 inches to the left-hand side of the line terminal strip. Route the cable from the switchboard to the terminal strip so as to afford maximum protection against injury. 66 BASIC FIELD MANUAL (3) Jumper circuits from line terminal strip to appropriate binding posts on switchboard terminal strip. (4) Connect the operator’s telephone to the switchboard terminals marked Li and L 2 . Connect the ground rod to the terminal marked G. Connect the night bell to the terminals A and Aj and the bell battery to terminals B and Bi. Move the shutter locks of the units to be connected to line circuits to a horizontal position. Write with a lead pencil (not ink or in¬ delible pencil) the de¬ signation of the cir¬ cuits on the small white celluloid strips on each switchboard unit. (5) Test the instal¬ lation to insure satis¬ factory operative con¬ dition. Tests appli¬ cable are described in paragraph 74. b. Caution. — The arrangement of the equipment as shown in the illustrations is not mandatory but for illustrative pur¬ poses o n ly . The equipment should be so arranged as to per¬ mit the most effective operation of the installation under the existing conditions. 54. Installation of monocord switchboards in parallel.— a. Circumstances may arise where one monocord switchboard is insufficient for the number of circuits. In this case two or more monocord switchboards may be connected in parallel. Usually only two will be necessary, as organizations requiring more will be equipped with switchboards of a type having a greater num¬ ber of drops. The number capable of being installed in parallel, except as in b below, is limited by the length of the cords, wffiich must be sufficiently long to reach any jack in the group. In¬ stallation is made as follows: SW ITCH B OAR 0 TERMINAL STRIP LINE TERMINAL STRIP TL-666 Figure 60. -Repeating coil mounted at terminal frame BASIC FIELD MANUAL 67 (1) Install first monocord switchboard as prescribed in para¬ graph 53, leaving sufficient space between the switchboard and operator’s telephone to place the desired number of additional switchboards. (2) Install additional monocord switchboards to the right- hand side of the first. Installation is the same, except that only Figure 61.—Installation of monocord switchboard certain terminals are connected and these are connected in parallel to the corresponding terminals on the first switchboard as shown in Figure 62; to ground the switchboard, connect terminals G to G; to make use of the night alarm, connect ter¬ minals Ai to Ai and Bi to Bi; when the operator’s cord on the first switchboard is not sufficiently long to reach all units on the additional switchboards connect terminals Li to Li and L 2 to L 2 . 68 BASIC FIELD MANUAL 6. When the monocord switchboards connected in parallel are installed in a manner which prohibits the plugging in of any unit cord in all of the other unit jacks, full use may be made of the switchboards by trunking the switchboards together. This is accomplished by reserving for trunking one or more units on the right-hand side of the left-hand switchboard and a like number of units on the left-hand side of the right-hand switch¬ board. Plug the cord of the. unit of the left-hand switchboard into the jack of the unit of the right-hand switchboard and leave this connection up throughout the operation of the switchboards in parallel. Any connection to be made between the switch- Figuke 62. —Two monocord switchboards in parallel boards where the unit cords will not reach may be made through these two units which are trunked together. 55. Installation of telephone centrals.— a. Installation of a telephone central includes installing the switchboard with operator’s telephone and auxiliary equipment, connecting line circuits through to the switchboard terminal strips, installing testing equipment, installing local circuits, and connecting instru¬ ments thereto, testing the installation to insure its proper functioning, preparing and posting a traffic diagram and tele¬ phone code, and making a # record of the installation. These several operations are described below: (1) Select a convenient site for the location of the telephone central affording as much shelter as possible. BASIC FIELD MANUAL 69 (2) Install the switchboard with its auxiliary equipment and line terminal strips as prescribed in paragraphs 53 and 54. Connect the line circuits to the line terminal strip and jumper to the switchboard terminal strip. If a line terminal strip is not to be used, connect the line circuits direct to the switch¬ board terminal strip. If the switchboard is to be used without Figure 63.—Telephone central using double terminal strips a cable and switchboard terminal strip, connect the line circuits direct to the switchboard unit terminals. (3) Short local circuits are installed by the operating details in the manner prescribed in paragraph 37. These details install the local telephones and maintain the local circuits. When cir¬ cuits which have been laid by the construction details are turned over, the chief of the operating detail has them connected to the proper pairs of binding posts on the line terminal strips. (4) Install the testing equipment as prescribed in paragraph 73 . (5) Test each circuit and when in satisfactory operative con¬ dition report the fact to the chief operator, record the time the 70 BASIC FIELD MANUAL circuit is connected, and inform the message center of the available service. (6) After the central is installed and the circuits are working, rearrange the equipment to improve the appearance of the layout and to facilitate maintenance. Prepare a traffic diagram and telephone code and place them in a convenient location for the operator. b. Care must be exercised that the circuits radiating from a telephone central are not an obstacle to troops and traffic at the headquarters. They should be buried or placed overhead. c. The use of circuits should not be delayed pending the in¬ stallation of the telephone central. If trunk circuits are avail¬ able before they can be connected to the switchboard, they should be connected directly to telephones to give temporary service pending the installation of the switchboard. d. Priority in which telephones are installed at a headquarters varies with the situation and the orders of the commander. (1) At a command post, telephones are normally installed in the following order of priority: Message center. Commander and C. of S. or Ex. Signal service. Operations and training section. Intelligence section. Personnel section. A general utility telephone for personnel not furnished in¬ dividual telephones. Other staff officers and activities as required. (2) At small headquarters, as in battalions and regiments, one telephone ordinarily serves two or more staff officers. At larger headquarters, more than one telephone may be required in each staff section. (3) At rear echelons telephones are reduced to minimum requirements. All routine administration is handled personally or by messenger so far as practicable, leaving the telephone system free for urgent messages. Telephones are normally installed in the following order of priority: Message center. G—4 representative. Ordnance or munitions officer. Quartermaster. Adjutant. BASIC FIELD MANUAL 71 A general utility telephone for personnel not furnished in¬ dividual telephones. Other staff sections and activities as required. 56. Installation of switching centrals.—Switching cen¬ trals are installed in the same manner as telephone centrals. Figure 64.—First step in converting test station into a central Only trunk circuits are normally handled at a switching central. 57. Converting a test station into a telephone central.— The switchboard is set up so as to allow the switchboard terminal strip to be installed to the immediate left of the test station terminal strip. Take four jumpers, preferably one having test 72 BASIC FIELD MANUAL clips fitted to the ends. Temporarily jumper each circuit, one at a time, from the right-hand side of test station terminal strip to the left-hand side of the switchboard terminal strip. At the switchboard, plug through the two units to which the 2-line circuits are to be connected, so as not to interrupt any possible Figure 65. —Second step in converting test station into a central conversation over the circuits during the installation of the central. With the temporary jumpers still on, remove the jumpers on the left-hand side of the test station terminal strip that connect this circuit through the test station. Cross connect the circuit between the two terminal strips. Remove the tem- BASIC FIELD MANUAL 73 porary jumpers. Repeat this procedure on the remaining circuits. Listen in on each circuit entering the switchboard and if a circuit is not busy remove its plug, thus clearing the through connection. Call on each circuit and inform the answering operator that the test station has been converted into a central, giving the code name and any special information applicable. This procedure is reversed when a central is to be converted into a test station. 58. Installation of field telephones. —To connect a field telephone to a metallic circuit, connect the two wires to the 74 BASIC FIELD MANUAL 2-line terminals of the telephone. When connection is made to a ground return circuit, connect one line terminal to the line wire and the other to a ground rod. Place the telephone in a position convenient for the user. Tie in the circuit near the instrument, leaving sufficient slack between the tie and the instrument to permit some movement of the telephone. If the circuit enters the place of installation (building, dugout, or tent) from an over¬ head line, provide a drip loop to drain the water away from the telephone. The telephone code name and office number are marked on a tag fastened to the telephone; this is for the con¬ venience of the user, who is notified as soon as the telephone has been tested and found ready for use. A copy of the telephone code should be with each telephone for the information and use of the user. 59. Shelter for equipment.—Whire operating equipment should be provided with shelter during inclement weather. Ex¬ cessive moisture will affect the operation of telephones, telegraph instruments, test sets, switchboards, terminal strip connections and repeating coils. This shelter must frequently be improvised. Improvised shelter may be secured by using paulins, shelter halves, tent flys, or lean-to structures built from foliage, metal, or wood, the design of which must be left to the ingenuity of the detail. Terminal strips can be mounted in weatherproof BASIC FIELD MANUAL 75 boxes with sufficient space to permit using the box either as a test station or as a terminal frame housing. Light wagons or trucks may be used to house centrals and telegraph stations. 60. Operation of telephones. — a. Two types of field tele¬ phones are in common use on field wire systems, the type EE-4-A and the type EE-5. In addition to these the service buzzer, type EE-63, can be used. b. These instruments have common operating characteristics but vary in details of construction. (1) The type EE-4-A telephone is equipped with a magneto for ringing, and a hand set, hung from a hook switch, for talking and listening. (2) The type EE-5 telephone is equipped with a magneto for ringing and a hand set for talking and listening. The push Figure 68. —Improvised shelter box for terminal strips button on the hand set must be pressed down while talking but should be released when one is merely listening, as it uses up the talking battery when depressed. (3) The service buzzer employs a buzzer call. The receiver is used for buzzer and telephone reception. A special telephone transmitter is provided. The push button switch on the trans¬ mitter must be pressed down while talking. This instrument should not be used for signaling a switchboard operator as its buzzer call interferes with all telephone conversations through his switchboard. 76 BASIC FIELD MANUAL c. Adherence to the following rules is essential for efficient telephone operation: (1) To signal the operator with a field telephone, turn the mag¬ neto crank several times, holding the instrument firing. Do not remove the hand set from hook when ringing on a type EE-4-A. Do not press the push button when ringing on a type EE-5 telephone. Lift the hand set from the hook or press the button while talking. When the switchboard operator answers the call, state the connection desired, for example “Magic—one- zero." When the called party answers, identify yourself and proceed with the conversation. (2) To answer a call on the telephone instrument, remove the hand set from the hook, or press down the button. Hold the hand set in a natural position with the head erect. Never say “hello" in answering. State the designation of the telephone and of the individual answering, for example “Magic—one- three speaking." (3) When through using the telephone or when it is desired to again attract the attention of the operator, replace the hand set on the hook, or release the button. Turn the magneto crank to “ring off," indicating to the switchboard operator that the con¬ nection may be removed, or that you want some other service from him. (4) Always speak directly into the transmitter mouthpiece. Speak distinctly and in a natural tone. Raise the voice slightly when necessary, but never shout. 61. Operating phrases. —The following phrases are pre¬ scribed for use by switchboard operators and should be used by them in all cases where they apply, to the exclusion of other phrases of similar meaning: a. “Magic operator." Used by operator at “Magic" in answering any incoming call, either from a local telephone or other centrals. b. “Captain Blank’s code number is Magic—four; 1 will con¬ nect you." Used by an operator when a call comes in by name or by some designation other than a telephone code number. c. “Waiting?" Used by an operator in challenging on a con¬ nection to determine whether the called party has answered and in supervising a connection. d. “Hello, Magic," or “Hello, Magic—three." Used by an operator when there is confusion or interruption on a connection through two or more centrals and he is trying to get a distant operator or called party back on the line. BASIC FIELD MANUAL 77 e. “Here’s your party.” Used by an operator whenever it is necessary for him to start the conversation over a connection. For example, if the called party should answer before the operator has connected him through to the calling party, the operator after completing the connection should start the conversation by using this phrase. /. “I can give you the message center.” Used by an operator in appropriate cases, after reporting that the called party’s tele¬ phone is out of order, the called party does not answer, or that the called party has no telephone; if the called party has no tele¬ phone but answers over another number this latter phrase does not apply. g. “I will ring again.” Used by an operator when he has cut in on an incompleted call and has been told that the called party did not answer. h. “What number were you calling?” May be used by an operator when a party calls and reports that he has been given a wrong number. In case a connection between two parties is broken before they have finished and either party tells the opera¬ tor that he was eut off from his party, the same phrase may be used. i. “Magic—one-one?” Used by operator in repeating the call to a calling party or another operator when such a call has been given him to put through. j. “Magic—one-one does not answer.” Used by an operator in reporting to the calling party that the called party does not answer. k. “Magic—one-four has no telephone.” Used by an opera¬ tor in reporting to the calling party that the called party has no telephone. l. “ Magic—one-one is busy.” Used by an operator in report¬ ing to the calling party that the called party’s circuit is busy. m. “ Magic—three-zero has no telephone, but I will give you Magic—one-one. You may get him there.” Used by an opera¬ tor when the called party has no telephone but can be reached over another telephone. n. “What number is calling?” Used by an operator if, after challenging, he has been given a new number to call. This phrase enables the operator to determine which one of the two parties previously connected is now requesting a new connection. 62. Operation of monocord switchboards. —The following procedure is prescribed for use by an operator in handling calls on a monocord switchboard. 78 BASIC FIELD MANUAL a. To make a local connection. Example. —Magic—three calls Magic—one-one. The telephone at Magic—three is connected to drop No. 2 and that at Magic—one-one to drop No. 5 on the switchboard. When the shutter on drop 2 falis, the operator’s plug is inserted into the jack on unit 2. The operator answers the call by stating his code designation, “Magic operator.” The calling party states the number desired, “Magic—one-one.” The operator repeats back “ Magic-^-one—one,” then removes the operator’s plug from the jack of unit 2 and inserts it into the jack of unit 5. He rings, then immediately inserts No. 5 plug into No. 2 jack. b. To make a trunk connection. Example .—Magic—one calls Mutton—one. The telephone at Magic—one is connected to drop No. 1 on the Magic switchboard. The circuit to Mutton passes through Maytime switchboard, and is connected to drop No. 7 on Magic switchboard. The circuit from Magic is con¬ nected to drop No. 3, and the circuit to Mutton to drop No. 4 at Maytime. When the shutter on drop No. 1 at Magic falls, the operator’s plug is inserted into No. 1 jack. The operator answers “Magic operator.” The calling party states,Mutton—one.” The Magic operator repeats back “Mutton—one,” then removes the operator’s plug from No. 1 jack, inserts it into No. 7, and rings. When the Maytime operator answers, the Magic operator states, “Mutton—one.” After the Maytime operator repeats back “ Mutton—one,” the Magic operator inserts No. 7 plug into No. 1 jack. The May time operator (at the intermediate switchboard) inserts his operator’s plug into his No. 3 jack when the shutter falls on the Magic operator’s signal, and answers the call, stating, “ Maytime operator.” The Magic operator states the connection desired, “ Mutton—one.” The Maytime operator repeats back “ Mutton—one,” removes the operator’s plug from No. 3 jack and inserts it into No. 4 jack and rings. When the Mutton operator answers, the Maytime operator states, “Mut¬ ton—one.” When the Mutton operator has repeated “Mut¬ ton—one,” the Maytime operator inserts No. 4 plug into No. 3 jack. The Mutton operator then handles the call as a local connection. c. To supervise a connection. —A switchboard operator super¬ vises each connection: (1) To insure that conversation is estab¬ lished between the calling party and the called party, and (2) to remove the connection as soon as possible after the conversation is completed. The operator listens in after making a connection, BASIC FIELD MANUAL 79 waiting to hear the called party answer and conversation begin. He then removes the operator’s plug and restores the shutter. Should another call enter his switchboard before he has super¬ vised this connection he removes the operator’s plug and answers this latter call. The shutter is not restored until he has gone back to the connection and supervised it. In supervising the first call, the operator inserts his plug into the jack of the called party and listens. If no conversation is heard he challenges by questioning, “ Waiting?” If he receives no response he takes down the connection. If he is notified that a called party has not answered, he answers, “I’ll ring again,” and proceeds to do so. If he receives an answer informing him that the connection is being used he removes the operator’s plug and restores the shutter. When a shutter falls on a completed connection, the operator inserts his operator’s plug into the jack corresponding to the fallen shutter and challenges by questioning “Waiting?” If he receives no response, he takes down the connection and restores the shutter. If a new number is given him, he repeats the new number and adds “What number is calling?” After receiving the number of the calling party he takes down the old connection and completes the new call in the usual manner. Connections that remain up for more than a reasonable time are supervised in a manner similar to the above method. d. To take down a connection .—The operator inserts his plug in the jack of the called party and listens. If no conversation is heard, he challenges “Waiting?” If no answer is received to the challenge, he removes both plugs and restores the shutters if down. 63. Records and reports.— At each telephone central, such records covering its operation are kept as may be necessary in preparing the required reports. These records may include a station log, a traffic diagram and test and trouble records. (See par. 72 for preparation of test and trouble records.) Reports on the operation are normally rendered to the signal officer through the message center. 64. Station log.— The station log should contain the fol¬ lowing information: Place, date, and hour station opened. Place, date, and hour station closed. Schedule of operators. Time of connecting or removing a circuit. Interruptions to circuits (duration and nature if known). 80 BASIC FIELD MANUAL This record is kept by the switchboard operator on duty, under the supervision of the chief operator. A simple blank form prepared for a station log is shown below, STATION LOG STATION:_ OPENED CLOSED PLACE DATE HOUR PLACE DATE HOUR • SCHEDULE OF OPERATORS CIRCUIT NO. TIME CONNECTS TIME REMOVED INTERRUPTIONS OF SERVICE NATURE OF REMARK5 FROM- TO- TROUBLE signature of chief operator Tl- 673 Figure 69. —Station log for a telephone central 85. Traffic diagram. — a. A traffic diagram shows by number the telephone channels connecting telephone centrals and distant local telephones in a net. The actual circuits connecting any BASIC FIELD MANUAL 81 two centrals are shown as one line with a figure indicating the total number of telephone channels between the two centrals. The units to which each switchboard or distant local belongs are indicated by the telephone code name and conventional sign of the unit. 6. Figure 70 shows a traffic diagram. c. The traffic diagram is prepared at each switchboard from data contained on the circuit diagram. Special symbols for this purpose are shown in paragraph 20. 66. Reports to message center.—The operating personnel should keep the message center informed of telephone communi- Figure 70.—Traffic diagram, 1st Division, 11 p. m., May 15, 1927 cation available to other centrals in the net. Interruptions and other changes should be reported promptly to the message center. Section IV INSTALLATION AND OPERATION OF FIELD TELE¬ GRAPH SETS AND STATIONS 67. The buzzer phone.— a. The buzzer phone, type EE-l-A, is a portable wire telegraph set, designed to provide an additional channel of wire communication over any existing field wire sys¬ tem. Its advantages are— 82 BASIC FIELD MANUAL (1) It provides an extra channel of communication over lines that at the same time carry telephonic communication without interference from buzzer phone, except when the call signal is used. (2) It may be operated by radio operators with little addi¬ tional instruction. (3) Its secrecy. Messages sent by buzzer phone can be inter¬ cepted only by a similar instrument cut in on the line. (4) It does not cause interference with other types of electrical signal communication, except with its call buzzer. Its disadvantage is that it does not work well over leaky or long lines. b. The buzzer phone can be used on ground return, metallic simplexed, or phantom circuits, except that v/hen more than two buzzer phones are to be connected to the same circuit, all of the stations are either connected between a line wire and ground or are bridged across a metallic circuit. c. To operate a buzzer phone, connect the line circuit to the L and G terminals. To call a distant operator press the switching key to the position marked call. This produces a highly induc¬ tive signal which interferes with telephone conversation, and therefore should not be used except during the minimum time required for calling. In the normal or nonoperating condition, the switching key is in the position marked normal. The re¬ ceiver is then across the circuit and will produce a signal when the distant operator calls with his call buzzer. After such a call signal is made or received, the switching key is moved to the send-receive position. Then, when the sending key is depressed, an audible signal is produced in the distant receiver. When the switching key is in the send-receive position and no signals are being sent, a steady tone in the receiver indicates a difference in potential between the two ground connections. A potenti¬ ometer is provided to compensate for this condition. Move the potentiometer key slowly to right or left until the tone is least apparent. 68. The service buzzer.— a. The service buzzer, type EE-63, is a combination telephone and telegraph instrument. (See par. 60 for use as a telephone.) When used as a telegraph instru¬ ment, messages are transmitted by producing a series of buzzes instead of the double clicks common to Morse telegraph sounders. (1) Its advantages are— (a) It may be operated by radio. operators with little additional instruction; BASIC FIELD MANUAL 83 (b) It works great distances over leaky lines; and (c) It is readily portable and very rugged. (2) Its disadvantages are— (а) The signals are readily intercepted; (б) It produces interference on neighboring electrical signaling equipment, and consequently cannot be used ordinarily over simplexed telephone circuits. b. The service buzzer may be operated over metallic or ground return circuits. The line circuit wires, or line circuit wire and ground, are connected to the L and G terminals, re¬ spectively. When the change-over switch is thrown to the buzz position, telegraph transmission is accomplished by working the key. Incoming signals are heard in the receiver, which is cut into the circuit wdien the sending key is up. If the buzzer is to be operated over existing Morse telegraph lines, the switch for short-circuiting the line condensers should be opened; this places the line circuit condensers in the line circuit of the service buzzer and prevents grounding the Morse telegraph circuit. 69. Simplex circuits.—Telegraph circuits used in field wire systems are obtained generally by simplexing the existing tele¬ phone circuits, thus eliminating the necessity for constructing additional circuits for telegraph purposes. Repeating coils are used for this purpose, as explained in paragraph 52. It is im¬ portant that the repeating coils be installed at the telephone terminal frame, rather than at the telegraph station, so that telephone trunk circuits, for the maintenance of winch the telephone line personnel is responsible, will not run through instruments or equipment for which the telegraph operating personnel is responsible. If the repeating coils were installed at the telegraph station, telephone trunk-line circuits would have to run from the telephone terminal frame to the telegraph station and back again to the same frame. With the repeating coil at the telephone terminal frame, only one wire is run to a terminal telegraph station from the “Tg” terminal of a repeating coil at that frame, this wire being the telegraph leg providing the wire connection to the telegraph circuit. The ground for the telegraph ground connection can be located at the telegraph office. Such a method saves time and line material, reduces possibilities of trouble on the telephone circuits, and facilitates the testing of the telephone circuits, without in any way inter¬ fering wdth the telegraph circuit. 84 BASIC FIELD MANUAL 70. Telegraph operating procedure. —Operating procedure for the buzzer phone and service buzzer follows radio procedure. (See ch. 3, Sec. II.) Section V MAINTENANCE OF FIELD WIRE SYSTEMS 71. General. —Field wire systems are subject to interruption due to injury or physical destruction and from defective circuit equipment. All such interruptions are termed troubles. Main¬ tenance of a field wire system includes the prevention, location, and correction of trouble in the system. Such maintenance is continuous. The means of preventing trouble and of locating it after it occurs in a field wire system are— a. Careful packing of all wire and equipment and careful handling while it is in use. b. Protection of equipment from moisture while in storage, in transit and, in so far as possible, after it is installed. c. Training of all operating and using personnel in the care and use of wire equipment. d. The inspection, cleaning, testing, and repair of the wire lines and associated equipment, when removed from storage for training or field service, and periodically during use. e. Special tests for wire and equipment found to be defective. /. Routing of wire lines and locating of centrals and stations so as to avoid hostile shell fire, and so as to protect the lines from the traffic of friendly troops or transport. Friendly tanks, balloon units, artillery, and tractors are especially destructive of wire lines. g. Establishment of test stations at important wire-line junctions and near points at which trouble is anticipated. 72. Periodic tests of line circuits and installed equip¬ ment. — a. Orders and instructions concerning the wire system usually include instructions relative to periodic tests and the frequency with which these tests are to be made. (See par. 17.) Tests of line circuits include the testing of the operating equip¬ ment connected to such circuits. b. Tele-phone line circuit testing. —(1) In the division or larger units frequent calls from the telephone central for the purpose of testing local telephone circuits and equipment may become a nuisance to the users. Such calls may be avoided by having a trouble man go to each local telephone and test back to the tele- BASIC FIELD MANUAL 85 phone central. In smaller units, where the number of main¬ tenance personnel is more limited, the local circuits are usually tested in the same manner as the trunk circuits. (See (2) below.) (2) Inasmuch as the telephone operator will generally not have time to make periodic tests, the wire chief should make such tests from his terminal frame. However, the operator may be called upon to make periodic tests when such testing does not interfere with the expeditious handling of traffic. (3) In making periodic tests at a point designated for testing telephone circuits, each circuit is first tested by ringing the party or central connected to it. If an answer is obtained, the test man TEST AND TROUBLE RECORD STATION_DATE_ Circuits tested every minutes CIRCUIT TESTED CLEARED REMARKS TIME BY TIME BY (Nature of trouble fikA • CHIEF OPERATOR 'TL-7E7 Figure 71.—Form for test and trouble record states the code name of his central, followed by “testing, thank you,” thus: “Surprise testing, thank you,” and then goes on to test the other circuits. A busy telephone circuit is not inter¬ rupted to make a test; the fact that it is busy shows that it is not in trouble. In case trouble is found on a circuit, the proper maintenance personnel is immediately given all available infor¬ mation as to the nature and location of the trouble. (4) Records of tests and troubles found on the trunk circuits are kept by the wire chief at each telephone central on the test 86 BASIC FIELD MANUAL and trouble record. (See pa#. 63.) This record gives the follow¬ ing information: (а) Frequency at which periodic tests are to be made. (б) For a circuit found to be in trouble; the number of the circuit, when and by whom tested, when and by whom cleared, and the nature and location of the trouble. A form for the test and trouble record is shown in Figure 71. c. Telegraph line circuit testing .—Periodic testing of telegraph circuits in a field wire system follows the same general princi- Figuke 72.—Universal test set, type EE-65 pies stated above for telephone circuits. The telegraph operator makes the tests and notifies the wire chief of the results. 73. Equipment used for testing. — a. The Signal Corps test set. —(1) Figure 72 shows the test set, type EE-65, which is an instrument designed to provide, in a compact portable form, circuit testing equipment particularly adapted to field use. The set can be used either in a vertical or horizontal posi¬ tion. If the voltmeter fails to read zero when all keys are in the normal, straight-out position, properly adjust the needle by means of the screw on the face of the voltmeter. The following BASIC FIELD MANUAL 87 tests which can be made with this test set are described as for line circuits. However, this test set is equally convenient in testing the circuits of Signal Corps wire equipment. For such tests, the frame of the instrument being tested is generally con¬ sidered as the ground. Before beginning any test be sure that all keys on the test set are in the normal or center position. In the following directions the keys are considered to be numbered from 1 to 5 from left to right. Prior to making any voltmeter tests with this set the voltmeter battery of the set should be tested by moving No. 4 key to the BAT position. The voltmeter will then indicate the voltage of the voltmeter battery. This battery consists of two BA-2 batteries connected in series and, if new, should register 45 volts. If BA-2 batteries are not available, other batteries, con¬ nected to give from 40 to 50 volts, may be connected to the bind¬ ing posts marked EX BAT. When using external batteries remove the BA-2 batteries from the set. The cylindrical BA-1 battery of the test set, used as the transmitter battery, should also be tested by removing it from the set and proceeding as in. (3) below. (2) Circuit tests. —These tests are described in the order they are made during the normal testing of circuits in trouble. (а) Ringing and talking test.— Connect the ends of the tele¬ phone circuit under test to the Li and L 2 binding posts on the test set. If the circuit is a ground return cir¬ cuit, connect Li to the metallic side of the circuit and L 2 to ground by means of the ground rod and its lead. Adjust the receiver to the ear so that it is held com¬ fortably in place by means of the elastic band. Operate No. 1 key to the RING position. Turn the generator crank through at least three complete turns. Then operate No. 1 key to LISTEN position. If the called party answers, press the button on the trans¬ mitter; conversation may then begin. After conver¬ sation has been completed, return No. 1 key to its normal position. (б) Test for a complete short or open circuit. —Connect the ends of the metallic or ground return circuit under test to the Li and L 2 binding posts on the test set. Oper¬ ate No. 3 key to the VMB position. If the circuit is complete the voltmeter will give a continuous reading; if open, there will be no continuous reading. If a ground return circuit is to be tested at a place where 88 BASIC FIELD MANUAL the lead to the ground connection of the circuit is not available, connect the metallic side of the circuit to the Li binding post on the test set and make certain that the test set binding post marked GND is connected to ground by means of the ground rod and its lead. Operate No. 3 key to the VMG position. If the cir¬ cuit is grounded, the voltmeter will give a continuous reading; if open there will be no continuous reading. Upon completion of these tests, return No. 3 key to normal position. (c) Test for a condenser .—If in the test described in (6) above a circuit tests open, leave No. 3 key in the VMG position and operate No. 2 key several times between its normal and LR positions. If there is a condenser across the circuit there will be a voltmeter reading only while the key is being operated. If this test shows a condenser across the circuit, there is probably an EE-4-A telephone or other instrument with a condenser across the line circuit. An EE-5 telephone, or a monocord or camp switchboard con¬ nected to a line circuit, shows a complete circuit. The set can be calibrated by reading the deflection on lines having one bell and condenser, two bells and two condensers, and so on. The condenser at the station is charged and then discharged by the opening and closing of the circuit under control of key No. 2. id) Test for a grounded circuit .—Connect the ends of the cir¬ cuit to be tested to the Li and L 2 binding posts on the test set. Make certain that the GND binding post on the set is connected to ground. Operate No. 3 key to the VMG position. A voltmeter read¬ ing indicates a ground on the circuit. If the circuit tested open in the test for an open circuit, the circuit wire connected to the Li binding post is grounded. Leaving No. 3 key in the VMG position, operate No. 2 key to the LR position to reverse the connections of the external circuit. If the circuit previously tested open, a voltmeter reading then indicates a ground on the circuit wire connected to the L 2 binding post. Upon completion of the test for a grounded circuit, return No. 2 and No. 3 keys to normal posi¬ tion. BASIC FIELD MANUAL 89 (e) Test for a cross with another circuit .—Connect the ends of the circuit under test to the Li and L 2 binding posts on the test set. Connect one wire of the circuit with which the circuit under test is believed to be crossed to the GND binding post on the set. Be sure that for this test the ground binding post is not grounded. Operate No. 3 key to the YMG position. A voltmeter reading indicates a cross between the circuit wire connected to the Li binding post and the circuit wire connected to the GND binding post. To test for a cross between the circuit wire connected to the L 2 binding post, and the wire connected to the GND binding post, operate No. 2 key, down, to the LR position, leaving No. 3 key in the VMG position. A voltmeter reading indicates a cross. Remove the wire connected to the GND binding post, connect the other side of this other circuit to the GND binding post and repeat above tests to determine if either side of the circuit under test is crossed with this second wire of the other circuit. Upon completion of these tests, return No. 2 and No. 3 keys to normal position. (3) Measuring voltage of a battery. —Connect the battery to the terminals marked BAT TEST. Be sure to have the positive terminal of the battery connected to the plus ( + ) or left-hand binding post. Operate No. 5 key to the EX BAT TST position. The voltmeter is thereby connected across the terminals of the battery. The voltage of the battery can be read from the volt¬ meter scale. Do not make this measurement on a battery whose voltage is likely to be greater than the maximum-voltage reading of the voltmeter scale. b. Field telephone, type EE—J+—A, as a test instrument. —This type of field telephone may be used for testing line or instrument circuits. Prior to using a particular telephone for testing, it should be tested as described in paragraph 81 b to determine whether the instrument is in operating condition.- In using the telephone for test purposes it is essential that the feel of the hand- generator crank of the telephone used in making the test be known. The manner in which it turns on ringing over an open circuit, a short circuit, a complete circuit to which another serviceable telephone or switchboard is connected, and for a grounded circuit in the case of a ground-return circuit, should be determined prior to its use for testing purposes. The following tests may be made with this type of telephone: 90 BASIC FIELD MANUAL (1) Ringing and talking test. —Connect the ends of the tele¬ phone circuit to be tested to the Li and L 2 binding posts of a serviceable telephone. If the circuit to be tested is a ground- return circuit, connect L x to the metallic side of the circuit and L 2 to ground by means of a ground rod and lead. Move the hook-switch lever out and suspend the hand set from it. Turn the hand-generator crank through at least three complete turns. If the line circuit and the signaling apparatus of the distant instrument are in serviceable condition, the crank should turn with a slight drag. Remove the hand set from the hook switch and place the receiver to the ear, holding the head vertical in a normal position with the transmitter before the mouth. If the called party answers, and can hear, the test shows that both the line circuit and the instruments are in serviceable condition. After conversation has been completed, return the hand set to the hook switch and turn the hand-generator crank through at least one complete turn, to ring off. (2) Test for an open circuit. —Connect the ends of the metallic or ground return circuit to be tested to the Li and L 2 binding posts on the telephone. Leaving the hand set suspended from the hook switch, turn the hand generator crank through at least three complete turns. If the circuit is open the bells should ring and the crank should turn freely without any drag. (3) Test for a short circuit. —Connect the ends of the metallic or ground return circuit to be tested to the Li and L 2 binding posts on the telephone. Suspend the hand set from the hook switch and turn the hand generator crank through at least three com¬ plete turns. If the circuit is short, the crank should turn with difficulty as though a heavy drag had been placed on it, and the bells should not ring. (4) Test for a grounded circuit. —Connect one side of the metallic circuit to be tested to the Li binding post of the tele¬ phone. Connect the L 2 binding post to ground by means of a ground rod and lead. With the hand set suspended from the hook switch, turn the hand generator crank through at least three complete turns. If the circuit wire connected to the Li binding post is grounded, the results noted upon turning the crank will be the same as for a short circuit, i. e., the crank should turn with difficulty and the bells should not ring. Remove the circuit wire connected to the Li binding post and connect the other side of the circuit to Li. Repeat the above test to determine if this side of the circuit is grounded. To test a ground return circuit BASIC FIELD MANUAL 91 for a ground, have the circuit opened at the distant end and then test as described above. (5) Test for a cross with another circuit. —Connect one side of the circuit to be tested to the Lj binding post of the telephone. Connect one wire of the circuit, with which the circuit under test is believed to be crossed, to the L 2 binding post on the telephone. Make a test for a short circuit, outlined in (3) above. If these two wires are crossed, the test should indicate a short circuit. If the two wires are not crossed, the test should indicate an open circuit. Remove the circuit wire from the L 2 binding post, connect the other side of the same circuit to that binding post, and repeat the test. Next remove from the Li binding post the circuit wire being tested and connect the other side of this Figure 73. —Voltmeter and battery connected for use in testing circuits circuit to Li. Repeat above test to determine if this side of the circuit being tested is crossed with either of the wires in the other circuit. c. Field telephone, type EE-5, as a test instrument. —The methods of testing with this type of telephone are the same as with the field telephone, type EE—4-A, with the following modi¬ fications: (1) A buzzer is used for signaling purposes instead of a bell and it should never operate when the hand generator crank is turned; and (2) Substitute L for Li and G for L 2 . d. Voltmeter and battery used in testing. —Figure 73 shows a voltmeter and battery connected in series and equipped with wire leads. This provides a simple arrangement for testing equipment circuits. The terminals of the wire leads may be 1143°—31-4 92 BASIC FIELD MANUAL fitted either with test clips or short lengths of stiff copper wire for convenience in making contacts with the equipment circuits. This apparatus is suitable for making the following tests: (1) Test for a complete circuit. —Connect the test leads to the ends of the circuit to be tested. Complete the circuit by depres¬ sing the push-button switch on the voltmeter. If the circuit is complete the voltmeter needle will indicate a reading. (2) Test for an open circuit. —Connect the test leads to the ends of the circuit to be tested. Complete the circuit by depressing the push-button switch on the voltmeter. If the circuit is open, the voltmeter needle will not indicate a reading. (3) Test for a short circuit. —Connect the test leads to the ends of circuit to be tested. Open the other end of the circuit. Com¬ plete the circuit by depressing the push-button switch on the voltmeter. If the circuit tests short, the results will be the same as for a complete circuit; i. e., the voltmeter needle will indicate a reading. (4) Test for a grounded circuit. —Connect one test lead to the circuit to be tested. Connect the other test lead to ground. Complete the circuit by depressing the push-button switch on the voltmeter. If the circuit is grounded, the results noted will be the same as for a complete circuit, i. e., the voltmeter needle will indicate a reading. (5) Test for a cross with another circuit. —Connect one test lead to the circuit to be tested. Connect the other test lead to the circuit with which the circuit to be tested is believed to be crossed. Complete the circuit by depressing the push-button switch on the voltmeter. If the circuit is crossed with the other circuit, the results noted will be the same as for a continuous circuit; i. e., the voltmeter needle will indicate a reading. e. Receiver and battery used in testing. —Figure 74 shows a tele¬ phone switchboard receiver connected in series with a battery and fitted with leads for testing. The terminals of the test leads may be equipped either with test clips or short lengths of stiff copper wire. The apparatus is suitable for making the tests out¬ lined for the voltmeter and battery in d above. However, in¬ stead of a reading indicating a complete circuit, in this case when the circuit is completed by touching or connecting the test leads, a click in the receiver indicates a complete circuit. A failure to obtain a click on completing the circuit indicates an open circuit. BASIC FIELD MANUAL 93 74. Testing defective line circuits—locating and clear¬ ing trouble. —Defective line circuits are tested and their trou¬ bles are located with the aid of testing equipment employed in the general manner laid down in paragraph 73. The special sup¬ plementary procedures applicable for locating the various line circuit troubles are set forth below. a. Telephone line circuits .—A trouble developing in a telephone line circuit is detected either by telephone personnel while making prearranged tests or by a telephone operator or user when the circuit fails to give satisfactory service. In either case the trouble should be reported immediately to the chief operator, Figure 74.—Receiver and battery connected for use in testing circuits wire chief, or other individual detailed to handle such cases, who proceeds as follows: (1) A short local circuit in trouble. (a) First determine the nature of the trouble, i. e., whether open, short, ground or cross, by tests described in paragraph 73. If the trouble is caused by an open; place a short on the defective circuit at the line side of the line portion of the circuit leading to the switchboard. If the trouble appears in this part of the circuit, short the circuit at the switchboard side of the switchboard terminal strips and repeat the test. If this test shows an open circuit, place a short at the switchboard line terminals and again repeat the test. If it is deter¬ mined that the trouble is in the switchboard, test the fuses, jack, and drop unit as described in para¬ graph 82. If the trouble is caused by a short, 94 BASIC FIELD MANUAL ground, or cross, open the defective circuit at the line board side of the line terminal strip and test that portion of the circuit toward the switchboard. If the trouble is in this part of the circuit, open the circuit at the switchboard terminal strip and repeat the test. If the trouble is still present, open the circuit at the line terminals of the switchboard and repeat the test. If the trouble is in the switch¬ board, test the fuses and drop unit as described in paragraph 82. If the trouble is in the terminal strip, either repair or change to another pair of binding posts on the strip. If the trouble is in the cable, substitute a spare pair for the unserviceable pair. If the trouble is in the fuses, replace the defective fuses. If the trouble is in the drop circuit, either connect the circuit to another drop circuit on the switchboard, or in the case of a monocord switchboard, replace the unserviceable unit with a serviceable unit. In any of the above tests, make ringing and talking tests, test for a short and open circuit, test for a grounded circuit, and, if applica¬ ble, test for a cross with another circuit. It is always proper to assume that the trouble may lie within the equipment of the telephone central, and time will generally be saved by first testing this side of the circuit. (6) If, upon making the first test described above at the line terminal strips, the trouble is found to be to¬ ward the user’s telephone, reconnect the circuit, if opened, and dispatch a troubleman with a service¬ able telephone, to the user’s instrument. On his way he should inspect the circuit for visible sources of trouble and repair any that he finds. He should then make a ringing and talking test with the user’s telephone. If he can not signal the operator with it, he should replace the local instrument with his own instrument, and repeat the test. If he can now signal and converse with the operator, the trouble was in the local telephone which should be tested as in paragraph 81, and either repaired or replaced. If he can not signal the operator, the trouble is probably in the local line circuit, and he BASIC FIELD MANUAL 95 should first test for a short and an open circuit, then test for a grounded circuit, and if applicable, test for a cross with another circuit. If trouble is located in the line wire, work back toward the tele¬ phone central, testing at frequent intervals until the trouble is found. (c) After trouble has been located and cleared, notify the user that the service is again available. (2) Trunk circuits in trouble . (a) Determine the nature of trunk circuit trouble and „ whether it is in the telephone central or outside thereof in the same manner as described for local circuits, and if the trouble is found to be inside, locate and repair. Proceed as in (1) (a) above. If the trouble is found to be outside, proceed as out¬ lined below. ( b) An open circuit .—If an additional circuit is available call the distant operator and request him to place a short on the defective circuit at the line terminal strip. If this short completes the circuit, it indi¬ cates that the circuit between the two centrals is : in order and that the trouble is at the distant central. So inform the distant operator and request him to have the trouble cleared. If the short does not complete the circuit, the trouble is between the tw'O centrals, in which case a lineman should be dispatched to locate and clear the trouble. If an additional circuit is not available, send a lineman out on the defective circuit to locate and clear the trouble. In either case the lineman proceeds as outlined in ( d ) below. (c) A short or grounded circuit .—If an additional'circuit is available, call the distant operator and have him open the defective circuit at the line terminal strip. If this clears the circuit it indicates that the circuit between the two centrals is in order and that the trouble is at the distant central. Inform the distant operator to this effect and request him to have the trouble cleared. If the open does not clear the circuit, the trouble is between the two centrals, in which case a lineman should be dis¬ patched to locate and clear the trouble. If an 96 BASIC FIELD MANUAL additional circuit is not available send a lineman out on the defective circuit to locate and clear the trouble. In either case the lineman proceeds as outlined in (d) below. (d) The wire chief should determine as accurately as his instruments permit the approximate location of the trouble. This will facilitate the testing and materially shorten the time required to locate and clear the trouble. The lineman, starting at the telephone central, carefully examines the circuit as he proceeds on his inspection, particularly scru¬ tinizing the insulation, splices, underground and overhead road crossings and places where the wire has been passed over or pulled out of place by traffic. Fouled insulation, poor splices and other evidences of possible trouble should be repaired and the circuit tested in order to determine if the trouble has been cleared. The lineman in testing the defective circuit for an open connects his testing equipment across the circuit without opening it. To test for a short or grounded circuit he opens the circuit and then tests in both directions. On completion of the test the circuit is reconnected. In case it is neces- . sary to open the circuit it should be done at a splice or at a test station, if practicable. ( e ) A defective circuit may have more than one case of trouble. These may be of the same nature or different. It is essential that the lineman, after clearing a case of trouble, test the circuit in both directions to insure that it is in order. If trouble still exists he continues his inspection until all trouble has been located and cleared. b. Telegraph line circuits .—Field telegraph instruments are operated either on circuits used only for wire telegraphy, or on simplexed telephone circuits. Personnel testing a defective telegraph circuit should be equipped with testing equipment with which they can communicate with each other or with a telegraph office. Telegraph line circuits are subject to the same troubles as are telephone line circuits. Such troubles are located and cleared in a similar manner, the method of making the different tests being governed by the testing equipment em- BASIC FIELD MANUAL 97 ployed, and modified as necessary when a telegraph sending and receiving instrument is made a part of the testing equipment. c. Locating and clearing trouble on defective circuits which pass through test stations manned by linemen are facilitated by the fact that the wire chief can call each successive test station operator and quickly determine the section of the line in which the trouble lies, as explained in paragraph 75. The nearest test station can then be directed to dispatch a lineman to definitely locate and clear the trouble. In the meantime serviceable sec¬ tions of two or more unserviceable circuits can be patched through a test station, to provide at least one complete service¬ able circuit out of sections of two or more unserviceable circuits, as described in paragraph 76. 75. Operation of test stations.— (See also par. 37.) The personnel at a test station consists of one or more linemen, as the situation requires. A test telephone is kept bridged across a circuit, usually the lowest numbered telephone circuit passing through the test station, or on a special circuit ending at the test station and temporarily reserved for test purposes. The per¬ sonnel on duty at the test station is instructed to answer pre¬ arranged signals, usually three rings only. When this pre¬ arranged signal is answered, the test station personnel should give the name of the test station. For example, “Knob Hill Test.” The test station personnel may then be instructed as to patching, testing, or repairing, as the situation requires. A copy of the circuit diagram and line route map indicating all circuits passing through or ending at the test station is kept posted at the test station. 76. Patching circuits at test stations. —The patching of circuits at test stations frequently results in maintaining com¬ munication between centrals over these patched circuits during the locating and clearing of trouble on the defective sections of the original circuits. If this patching were not done, com¬ munication would be interrupted until the trouble had been cleared. The example given herewith illustrates a case where patching may be used advantageously. Assume that two tele¬ phone centrals are connected by three circuits, all of which pass through two test stations, as shown in Figure 75. The telephone switchboard operator at Magic reports to the Magic wire chief that circuits 102 and 103 to May time are out of order. The wire chief at Magic tests these two circuits with the aid of a serviceable circuit to his test stations. He finds that the trouble on the 102 circuit lies in section 202, between Test A and Test B; 98 BASIC FIELD MANUAL and that the trouble on the 103 circuit lies in section 303 between Test B and Mavtime. He then instructs the lineman at Test B to remove the jumpers connecting circuit 202 to circuit 302, and circuit 203 to circuit 303; and to jumper circuit 203 to circuit 302, and circuit 202 to circuit 303. This gives immediately one built-up circuit from Magic to Maytime in addition to the 101- 201-301 circuit. Until the trouble on the twm defective sections (202 and 303), which are now in one circuit, has been located and cleared this built-up circuit (102-202-303) will be available, and the Magic wire chief advises the linemen at Tests A and B and the Maytime wire chief of the changes so that all circuit diagrams can be temporarily changed accordingly. When the interrupted circuits have b£en repaired the wire chief is notified. Upon instructions from him the original connections will be re- MAGIC A 6 MAYTIME TL-730 Figure 75. —Circuits patched at a test station stored during an interval between busy periods of the patch circuit and all concerned notified to this effect. 77. Patrolling wire lines. —In shelled areas or where wire lines are subject to frequent damage from other causes, periodic testing from designated points is supplemented by patrolling the sections most subject to damage. Whenever possible, the personnel that has constructed a given section is also assigned the mission of patrolling that section. Wire patrols, to be ef¬ fective, must carefully inspect every foot of the wire in the sec¬ tions they cover. This is made possible by the use of the wire pike or an improvised wire guide made by fastening a bridle ring to a hand grip. Wire patrols repair trouble whenever found. They replace doubtful splices or sections of the line, tape abra¬ sions in insulation, and wherever possible they improve the con¬ struction. 78. Testing field wire on reels. —All insulated wire must be carefully reconditioned after use, as follows: a. Mount an empty reel and the reel containing the wire to be tested, so that the wire may be wound from the full reel onto the empty reel. BASIC FIELD MANUAL 99 b. Pass the end of the wire through the hole provided near the drum of the empty reel and secure it so that the end will pro¬ trude from the side of the reel. This end must be free for use in future testing. c. Station an experienced man between the reels to carefully examine the wire as it is slowly wound onto the empty reel. Cover with tape each abrasion or break in the insulation. If only the braid is broken, apply one layer of friction tape. If the bare wire is exposed, remove the ragged portions of insula¬ tion and cover the wire with two layers of friction tape as de¬ scribed in paragraph 25 b (1). Carefully splice breaks in the conductor. Untape and examine each old splice; if the splice is poorly made, cut it out and splice the wire properly. If the insulation has been damaged over a long section of the wire, or if there are several splices very close together, cut out the faulty section. d. After each splice, and also when all the wire of a reel is completely repaired, test the wires on the reel being filled for an open circuit and a short circuit or for a cross between the two wires if the wire is of a twisted pair type. These tests may be made by any of the equipment used for testing as described in paragraph 73, by applying the tests in the manner prescribed therein. 79. Terminal strip. —Terminal strips are subject to failure as a result of abuse, corroded or dirty contacts, or of loose bind¬ ing posts. Screws which pass through the block connect the binding posts to metal connecting strips. If these screws be¬ come loose, poor contact results between the binding post and the strip with which it should make contact. To tighten a loose binding post, remove the sealing wax from around the end of the screw at the back of the block and tighten the screw; then reseal with sealing wax. A loose binding post of a terminal, type TM-84, may be tightened without removing the wax from the back of the screw, by holding fast to the round nut of the binding post next to the strip, and then turning the stem of the binding post in a counterclockwise direction by means of pliers. In performing this operation, the wing nut should be on its stem as this operation sometimes strips some of the top threads of the stem, making it difficult to replace the wing nut if previously removed. This method is particularly applicable when the trouble occurs after a terminal strip is already installed. During the inspection, clean and brighten the contact surfaces 100 BASIC FIELD MANUAL of the binding posts with sandpaper or emery cloth. After cleaning and tightening them, make a test for an open circuit, as in paragraph 73, or connect a telephone to each side of the top pair of strips and ring between telephones. Next, while listening at one telephone, try to move each of the four binding posts of each pair of strips; a loose terminal will produce a grat¬ ing noise in the receiver. If trouble develops, repair as indi¬ cated above. Repeat this test for each pair of strips on the block. 80. Primary batteries.— (See also ch. 3, Sec. XI.) The source of electrical power used to operate all equipment of a field wire system is obtained from primary batteries (dry batteries). Inefficient operation of wire equipment is often due to weak or run down batteries. a. An excellent indication of the condition of a primary battery is its voltage while it is in normal use. If a dry battery can not be conveniently tested while in use, its voltage when not in use (open circuit test) gives some indication of its condition, although a dry battery may give a satisfactory voltage reading with the open circuit test but may be unserviceable. (1) The voltage of a battery can be tested by means of a port¬ able voltmeter, or by making use of the voltmeter in the universal test set, as described in paragraph 73a (3). In either case care must be exercised to connect the positive terminal of the battery to the positive ( + ) binding post of the voltmeter or test set, and the negative terminal of the battery to the negative ( —) binding post of the instrument. (2) The normal open circuit voltage of each of the primary batteries used in field wire systems is given in the following table. The closed circuit voltage of a dry battery in good condition should be very little less than its open circuit voltage when the battery is in a use for which it was intended. The open circuit voltage of any dry battery in good condition is approximately 1.5 multiplied by the number of cells in the battery. Battery type Identification of terminals Open- circuit voltage Positive Negative BA-1... Top, center_ __ Zinc case.. 3.1 BA-2__ Red---..-_ Black... 22.5 BA-8_ do do_ 22.5 BA-9__ Short strip Long strip __ 4.5 BA-17_ . . Top, center . Zinc case 1.5 BASIC FIELD MANUAL 101 b. If a voltmeter is not available for testing a dry battery it should be tested in the instrument in which it is normally used. A battery should give satisfactory results when used with such an instrument. 81. Field telephones. — a. General .—While in use, poor operation will normally be reported by the users, but in order to maintain the confidence of the users of the system it is necessary that all equipment be in good operating condition at the time of installation and continuously thereafter. The signal communica¬ tion personnel should, therefore, by periodic tests and necessary repairs of the telephones, make certain that at all times they are in the most serviceable condition possible. When telephones are removed from an installation they should be tested as to NORMAL POSITION TL-730 CLOSED 'Figure 76.—Hook switch in telephone, type EE-4-A their operating condition, and necessary repairs should be made before they are again installed or stored. b. Field telephone , type EE~4~A .—Make certain that a service¬ able battery is in the battery compartment. (1) Test the hook switch. Fold the hook switch lever out, and move it up and down. The lever when released should move up; in so doing it should make two contacts, as shown in Figure 76 a. When it is pulled down these two contacts should break, as shown in Figure 76 b. While the hook switch lever is folded in, as when the telephone is not installed, the contacts should break, as shown in Figure 76 c. (2) Test the transmitter and receiver circuits. (a) Short the line terminals, I>! and L 2 . (See fig. 77.) Blow lightly into the mouthpiece; if the talking circuit is in good operating condition, this sound or side tone should be heard in the receiver. If this side tone is not heard, or is weak, a fresh battery should be installed and the test repeated. If this 102 BASIC FIELD MANUAL side tone still is not heard the talking or receiver circuit is in trouble and the telephone should be repaired by a trained repairman. Ability to deter¬ mine the serviceability of the talking circuit by this test is acquired only by constant practice in com¬ paring the strength of such sounds in different types of telephones, then by comparing the operating efficiency of the various telephones tested, when they are in use on long circuits. (6)^If the tests in (a) above show the talking or receiver circuit to be in trouble, this trouble can be more definitely located by connecting the telephone being tested to a serviceable telephone and testing as fol¬ lows: Release the hook switch of each telephone. Blow into the transmitter of the good telephone. If the side tone is heard in the receiver of the tele¬ phone under test, the receiver circuit of this tele¬ phone is in working order. Blow into the trans¬ mitter of the telephone under test. If the side tone is heard in the receiver of the good telephone, the transmitter circuit of the telephone under test is in working order. BASIC FIELD MANUAL 103 (3) Test the signaling circuit. (a) When the crank of the hand generator is turned the bell in the telephone should ring and the crank should turn easily. ( b ) Moisten the ends of the fingers and touch the two line terminals, Li and L 2 , and at the same time slowly turn the crank of the generator. A shock should be felt in the fingers. (c) Short the line terminals of the telephone and turn the crank. The crank should turn hard, as though a drag had been placed on it, and the bell should not ring. ( d) If any of the above tests fail, the ringing circuit is un¬ serviceable and the telephone should be repaired by a trained repairman. c. Field telephone , type EE-6. —(1) This telephone has a push button in the hand set instead of a hook switch in the set box, as in the telephone, type EE-4-A. It is so connected that the user can hear without depressing the push button, but in order to transmit, the push button must be depressed. To test the push button depress and release it. If it returns to its normal position, it is probably in a serviceable condition. (2) Test the talking and receiving circuit. (а) Short the line binding posts L and G and depress the push button. Blow lightly into the transmitter. The side tone should be distinctly audible in the receiver. If no side tone is heard, install a new battery and repeat the test. If this does not alter the result, the talking or receiver circuit is in an unserviceable condition. (б) If the tests in (a) above show the talking or receiver circuit to be in trouble, this trouble can be more definitely located as follows: Connect a serviceable telephone to the telephone under test, depress the push button of the telephone under test and blow lightly into the transmitter; if a side tone is dis¬ tinctly audible in the receiver of the serviceable telephone the talking circuit of the telephone under test is serviceable; if not distinctly audible the talking circuit is unserviceable; depress the push button of the serviceable telephone and blow lightly into the transmitter; if the side tone is dis- 104 BASIC FIELD MANUAL tinctly audible in the receiver of the telephone under test the receiver circuit is serviceable; if not, it is unserviceable. (3) Test the ringer circuit. (а) Turn the crank of the hand generator. It should turn easily and the buzzer should not operate. (б) Moisten the ends of the fingers and touch the line binding posts L and G and at the same time slowly turn the crank of the hand generator. A distinct shock should be felt in the fingers, its intensity depending upon the rapidity with which the crank is turned. (c) Short the line binding posts L and G and turn the crank of the hand generator. The crank should turn hard as though a drag had been placed upon it and the buzzer should not operate. (d) Connect the telephone under test to a serviceable telephone. Turn the crank of the hand generator of the telephone under test. The buzzer in the serviceable telephone should operate. Turn the crank of the hand generator of the serviceable tele- BASIC FIELD MANUAL 105 phone. The buzzer of the telephone under test should operate. (e) In the event that a serviceable telephone is not avail¬ able, the telephone under test may be removed from the leather case and the make and break contacts of the generator shunt switch short-circuited with a screw driver or knife blade. When the generator crank of the telephone is turned, its own buzzer will operate if it is in serviceable condition. (/) If any of the above tests fail, the telephone is unservice¬ able and should be repaired by a trained repairman. 82. Monocord switchboards. — a. Before removing the monocord switchboard from the supply room for installation, and immediately upon installation, the following inspections and tests should be made: (1) Set up the switchboard vertically in an operating position and release its shutter locks. (2) Inspect the switchboard for damaged or missing parts. (3) Connect a dry cell across terminals B and Bi as shown in Figure 79. (4) Connect a low resistance buzzer or bell across terminals A and Ai. (5) Connect a serviceable magneto telephone to terminals Li and L 2 . b. Tests and troubles .— (1) Operator's cord circuit. (a) Turn the hand generator of the telephone. The crank should turn easily. If the generator crank does not turn easily, the trouble is due probably to a short circuit in the plug or at the cord fasteners. {fi) Short-circuit the operator’s plug and again operate the hand generator. The crank should turn hard. If the crank does not turn hard, the trouble is due probably to an open in the plug connections or cord or at the cord fasteners. (2) Switchboard units, type EE-2. (a) Place the operator’s plug between the line terminal binding posts of unit No. 1, so that the tip makes contact with one binding post and the sleeve with the other. Turn the hand generator of the Figure 79.—Mono- cord switchboard, type BD-9 106 BASIC FIELD MANUAL telephone. The generator should turn easity. The shutter of the unit should fall and the night alarm buzzer or bell should operate. If the generator crank turns hard, the trouble is due probably to a short circuit either in the unit plug, at the cord fasteners, between the line terminals and lightning arrester, or at the jack. If the crank turns easily and the drop fails to fall, the trouble is due probably to an open fuse, drop out of adjustment, contact spring out of adjustment, or to an open connection at the jack, at the drop, or within the drop. If the trouble can not be located by inspection, test each section of the wiring with a voltmeter and dry cell, or with a dry cell and receiver connected in series. See Figures 73 and 74 for connections. (6) Insert the operator’s plug into the jack of unit No. 1. Short-circuit the line binding posts and operate the hand generator. The crank should turn hard. If the crank does not turn hard, the trouble is due probably to a failure of the plug to make contact in the jack. (c) Remove the short from the line circuit binding posts. Short-circuit the tip and sleeve of plug No. 1 and again operate the hand generator. The crank should turn hard. If the crank does not turn hard, the trouble is due probably to an open in the plug, cord or at the cord fasteners. (d) Test the other units in the same manner. (e) If trouble develops in any unit that can not be readily repaired, replace the unserviceable unit with one that is serviceable. 83. The buzzer phone. —The buzzer phone, type EE-l-A, is a very well made instrument which will give good service if not tampered with. The only permissible servicing consists in keeping the battery springs and contacts clean and bright, and in making necessary adjustments in the call buzzer as described in a below. a. To adjust the call buzzer, loosen the locking screw, back off the contact screw, and turn the vibrator adjusting screw until the armature on the end of the vibrator stands in the center of the gap in which it moves. Press the switch key on the top of the panel to CALL and turn the contact screw in BASIC FIELD MANUAL 107 VIBRATOR SCREW) LOCK SCREW VIBRATOR until a strong and positive note is obtained. The locking screw should then be set tight. b. To test the buzzer phone for secrecy, connect its terminals to those of a second buzzer phone whose switch key is in the STAND-BY position. Put the switch key^ of the first buzzer phone in the SEND-RECEIVE position and operate the key while listening in the receiver of the second. In this case no tone or clicks should be heard until the switch of the second buzzer phone is moved to SEND-RECEIYE. c. The sending key should have no side play. It should have at least one-thirty-second of an inch opening at the front contact. The lock nuts on the key and the nuts under the base, which clamp the ends of the receiver cords, should be tight at all times. d. The battery adjacent to the coils in the set box is the one which operates the set. It is exhausted much sooner than the potentiometer battery. If the operating battery becomes exhausted, it may in an emergency be exchanged with the potentiometer battery, which is not so impor¬ tant in the operation of the set. e. In case the buz¬ zer phone fails to op¬ erate, no field repairs can be made beyond ascertaining if any connections on the bottom of the panel have worked loose or broken off or if replacement of batteries is necessary. 84. The service buzzer. — a. The battery chamber .—The bat¬ tery chamber of the service buzzer, type EE-63, is a frequent source of trouble unless it is kept clean. The tips of the conical springs at the bottom of the battery chamber and the brass con¬ tacts on the door should be kept bright and free from any signs of corrosion. b. The key .—The key, Figure 81, is pivoted between two trunnion screws, which should be so adjusted and locked by the set nuts that the front contact on the key lever mates exactly with the contact on the base and not to the right or left of it. They should be kept tight enough to eliminate side play of the key lever without restricting its up-and-down movement. The spring screw is adjusted to suit the individual operator; the upper TU-673 Figure 80.—Call buzzer adjustments of buzzer phone 108 BASIC FIELD MANUAL contact screw should be up far enough to insure a positive break at both contacts under the key when the key is up. c. The vibrator .—The vibrator is adjusted by loosening the lock screw, backing off the contact screw and turning the vibra¬ tor screw until there is a gap of about one and one-half times the thickness of the vibrator between it and the core of the in¬ duction coil. The contact screw r should then be turned in and clamped by the lock screw at the point where a clear and strong note is obtained when pressing the key. If the vibrator clicks on working the key, even when the contact screw is backed off, the vibrator condenser is short-circuited. If the vibrator Figure 81.—Top view of service buzzer operating panel sparks excessively and there is no change in tone on removal of the vibrator condenser, the condenser is open. When trouble is experienced with the vibrator condenser, it may be replaced in an emergency by one of the other two condensers which are not so essential to the operation. d. Transmitter and receiver .—The cord tips should be firmly clamped on the binding posts and in such positions that there is no danger of their touching either each other or the metal frame of the case. To test the transmitter and receiver, throw the knife switch to talk T, short-circuit the line terminals, press the button on the side of the transmitter, and blow into the trans¬ mitter. A distinct audible sound should be heard in the re- BASIC FIELD MANUAL 109 ceiver. On connecting one terminal only to one terminal of of another buzzer, signals should be heard between buzzers if the switch is thrown to B in each instrument and they are in good order. 85. Repeating coils.—Repeating coils are designed to with¬ stand moisture and a certain amount of rough handling. They are subject to failure, due to broken connections and corroded or dirty terminals. Repeating coils should be inspected before installation, for broken or loose connections outside of the metal cover. During the inspection loose or broken connections should be resoldered and corroded or dirty terminals should be thoroughly cleaned and brightened with sandpaper or emery cloth. Repeating coils should be completely tested as follows: a. Clean the terminals and replace loose connections outside of the metal cover. b. Connect two repeating coils by short pieces of wire of equal length, as described in paragraph 52 c, for simplexing. Then connect four serviceable telephones to the two coils, one pair of telephones to the metallic circuit and one pair of tele¬ phones to the ground return circuit, as described in paragraph 52 c. The test consists in ringing and talking over each cir¬ cuit. If unable to ring or talk over either circuit, test each of the jumpers between each binding post and the corresponding coil terminal, both for continuity and for cross with any other jumper. If the jumpers are clear of trouble, the trouble is probably in the coil windings which are inside the iron case. c. If the first test shows that both circuits are clear, ring and talk over each circuit while listening over the other circuit. If the ringing or talking over one circuit can be heard over the other circuit, the coil is defective. Do not remove the iron case. A defective repeating coil should be sent to a signal depot for repair. 86. Transportation of wire equipment in the field. — a. Operating equipment .—Operating equipment is comparatively delicate and its serviceability is governed to a great extent by care in methods of packing it for transportation. Operating equipment is packed and loaded in such manner as to protect it from— (1) Dust and dirt. (2) Weather. (3) Shocks of the road. (4) Injury from other articles loaded in the same vehicle. 110 BASIC FIELD MANUAL b. Telephones are packed in the BC-5 pack chests when pro¬ vided. The EE-4-A telephones are packed with the hook switch turned in, crank handles turned up so as to be flush with the case, hand set cord neatly wound around hand set, and hand set inserted in the case with the receiver end down, the lid closed and latched and the carrying strap tightly buckled and coiled on top of the lid. The EE-5 telephones are packed in the same manner except that the crank is removed from the generator shaft and placed under the spring catch provided on the panel of the telephone. Care must be exercised in winding the cord around the hand set to see that it does not press on the button switch on the side of the *hand set. Certain types of wire-laying vehicles have built-in compartments for transport¬ ing telephones. Telephones transported in such compartments should be packed in a manner similar to that described above. c. Switchboards. —Monocord switchboards with cable and switchboard terminal strip attached are packed in a BC-5 pack chest separate from telephones. Before placing in the pack chest, the switchboards are placed in their carrying cases wit^i shutters locked and cable neatly coiled. The monocord switchboard sometimes is packed for transportation in compart ments provided for the purpose in certain tj^pes of vehicles; when so packed the same precautions are taken as when packing in the pack chest. d. Repeating coils, terminal strips, spare batteries, and spare parts are carried in the pack chests provided, packed in such manner as to prevent injury to themselves or other equipment in the same chest. e. Service buzzers and buzzer phones are carried in cases of more sturdy construction than those used for other operating equipment, and they may be packed outside of special pack chests without danger of injury. However, where pack chests are available, it is desirable to use them for packing this equip¬ ment as a more compact and more easily handled load results. j. Wire. —The principal precaution necessary in transporting wire is that the metal drums or commercial spools be not dropped from vehicles or handled in such a manner as to injure or bend them and thereby make difficult their refilling and use. CHAPTER 3 Section I. II. III. IV. V. VI. VII. VIII. IX. X. XI. XII. RADIO General__ _ Operating regulations_ The call up and answer_ Station records_1L _:_ Tactical radio nets_ Message forms and classification Methods of sending messages_ Message handling____ Artillery-fire control___ Procedure signals___ Dry batteries _ __1 . Storage batteries__ Paragraphs 87- 93 94-103 104-109 110-112 113-118 119-122 123-126 127-138 139 140-141 142-143 144^158 Section I GENERAL 87. Employment. — a. Radio is used as a means of communi¬ cation between all combat units down to and including battalions and individual airplanes. b. Radiotelegraphy is the normal means of radio communica¬ tion. There are at present certain limited uses for the radio¬ telephone, such as between airplanes and between ground and airplanes. c. Radio communication within a tactical unit on the march is established at such prearranged times or places as tnay be necessary. 88. Powers and limitations. — a. The range and quality of radio communication are independent of conditions of roads and traffic and are only slightly affected by the nature of the inter¬ vening terrain. b. Radio communication can be used between rapidly moving units when distances are so great and movement so continuous that wire and messenger communication can not be maintained. Under these conditions arrangements may be made for radio communication between distant stations at fixed hours. Ill 112 BASIC FIELD MANUAL c. Radio communication is not secret. This disadvantage necessitates the habitual use of cryptograms in transmitting messages. d. The approximate number, types, and locations of our radio stations can be determined by hostile goniometric stations. From this information and a knowledge of our radio organiza¬ tion, the enemy can estimate the organization and distribution of our forces. This disadvantage can be minimized by— (1) Curtailing the use of radio during a period of concentration or stabilization; or (2) Establishing dummy stations. e. Hostile stations can interfere deliberately with our radio communication. Such a practice, however, ordinarily interferes with-hostile radio stations as much as with our own and is there¬ fore not generally employed. /. Serious interference, called “static,” may result from cer¬ tain atmospheric conditions. 89. Radio nets. —In order that radio communication may follow the proper channels of tactical command, the radio station of a superior unit and the radio stations of the next sub¬ ordinate units are grouped into one radio net. Each net is designated by the name of the superior unit. The division net includes the division headquarters station, the brigade head¬ quarters stations, and the stations at the headquarters of auxiliary or attached troops under direct division control. The brigade net includes the brigade headquarters station and the regimental headquarters stations. The regimental net includes the regi¬ mental and battalion headquarters stations and the stations of units attached to or supporting the regiment. 90. Assignment of frequencies. —In order to prevent inter¬ ference between stations operating in a restricted area and to coordinate all radio activities within larger units, each radio net is assigned certain definite frequencies, wave lengths, or tuner settings on which to operate. These frequencies are normally allotted by army headquarters and assigned to units through corps and division headquarters. The use of any frequency not assigned by higher headquarters is prohibited. 91. Net control stations. —The operation of radio nets must conform to tactical conditions. Stations in these nets advance and retire with their units. In emergencies, messages of vital military importance must be given the right of way. The varying tactical situation requires net discipline and central BASIC FIELD MANUAL 113 control, in order that the radio net may serve promptly the will of the commander. To insure this control a net control station (NCS) is designated for each net. The NCS is normally the station of the superior tactical unit represented in the net for the reason that the superior commander has control over the radio communication of his subordinate units. The NCS is charged with the clearing of message traffic within the net, with dispatching internet traffic expeditiously, and with maintaining operating discipline within the net. Its orders on such matters will be obeyed by the other stations in the net. 92. Location of stations. —The following cohsiderations are important in the location of radio stations: a. The station should be quiet, dry, and protected from the enemy fire. Incoming radio signals are sometimes very faint, and noise and confusion make it difficult for the operator to copy them. b. Stations should not be placed in the immediate vicinity of electric-light plants, telephone exchanges, or wires carrying alternating current. Interference may also occur when two radio stations are placed too close to each other. 93. Special uses. — a. Radio is used in the military service for the following special purposes: (1) Reception only. (a) Goniometric location of enemy radio stations. ( b ) Goniometric location of enemy airplanes. (c) Interception of hostile radio messages. ( d ) Interception of friendly radio messages (supervision). (2) Transmission and reception. (а) Meteorological information. (б) Time signals. (c) Press reports. b. The goniometric and intercept services and the meteorolog¬ ical service are operated and maintained by the signal services of the higher units, usually the army. c. At army headquarters, for purposes of supervision, one or more radio sets are usually assigned the special mission of inter¬ cepting our own radio traffic within the different nets. These sets are adjusted to the frequency of the net or station to be supervised and copy all matter transmitted. The sending of messages in clear, or any other violation of regulations, is reported to the proper authority for correction. 114 BASIC FIELD MANUAL d. Official time signals are broadcast at stated times by a set located in the rear area. Designated field radio stations copy these signals in order that timepieces may be synchronized throughout the command. Time signals may also be sent by wire telegraph. e. At army and corps headquarters a radio set is assigned the duty of copying press reports and summaries which are broadcast by radio stations in the rear area. A set at division headquarters may also be assigned this duty when it is available. At head¬ quarters where no special set has been assigned this duty the sets designated for other purposes will not ordinarily be permitted to copy press, since, while they are being used for this purpose, they may not hear stations in their own radio net that wish to communicate with them. /. * Meteorological information is normally distributed by radio at fixed hours to units concerned. Section II OPERATING REGULATIONS 94. Introductory remarks.— a. These regulations are based on the Joint Army and Navy Radio Telegraph Procedure ap¬ proved by the Secretaries of War and Navy August 16, 1928, and contain the rules governing radio communication in the tactical nets of the Army. Details for intercommunication by radio between the Army, Navy, and Marine Corps will be made by the senior officers of these services in the area concerned. b. Strict compliance with the regulations insures the accurate reception and delivery of radio messages with a minimum of transmission. Every operator must understand the correct pro¬ cedure for use in any particular case. Deviation from the regu¬ lations will cause confusion in the mind of the receiving operator and will not only retard communication but in many cases will result in serious errors. _ 95. The international signal of distress (SOS). —The subparagraphs below are quoted from the general and supple¬ mentary regulations agreed to at the International Radiotele¬ graph Conference of Washington, 1927. a. “The distress signal shall consist of the group . . -- . . . which indicates that the ship, aircraft, or other mobile station sending it, is threatened by grave and immediate danger, and requests immediate assistance. BASIC FIELD MANUAL 115 b. /‘The distress call shall consist of the distress signal sent three times, followed by the word DE and the call sign of the mobile station in distress, sent three times. This call has abso¬ lute priority over all other transmissions. All mobile or land stations hearing it must immediately close all transmission capable of interfering with the distress calls or messages and must listen on the wave used for the distress call. This call must not be addressed to a particular station. The same rules apply to the radiotelephone distress call which consists of the spoken expres¬ sion MAYDAY (corresponding to the French pronunciation of the expression ‘ M ’Aider/ (help me) ).” c. “ When distress communications are ended and silence is no longer necessary, the station which has controlled these communi¬ cations will send a message on the distress wave addressed CQ, indicating that the distress communications are ended.” 96. Codes and ciphers.—Several types of codes and ciphers are used for cryptographing messages. A partial list of the various message codes and ciphers with their identification groups and the number of characters comprising each code group follows: Number of Name of code or cipher and code indicator: per group The War Department Telegraph Code (WTC)_ 5 The Army Field Code (AFC, followed by a number) 5 The Division Field Code (DFC. followed by a num¬ ber) _ 4 The Fire-Control Code (FCC, followed bj^ a num¬ ber)_ 2 The Air-Ground Liaison Code (AGC, followed by a number)_ 2 The Radio Service Code (RAD, followed by a num¬ ber)__ 3 The Meteorological Code (M, followed by two letters)_____ 4, 5, 6, or 7 ^Cylindrical Cipher Device, M-94 (CD)___ 5 97. Transmitting rules.— a. An operator will listen on the transmitting frequency assigned his station before making any call or other transmission. If there are other stations working on the frequency he will not interrupt communication unless such interruption is warranted by the class of his traffic. (See par. 122 b .) An operator must not cause interference that will prevent 116 BASIC FIELD MANUAL other operators from handling traffic if there is any possible way to avoid it. b. All transmissions must be as short and concise as possible. No superfluous calls or signals of any kind will be sent. An operator may test his transmitting set before the first trans¬ mission by sending a few “ V's” and then signing his own station call. c. Messages must be sent at a speed which will allow the stations addressed to receive them at the first transmission. Special care must be used when communicating with stations at which inexperienced operators are likely to be on watch. In sending a message to more than one station at a single trans¬ mission a speed of 16 words per minute should never be exceeded. d. Particular care is necessary that all call signs are made slowly and distinctly. 98. Procedure signals. — a. Certain nonsecret, arbitrary signals known as procedure signals have been adopted to assist operators in handling traffic in the shortest possible time. They must be kept posted or otherwise available in some convenient form near the operator. b. Procedure signals are never under any circumstances to be mixed with groups from other codes, or with cipher groups, in a transmission. 99. Transmissions. — a. A radio station will transmit only those messages authorized by competent authority. All trans¬ missions and messages handled will be considered as official. b. At times there is need for certain inquiries, instructions, and information in connection with the handling of radio traffic. In general, this need is adequately met by the system of procedure signals. When procedure signals can not be used a message will be employed. The exchange of transmissions in other than authorized form is prohibited. c. The chief operator of a radio station has full authority to authorize the transmission of messages relating to the communi¬ cation service. Such messages will be signed with the call letters of the station of origin, and will be in an approved code, normally the Radio Service Code. d. Every operator will read through the text of each message filed to ascertain that each word or the individual letters of each code group are clear and unmistakable. If there is any doubt about any of the words or letters he will have them verified. BASIC FIELD MANUAL 117 100. Time entries and the “ radio day.” —When stations in the same net are in different time zones, the following will hold: a. Time entries on the station records will be made in the time of the zone in which the station is located. b. Transmissions involving the specifying of time (time broadcasts, transmissions as to the time a station will call another station or return to a net, etc.) will likewise use the time of the zone in which the station is located. c. The “radio day”—i. e., the 24-hour period covered by a I complete set of station records—will commence at midnight of the time zone in which the station in control of the net is located, and end at the following midnight of the same zone. Station records (including number sheets when used) of all stations in 1 the net will be opened and closed in accordance with the above- mentioned rule. 101. Cooperation with the message center. — a. There must be close cooperation between a radio station and its message center. The station will keep the message center informed at all times of the stations actually present in the net and the probable time of return of any absent stations. b. Message centers keep track of the average delay time on messages, and usually mark them with an expression such as, “ Notify this message center if unable to transmit before-.” If from the state of traffic or other conditions operators can deter¬ mine that a message will be delayed beyond the allowed time, they will at once notify the message center. The message center has authority to change the means by which the messsage is to be transmitted. The radio station will always notify the message center when it has been unable to send messages within a reasonable time or the delay time prescribed. 102. Reception. —a. All received messages are copied at the radio station in duplicate. Code messages will be printed or will be copied on the typewriter. Printed characters will be , formed in accordance with standard practice and copied, five code words to the line. In using the typewriter, 5 or 10 code words will constitute a line. b. The originals of all messages received at a radio station and addressed to that station will be turned over to the message | center at once unless the message is in the Radio Service Code or in the abbreviated form. If the message is in the Radio Service Code, it will at once be decryptographed within the radio station. 118 BASIC FIELD MANUAL If it does not concern the radio service, it will immediately be turned over to the message center. If the message is in the abbreviated form, it will be turned over to the responsible officer by the quickest method available. If the message is in a code other than the Radio Service Code, it must be decryptographed by the cryptographer. c. The originals of all messages received for relay by radio will be put at the bottom of the file of other messages of the same class on hand and awaiting transmission. If the message is for a radio station in a net w liich has a station at the headquarters served by the receiving station, the message will be passed to the linking station in the same manner that a message is sent to the message center. d. The originals of all messages received for relay, which can not be relayed by radio, will be turned over to the message center at once. 103. Operator’s sign.—Each operator will be identified by a personal sign of one or two letters. No two operators in the same station will use the same sign. The personal sign of an operator will never be transmitted but will be used only in con¬ nection with the keeping of station records. Section III THE CALL UP AND ANSWER 104. Calls.—A call consists of the call sign(s) of the called station (s) followed by the procedure signal V and the call sign of the calling station. W hen it is desired to communicate with more than one station at the same time there are provided the following three methods of calling: a. Collective call. A collective call is one containing some prearranged call sign definitely calling two or more stations without the use of their individual call signs. A collective call may also be used in sending to more than one station a trans¬ mission consisting only of procedure signals. Under this classi¬ fication are included the three general calls ZLV, USA, and USN. (1) The general call ZLV is used principally when press, meteorological, and other data are broadcast from some central station to all stations within hearing. Stations listening are to copy but not answer. Such transmissions terminate with VA and if receipt or answer regarding reception is desired, it is obtained by an individual call up. BASIC FIELD MANUAL 119 (2) The general calls USA and USN are for all Army, Navy, and Marine Corps stations. The appropriate general call will be used to establish communication in case the call sign of the station with which communication is desired is not known. Example: An Army station, BA, desires to communicate with any Navy or Marine Corps station within range. BA would send— USN USN USN V BA BA BA K b. Net call .—In addition to assigning call signs to individual stations in a net there is also provided a call sign for the whole net. This is known as the net call. Such a call sign is used to call all of the stations in a net at one time. c. Multiple call .—A multiple call is one containing the individ¬ ual call signs of two or more called stations. It must always be used in transmitting a message (as distinguished from transmis¬ sions consisting of procedure signals only) to more than one station in a single transmission. It may also be used in trans¬ mitting procedure signals to more than one station. 105. Call up.— a. A call up consists of a call, followed by the ending signal K. Procedure signals, if necessary, may follow the call in order to convey certain information to the called station (s). In this case either K or VA completes the call up, depending upon whether or not the calling operator desires an answer. b. When the calling station has not recently been in communi¬ cation with the called station (s), or when it is known that the stations are not working well together, all call signs in a call up will be made three times, and any informatory transmission pre¬ ceding the K or VA will be made twice. Example 1 .—DB has routine messages for DA and communi¬ cation with that station is not known to be good. He transmits— DA DA DA V DB DB DB K Example 2 .—DB has a priority message for DA. He transmits— DA DA DA V DB DB DB P P K Example 3 .—Same conditions as in Example 2 except that DB, having made some adjustments in his transmitter since he was last in communication with DA, also desires to know how DA is receiving him. 120 BASIC FIELD MANUAL He transmits— DA DA DA V DB DB DB P P ZJF ZJF K c. In calling up a single station, when the calling station knows that it is in easy touch with the called station, call signs and pro¬ cedure signals will be sent once only. In certain cases, such as successive transmissions between the same two stations, when there can be no confusion as to the identity of the stations, the call may be omitted after the initial transmission. Example .—DA and DB have been in communication. DA has told DB that his signals are good and has transmitted a message to him. DB wishes to call DA and receipt for the mes¬ sage. He may transmit either— DA V DB R NR3 K (or VA) or R NR3 K (or VA) 106. Failure of called station to answer. —When a station fails to answer a call up, the following rules will be observed: a. The call up will be repeated once immediately. If the second call up is not answered the transmitting station will wait at least two minutes before repeating the call up. Thereafter he will call only at 5-minute intervals unless he has an O or P mes¬ sage, in which case no restriction is placed upon the repetition of the call. b. If, within a reasonable time, or the delay time specified by the message center, the calling operatoi is unable to get in touch with the called station, he will return the message to the message center with the proper notations made thereon, “Unable to raise station.” When convenient this information may be given verbally. c. If a message is so returned to the message center bearing such a notation, the message center may— (1) Send the message by other means. (2) Direct the operator to continue calling for a specified time. (3) Direct the operator to send his message without prelim¬ inary call up and answer. In this case the operator would terminate his transmission with K. If he fails to receive a receipt from the called station he may request it not oftener than once every five minutes. If he fails to receive such receipt BASIC FIELD MANUAL 121 within a reasonable time, or the delay time specified by the message center, he will so notify the message center. This method is provided so that a station whose transmitter is out of operation but whose receiver is still operating will be able to receive all messages intended for it even though it can not receipt for them by radio. All operators should therefore continue to listen in even though their transmitters are out. 107. Collective or multiple call up.—In a collective or multiple call up, when the calling station knows that it is in easy touch with the called stations, the call sign(s) of the called stations will be made twice and the remainder of the trans¬ mission once only. The exception to this is in the case of sending a message without preliminary call up and answer. (See par. 123a (3).) 108. Answering. —a. An answer to a call up is similar to the call up and follows the rules given in paragraph 105. For reporting signal strength in an answer, see paragraph 109. b. A general call up terminating in “K” calls for an answer from any nonsilent station hearing the call up, unless the included informatory transmission specifies otherwise. Example .—DA wishes to establish radio communication with any Army station. He transmits— USA USA USA V DA DA DA K Any nonsilent Army station hearing the above call up will answer. c. A net call up requiring an answer is answered by the called stations in the alphabetical order of their call signs. d. A multiple call up requiring an answer is answered in the order in which the stations were called. If a called station fails to answer in its turn, the next station in the order of an¬ swering, after waiting 15 seconds, will answer and the delinquent station will not answer until all other stations have finished. If the delinquent station still fails to answer, the calling station will call it individually. Example 1. —DA, DB, DC, and DF constitute a net wiiose call sign is DAB. DA, the net control station, wishes to tell all stations to “close station .” All stations have been in easy touch with one another. DA transmits— DAB DAB V DA ZZX K DB answers— DA V DB R VA 122 BASIC FIELD MANUAL DC fails to answer. After 15 seconds DF answers— DA V DF R VA DC still failing to answer, DA transmits— DC DC DC V DA DA DA ZZX ZZX K and DC then answers— DA V DC R VA Example 2 .—Under the same conditions as in Example 1, DA wishes a report of traffic from DB and DF only. DA transmits— DF DF DB DB V DA ZAQ K DF answers— DA V DF ZAR FOUR DB VA DB answers— DA V DB ZBJ VA 109. Indicating strength of signals or interference.— a . The strength of signals or interference will normally be reported by use of the table of signal strength, which is as follows: Strength: 1 ___ 2 ___ 3___ 4_:'„ 5_ Meaning Very weak, hardly audible. Moderately weak. Medium strength. Moderately strong. Strong. b. Readability of signals is indicated after the procedure signal R, by means of the table below: (1) Unreadable. (2) Poor but readable; plain language twice; code unreadable. (3) Fair; readable; plain language once, slowly; code twice. (4) Good; readable; plain language or code once. (5) Perfectly readable. c. The procedure signals S or R followed by a number from the table of signal strength or table of readability will be used to indicate the strength or readability of-the received signal. BASIC FIELD MANUAL 123 Example 1. —DA, having called DB, the latter would report DA’s signal strength as follows: DA DA DA V DB DB DB S4 S4 K Example 2. —DA, in receipting for a message to DB, wishes to report a material change of signal strength from DB. He might transmit as follows: DB V DA R NR4 S2 VA Example 8. —DA, in answering DB, wants to inform him that his signals are moderately strong and readability fair: DB V DA S4 R3 K d. The “strength of signals” will be indicated under the fol¬ lowing conditions: (1) In answer to an original call up or message when commu¬ nication is first established. (2) In the first transmission the original calling station makes after receiving an answer to its original call up. (3) If the strength of the received signal has changed mate¬ rially since establishing communication. (4) In answer to a request made by a procedure signal as to the strength of signals. (5) Whenever a station desires another station to increase or decrease signal strength. e. The transmitting station will make every effort to maintain a signal strength of “4” for the receiving station. When this is impossible great care must be exercised in transmitting messages. The sending must be heavy so the dots will carry through and the spacing must be good. It is also advisable un der t hese conditions to follow extremely difficult groups with I MI and then repeat the groups. When the signals are reported as strength “2” or below, all groups will be sent double unless the receiving station requests otherwise. /. A receiving station will always request that each group or each message be sent two or more times when the signals are hard to copy due to static, radio interference, swinging, fading, or any other cause. While the repeating of groups or messages is not to be encouraged, traffic can, in many cases, be handled more quickly this way than by sending single and causing the receiving operator to ask for numerous, repetitions. 1143 °— 31—5 124 BASIC FIELD MANUAL g. The strength of interfering radio signals and static may be indicated in a like manner by using W and X, respectively. Example. —DA, having called DB, the latter wishes to report DA’s signals as “moderately weak” and radio interference as “medium strength” and static as “strong.” DB might transmit— DA DA DAV DB DB DB S2 S2 W3 W3 X5 X5 K h. When radio interference is coming from a known station the call letters of the station may be sent after the “W” and a number from the table of signal strength. Example. —DA, having called DB, the latter reports DA’s sig¬ nals “moderately strong” and radio interference from BX > as: DA DA DA V DB DB DB Si S4 W4 W4 BX BX K Section IV STATION RECORDS 110. Operator’s number sheet.— a. In regimental and brigade nets, messages are normally identified, both upon station records and during transmission, by the serial number assigned to the message by the message center. This method is particu¬ larly suited to stations whose operation is intermittent, and whose employment is such as to limit the use of records. Should conditions warrant, the officer responsible for the operation of any one of the above-mentioned nets may direct the employment of station serial numbers as prescribed below. b. In nets above the brigade, station serial numbers are used on all normal form messages (see par. 119) to assist each station in ascertaining that all such messages, both incoming and out¬ going, have been received. They will be used as follows: (1) By each station, using a separate “transmitted” series and a. separate “received” series for each station communicated with during a “radio day,” The first normal form message sent to each station after midnight will be numbered “1.” Similarly the first normal form message received from each station after midnight will also be numbered “1.” Succeeding messages are numbered consecutively until the following midnight v> hen a new transmitted series and a new received series commence for each station communicated with. BASIC FIELD MANUAL 125 (2) Messages sent by means of a collective call or in abbreviated form and transmissions consisting of procedure signals will not be given a serial number by the transmitting station. (3) A message sent by means of a multiple call will be given the proper serial number for each station called by the transmit¬ ting station. (4) The station serial number applies only between the trans¬ mitting station and the station to which the message is trans¬ mitted. If the message is to be relayed by radio, a new station serial number is assigned to it by the relaying station. c. A record of the consecutive station serial numbers with each other station will be kept on an operator’s number sheet in the following manner: (1) On the completion of the transmission or reception of a normal form message (s), each key operator concerned will draw a line through the number(s) of the message(s) sent (or received), on the number sheet, in the column (s) assigned to the other station (s) involved. (2) When an operator is relieved he v/ill affix his sign to the number sheet to indicate the blocks of numbers he has handled. This may be done by any convenient method such as inclosing these numbers by a pencil line and affixing his sign in the space in the margin. ra ,, f { 126 BASIC FIELD MANUAL (3) The following form indicates a satisfactory number sheet for recording station to station serial numbers: SIGNAL CORPS, UNITED STATES ARMY Operator's number sheet Station_ Date_, 19__ Sent Reed. Sent Reed. Sent Reed. Sent Reed. Sent Reed. 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 V 3 3 3 3 3 3 • 3 3 3 3 4 4 4 4 4 4 4 4 4 4 5 5 5 5 5 5 5 5 5 5 6 6 6 6 6 6 6 6 6 6 7 7 7 7 7 7 7 7 7 7 8 8 8 8 8 8 8 8 8 8 9 9 9 9 9 9 9 9 9 9 10 10 10 10 10 10 10 10 10 10 11 11 11 11 11 11 11 11 11 11 12 12 12 12 12 12 12 12 12 12 13 13 13 13 13 l 13 13 13 13 13 14 14 14" 14 14 14 14 14 14 14 15 15 15 15 15 15 15 15 15 15 16 16 16 16 16 16 16 16 16 16 17 17 17 17 17 17 17 17 17 17 18 18 18 18 18 18 18 18 18 18 19 19 19 19 19 19 19 19 19 19 20 2C 20 20 20 20 . 20 20 20 20 d. In case of irregularity in the number sheet and the files of transmitted and received messages, the chief operators of the stations concerned will be notified at once and every reasonable BASIC FIELD MANUAL 127 effort made by the stations and their message centers to locate the discrepancy. In all cases the following rules will be observed: (1) If the discrepancy can not be located in the time available, a new series of numbers will be started between the stations con¬ cerned, commencing with the first number which both stations agree is free. Explanatory notations will be made on the number sheets covering the occurrence. (2) If two messages have been assigned the same number, the one bearing the more recent filing time will be assigned the half number above the number concerned bj^ the station (s) affected. (3) If a number has been omitted the word “blank’’ will be written opposite it by the station (s) affected. e. Station serial numbers should be checked by comparing numbers with each other station worked before closing station, or as soon as possible after midnight. If any discrepancy in sta¬ tion serial numbers is found in the comparison, and if the error can not be corrected by procedure signals, messages will be sent making the necessary corrections. 111. The station log. — a. A radio station log shows, in conjunction with the files of transmitted and received messages, a complete and continuous record of all transmissions and oper¬ ating conditions occurring during a “radio day” of which the operators on duty have knowledge. Such a log will be kept as follows: (1) If there are two operators on duty at a station, the senior operator, known as the key operator, will be responsible for the transmission and reception of messages and the keeping of num¬ ber sheets. The junior operator, knowm as the log operator, will keep the station log and enter thereon all transmissions of wilich he has knowledge, except messages transmitted by his own station. (2) If only one operator is on duty, he will perform the duties of the key operator and in addition will keep the station log as prescribed for the log operator, except that messages in¬ tended for his station will not be copied in the log. The follow¬ ing form is a satisfactory example of station log: 128 BASIC FIELD MANUAL STATION LOG Date_19_ _ Net_ Sheet No_ Station call_ Net call_ Station opened_M _Senior operator _Junior operator Time To From Traffic b. The following rules concerning entries made on the station log will be observed by all operators: (1) In every case where message transmissions are not copied in the log an explanatory entry, such as “Sent NR3 DB” (trans¬ mitted our message No. 3 to station DB), or “ Red NR 6 to 9DF” (received messages Nos. 6 to 9, inclusive, from DF), will be made. (2) All call signs, calls, call ups, answers, transmissions, or messages sent more than once need be copied but once. In case of excessive or unnecessary transmissions, repetitions, or repeat backs, sufficient explanatory notation should be made to render the log record complete and understandable. (3) An entry will be made in the log at least once every five minutes during the time a station is in operation. If there is no traffic being handled in the net or on the frequency guarded, an entry to that effect will be made. (4) The time associated with each entry will be entered on the log in a separate column. (5) In addition to the entries prescribed in connection with actual transmissions, the heading of each log sheet will be com¬ pleted and an entry will be made covering any unusual occur¬ rence or any violation of procedure rules. (6) When the operator in charge of the log is relieved he will make as his last entry on the log a statement, such as: “631 P-Cpl. Jones relieved by Sgt. Smith.” Each operator will sign his name and grade on the next line below. BASIC FIELD MANUAL 129 c. Signal or communication officers will inspect the log sheets of all stations under their command and ascertain that the pre¬ ceding rules have been carried out and that logs are being kept in a neat and legible manner. From a study of a properly kept log sheet, violations of procedure rules and faults in net opera¬ tion can be located and the delay time on messages computed. This renders the log a particularly valuable aid in training. 112. Filing station records.—All copies of transmitted messages, the carbon copies of messages received, the station log, number sheets, and any other records connected with the operation of a station for a “radio day” will be placed together in a packet as soon as possible after the conclusion of such period and plainly marked with the date and a description of the contents. These records will be disposed of as prescribed by the unit signal or communication officer. Section V TACTICAL RADIO NETS 113. Radio nets.—a. Army radio stations are organized into radio nets for the purpose of facilitating the handling of traffic. Stations normally having the greatest amount of inter¬ communication are assigned to the same net. Definite rules for the handling of net and internet traffic and the maintenance of net discipline are provided. b. Tactical nets are made up of mobile, low-power radio sta¬ tions of tactical units in the field. Tactical nets are generally given a name indicative of the senior organization in the net that is, the GHQ net, the First Army net, the II Corps net, the 3d Division net, the 4th Field Artillery Brigade net, etc. c. Nets operate either on schedule or with a continuous watch. Nets operating on schedule handle traffic only at definite, pre¬ arranged times and in accordance with a prearranged schedule of intercommunication. Nets operating on continuous watch are prepared to handle traffic at any time; they maintain operators on duty at all stations in the net at all times. d. All stations in a tactical net normally operate on the same frequency. 114. Net control.— a. In every Army tactical net one of the stations is designated as the net control station abbreviated NCS. The NCS is charged with the clearing of traffic within the net, with dispatching internet traffic as quickly as possible, 130 BASIC FIELD MANUAL and with maintaining order within the net. Questions concern¬ ing traffic are referred to the NCS for decision. The authority of the NCS extends only to the operation of the net on the air, and is in no w r ay concerned with the interior administration of any station, nor with its tactical operation or movement. With¬ in its scope, however, the authority of the NCS is absolute, its decisions are final, and its orders will be strictly obeyed. These orders are generally transmitted in the form of procedure signals, or messages, but may be contained in written orders, circulars, or letters of instruction. _ b. The NCS controls transmission by means of HM, UO, AS, K, and other procedure signals. c. Duty as NCS is generally assigned to the station of the senior organization in the net, but may be assigned to any station in the net which can best fulfill the duties. All other stations in the net are knowm as secondary stations and are under the control of the NCS. 115. Types of nets. — a. An Army tactical radio net may be operated as— (1) A 'Tree net/’ in which case any station can communicate with any other station in the same net without first obtaining permission to do so from the NCS. (2) A “ directed net,” in which case no station, except the NCS, can communicate, except for the transmission of urgent messages, with any other station without first obtaining the permission of the NCS. Permission granted to a station to transmit one or more messages covers all communication neces¬ sary to complete the transmission of such messages. b. Nets ordinarily are operated free, but the NCS may change to directed net operation at any time if it is unable other¬ wise to maintain proper control. In a directed net, traffic moves more slowly than in a free net. A directed net should only be used when all other means of obtaining order have failed. Free net operation will be resumed in all cases as soon as the necessity for directed net operation has passed. c. Secondary stations will always inform the NCS when they know they will be unable to follow out their schedules, or unable to have their station on continuous watch at any time during which a continuous watch is to be maintained. If it is impossi¬ ble to notify the NCS by radio it will be done by some other means of communication with the least possible delay. BASIC FIELD MANUAL 131 116. Transmission in secret and in clear language.— Normally all messages transmitted in Army tactical nets will be cryptographed. When the tactical situation is such that time can not be spared for cryptographing and decryptographing, and when the information to be transmitted can not, if picked up by the enemy, be acted upon in time to influence the situa¬ tion, a commanding officer or his representative may order the transmission of a message in plain language, provided that he makes this authorization in writing over his signature. Crypto¬ graphing and decryptographing will normally be performed by a cryptographer who 4s provided with the proper eodes and cipher keys. Messages relating to the radio service may be crypto¬ graphed by the radio personnel. 117. Traffic in tactical nets. — a. Tactical nets must be pre¬ pared to assume the entire traffic load of their units at any time. For this reason close cooperation with the message center is essential. Tactical radio stations will be given a telephone con¬ nection whenever possible. A continuous check on outgoing messages by radio should be kept by the message center so that it may ascertain at any time those messages which are at the radio station awaiting transmission. h. In order to protect urgent traffic, no station in a tactical net save those concerned in a communication will transmit during the communication, nor for a period of 15 seconds after the completion of the series of transmission which make up the communication, except to transmit urgent traffic. Interruption will then only be made when certain that the communication being interrupted concerns traffic of a lower class. c. Urgent messages will be transmitted to the station of destination, or to a linking station, as soon as possible, under the restriction imposed in b above, without in any case obtaining permission from an NCS. If such traffic is for a station in another net, the operator will report back into his own net upon completion of his internet communication. 118. Establishing a tactical net. — a. Before going into the field, station call signs, net call signs, duties and frequencies will be assigned to the various stations and nets. b. Radio stations in tactical nets conform to the movements of the organizations served. As soon as a tactical radio station is set up and in operation at the desired location it will endeavor to report into the net of which it is a part. 132 BASIC FIELD MANUAL c. The first station set up will act as NCS and the second sta¬ tion as NC2 until the regularly appointed NCS reports into the net and takes control. The NCS will, when necessary, cause each new station reporting into the net to adjust its frequency until all stations can be heard on the same dial setting of the receiver of the NCS. The NCS may adjust its frequency in accordance with directions from one of the secondary stations until that station receives the NCS and all other stations in the net on the same dial setting. This adjustment of net frequency will be made when the third station reports into the net and each station reporting thereafter with an incorrect adjustment will be caused to adjust its frequency before it transmits any traffic. The NC2 takes over the duties of the NCS in case the NCS disappears from the net or leaves the net ■without giving other instructions. Example 1 .—Stations DA, DB, DC, and DF go into the field to establish a net. Station DA has been appointed the NCS. The net call sign is DAB and the net frequency 450 KC. As¬ sume that station DA is the first station set up. DA will first listen on 450 KC and if nothing is heard will transmit— DAB DAB DAB V DA DA DA ZZA ZZA U U K This indicates to any secondary station -who might in the meantime have set up and be listening that the NCS is in the net and that he has taken control thereof. None other than the regular NCS is permitted to use the signal U. If no answer is received, DA will continue to listen on the net frequency and will transmit as above once each five minutes until some station answers or reports into the net. The NCS transmits as follows once each five minutes thereafter until all stations have reported in, except that traffic will not be delayed for this purpose: DAB DAB DAB V DA DA DA U U VA Assume that DB is the next station set up. After listening on the net frequency and hearing no station, DB will transmit— DAB DAB DAB V DB DB DB ZZA ZZA K DA hears DB report in and answers him with a report of signal strength, the type of net and the call signs of the other stations, if any, in the net: DB DB DB V DA DA DA S4 S4 ZZF ZZF K BASIC FIELD MANUAL 133 DB has no traffic to send so answers with a report of signal strength, as— __ DA V DB S5 VA DA does not answer. DC is now set up and reports into the net. Assuming that he heard DB report in previously to DA, or upon hearing DA send the net call followed by U, he would send as follows: DA DA DA V DC DC DC ZZA ZZA K DA answers just as in the case of DB, except that he tells DC that DB is in the net. DC DC DC V DA DA DA S5 S5 ZZF ZZF ZZK ZZK DB DB K DC answers— _ DA V DC S4 VA Example 2. —If, in Example 1, DC’s signals did not come in at the same point on the receiver as DB’s did, DA would cause DC to adjust to the same point by the use of the proper procedure signal. DC reports into the net as in Example 1, and DA answers— DC DC DC V DA DA DA ZLG ZLG K DC decreases frequency slightly and reports again as— DA DA DA V DC DC DC S4 S4 ZZA ZZA K DC’s frequency is correct now and DA answers him as in Example 1. DB has been standing by listening to DA and DC. DA now calls DB and requests information as to his own frequency, thus: DB V DA ZLC K DB answers— DA V DB ZLF K DA adjusts his frequency and sends— DB DB DB V DA DA DA ZLC ZLC K Note.—DA must send all call signs three times, as in the original call, after any change in his transmitter. DA’s frequency is correct now and DB answers— DA V DB So VA 134 BASIC FIELD MANUAL The net is now established as a free net with the stations able to intercommunicate without change in the setting of the re¬ ceiver dials. d. The NCS, as soon as the net is established and he has taken over control, will designate as net control station No. 2 (NC2) a secondary station in the net. The NC2 will assume command of the net under orders from proper authority or in the event the NCS disappears from the net or leaves the net without giving other instructions. In this case the NC2 will immediately designate another secondary station as an NC3 to take command in case NC2 becomes silent. Example .—DA wants to appoint BD NC2. DA sends— DB Y DA ZFQ NC2 K DB answers— _ DA V DB R VA e. A secondary station will always inform the NCS when it leaves or enters the net unless it has an urgent message for a station in another met. In cases involving urgent messages a station may leave its own net'without informing the NCS. Example .—DC receives orders to move and knows the move will take two hours. DC sends to DA, the NCS: DA V DC ZZB TWO K DA answers— DC Y DA R VA When DC reports back into the net he will do so in the same manner as when the net was originally established. /. The NCS may change the type of net operation whenever necessary by sending out the net call followed by the appropriate procedure signal. Example .—DAB is the call sign of a net which has been operat¬ ing free and DA the NCS wishes to change to a direct net. DA sends— DAB DAB V DA ZZD K All stations in the net receipt for this in the alphabetical order of their call signs. DB answers— DA V DB R VA BASIC FIELD MANUAL 135 DA does not answer. DC next answers— DA V DC R VA DA does not answer. g. When necessary, an authorized station may silence a whole net, certain stations in a net, or all stations on a certain fre¬ quency, by use of the “silence” signal (HM). The silence signal is construed as a command and must be obeyed as such. Its use is confined to those stations in authority such as airplanes and net control stations. It will not be used until other less drastic methods of obtaining order have failed. It will be annulled as soon as the emergency has ceased to exist. Example 1. —DA, the NCS of a net whose call is DAB, wishes to silence the net. DA sends— DAB DAB V DA HM HM HM HM HM HM Hi VA All stations in the net stop transmitting and remain silent. They will not transmit again, except to send urgent traffic or to answer a call from the NCS, until the NCS indicates that silence is no longer necessary. To lift the silence, DA sends— DAB DAB VDAUOUOUOUOUOUOUOVA Example 2 .—DA wishes to silence one station, DB, in his net. DA sends— DB V DA Hi HM HM HM HM HM HM VA DB will remain silent but the other stations in the net are not affected. Example S .—DA wishes to lift silence from a certain station, DB, in the net but not from the whole net. DA sends— DBVDAUOUOOUUOUOUOUOVA Section VI MESSAGE FORMS AND CLASSIFICATION 119. Normal form of message. — a. The normal form of message is to be used for all messages except those broadcast after a collective call (see par. 104 a (1)), unless specific instruc- 136 BASIC FIELD MANUAL tions are given to the effect that the abbreviated form will be used. See paragraph 120 for authorized uses of the abbre¬ viated form. b. The subdivisions of the transmission of any message in the normal form appear below. Part Example When used Subpara¬ graph Call __ NA V BA _ Always m Number. . _ NR3_ U sually V 1 / (2) Operating instructions G (etc.)_ Special cases only (3) Class.— ... _ _ (0 or P)_. TTre'ent or nrinrifv (4) messages only. Check _ .. GR7 _ Usually (5) Break. . _ _ BT _ Always Text. _ The message in secret or do v u / m clear language. Time of origin _... 923A _ Usually (8) Ending signal _ AR (followed by K, B, Always \PJ (9) VA, etc.) (1) The call consists of the call sign(s) of the station (s) called (in alphabetical order), followed by V and the call sign of the station calling. (2) (a) Regimental and brigade nets transmit here, preceded by the procedure signal NR, the serial number given the message by the message center. In case no such number is given this group is omitted. (Jb) In nets employing the operator's number sheet and station serial numbers, a message transmitted to a single station carries here an identifying serial number preceded by the procedure signal NR. If a message to a number of stations is transmitted simultaneously by means of the multiple call, an identifying serial number for each called station, preceded by the call sign of the called station and the procedure signal NR, will be inserted in the order in which the stations are called. If a mes¬ sage to a number of stations is broadcast by means of a collective call, no entry will appear here. (3) Instructions to the station(s) called (F, G, etc.) appear here if necessary. (4) A procedure signal (O or P) designating the class appears here except in the case of a message of routine classification, which carries no symbol. BASIC FIELD MANUAL 137 (5) The actual number of groups, as counted by the message center and verified by the operator, preceded by the group(s) sign GR, appears here. Everything between the BT and AR is°counted. The writer’s number, code indicator, and time of origin are each counted as a group. . _ (6) The text is always preceded by the break signal B1 and followed by the end of message signal AR» (7) - In a cryptographed tactical message the text will normally include the writer’s number as the first group. The last group will normally be the time of origin if this is placed on the original message by the author. The code indicator may or may not be shown depending upon the amount of traffic in one code handled by the stations concerned. If used, it appears as the second group of the text. (8) The time of origin is transmitted as a group of four oi five characters, the last being A or P, to indicate AM or PM; thus 653A or 1057P. Note—I n intercommunication between Army and Navy units the time of origin will be expressed by the 24-hour clock method. Thus the two times shown above would read 0653 and 2257. (9) The “end of message” signal, AR, will always be used to terminate each message._If it is the last message to be sent, it will be followed by K, VA, or such other procedure signal as conveys the desires of the transmitting operator with respect to the transmission to follow. c. A tactical message in the normal form as copied by the receiving operator will ordinarily appear as below: DA V DB 5 P (g) 9 ( 13 Sept ) NR10 DFC4 PXQT RVMO TZXM BRTL OPTZ MABY 956A ( 1145 A) Note. —The characters inclosed in circles constitute the receiving operator s serv¬ ice. “D” is his personal sign, “13 Sept” the current date, and “1145A’ the time that the message was receipted for. The location of the personal sign and date within the messaee is so planned that they may be written during the reception of the signals Gli and BT, which are not copied, thus permitting the operator to copy consecutive messages without pause for servicing. If, due to the type of traffic, the above loca¬ tions prove inconvenient, local station regulations may prescribe that they be wiitten in any convenient place upon the message. 120. Abbreviated form message. — a. Local operating con¬ ditions and varying types of traffic may cause different items of 138 BASIC FIELD MANUAL the normal form message to be omitted. The greatest possible abbreviation of the message form is found in the direct trans¬ mission between command posts of urgent messages in clear. This type of message will frequently be handed direct to the radio station without passing through the message center. They are always of urgent nature and no class, station serial number, or check is transmitted. Example .—The commanding officer, 1st battalion (at RB), wishes to send an important message in clear to the regimental commander (at RA). After authorizing its transmission in clear, as prescribed in paragraph 116, he hands it to the operator and directs that he transmit it at once. RB sends— RA V RB BT Penetrated hostile main line of RESISTANCE AT FIVE A. M. AR K RA answers— RB V RA R VA The operator at RA causes the message to be delivered to his commanding officer by the quickest available means. b. The advantage gained by the use of radio for messages of this kind can not be overestimated. In many cases prearranged code words will convey all of the information that is necessary, and if commanding officers have knowledge of the brief messages that may be sent by the use of these words, the transmission of radio traffic of this nature is greatly expedited. c. Fire-control messages will generally be in a prearranged code for which no code indicator is necessary, and consequently their transmission will consist of the call; the preparatory com¬ mand sign IX when necessary; the break sign BT; the text and the end of the message sign AR. Call signs may be eliminated in the case of a continuous exchange of messages, such as occurs in artillery fire control, when there is little chance of confusion as to the identity of the stations. (See par. 139.) 121. Preparation of messages for transmission. —Mes¬ sages to be transmitted by radio will usually be filed at the mes¬ sage center. The message center places them in proper form for transmission, cryptographing if necessary. a. Before sending a message to the radio station for trans¬ mission, all data which are supplied by the message center for inclusion in the heading of the message will be written across the top of the face of the message. These may include— BASIC FIELD MANUAL 139 (1) Message center serial number. (2) The class of message. (3) Operating instructions. (4) The check. (5) The destination of the message indicated by the call sign(s) of station(s) of destination, as “send to NB.” If the message center can not supply the station call sign(s), it must supply the name of the organization (s) of destination in clear, as send to 1st F. A.” b. All other data, such as the maximum delay time, etc., will be inserted as a distinct and isolated group on the face of the message so as not to mar the text. c. Under exceptional circumstances, or when no message center is available, messages may be delivered direct to the radio station. In this case the operator will perform the duties ordinarily performed by the message center in supplying data for the heading of the message. If the message is to be sent in clear, it must be authorized by competent authority. 122. Classification of messages.— a. Messages are classi¬ fied to show the relative order in which they will be transmitted. This order is as follows: Class Classifying symbol Urgent- 0. Priority_ ^ >- Routine_None. b. The urgent classification is reserved for messages requiring the greatest speed of handling. Urgent messages will be sent immediately upon receipt, except when communication involv¬ ing another urgent message is being carried on. The urgent classification is used only in combat, or when combat is imminent (real or simulated), to indicate that the message following con¬ veys most urgent orders, information, or request pertaining to the combat. c. Priority messages are of such importance that they are given precedence over all routine messages waiting to be sent. Communication will not usually be interrupted to send a priority message. Messages giving orders for the immediate movement of troops, requesting authority for or reporting events affecting such movement, and messages requesting or controlling fire of any kind not immediately needed, are examples of the type of message which may be classed as priority in tactical nets. 140 BASIC FIELD MANUAL d. Routine messages require no special precedence. They are transmitted in the order in which they are received, or in such order as will clear the traffic in the shortest possible time. Section VII METHODS OF SENDING MESSAGES 123. Methods of radio communication.— a. Ordinary .— (1) The greater percentage of messages routed by radio will bear no operating instructions, such as the procedure signals F or G. The handling of those special cases in which these procedure signals occur will be discussed in b below. The fact should be kept in mind that there is only one normal form of radio message and only one ordinary method of transmitting it. In rare instances, tactical necessity may require a method or combination of methods of handling traffic not prescribed in detail herein. In such cases the signal or communication officer concerned will, through his knowledge of the situation and the regulations, prescribe the necessary details to meet the situation. (See b (3) below.) (2) Messages are normally handled either singly or in series of three or four, depending upon the number on file for each station. Ordinarily four transmissions are used; call up, answer, transmission of the message(s), and receipt for the message(s). A receipt must be obtained by the transmitting operator for every outgoing message before it can be considered as trans¬ mitted unless the operating instructions are such as to indicate that no receipt is necessary. Such cases as this latter will be shown in b below. Where the operator is communicating with another station about things pertaining to signal communica¬ tion, and is using Z signals, he may or may not request a receipt, depending upon the nature of the correspondence or his own desires in the matter. (3) When it is known that stations are in easy touch with each other the call up and answer, indicated in (2) above, may be eliminated. In this case the transmitting operator calls the station with which he desires to work, making all call signs three times, and then transmits his traffic. Example .—DB has a message for DA and by having com¬ municated with him previously knows that DA receives him very well. DB may dispense with the preliminary call up and answer, thus: BASIC FIELD MANUAL 141 DA DA DA V DB DB DB NR8 GR9 BT NR6 DFC4 XBQM TRMO YTSR BROT BMPL MLHI 926A AR K DA would receipt for the message: DB V DA R NR8 VA It is impossible to lay too much stress on transmitting messages in this manner and operators must be practiced constantly in reading messages so sent. If attention is given to this a prelim¬ inary call up will seldom be necessary and the result will be a considerable saving of time. b. Special. —(1) The importance of absolute accuracy in the handling of some messages may be such that the receiving operator should repeat the message back to the transmitting operator in order to check for errors. If this condition obtains, the procedure signal G, “ Repeat back,” will be included in the heading of the message. Example .—DB has been directed by his message center to have a priority message for DA repeated back. He transmits the message as follows: DA V DB NR5 G P GR7 BT NR10 DFC4 XPQR TMST RQMO LTHJ 1030P AR K DA repeats the message back as he received it and DB under¬ scores each word repeated back correctly. If the message waS received correctly in its entirety DB sends— DA V DB C VA Any incorrect portions are corrected by DB before giving DA the C signal. (2) When it is desired to send a message to a silent station whose location must not be disclosed to the enemy, the procedure signal F, “Do not answer,” will be placed in the heading in the space provided for operating instructions. In such messages each group will be sent twice and the transmission terminated with the “end of communication” signal VA. Example .—DB has a message for a silent station, DA. DB sends the message as follows: DA DA DA V DB DB DB NR3 NR3 F F P P GR6 GR6 BT BT NR2 NR2 DFC4 DFC4 QXTS QXTS RMIT RMIT SMRA SMRA ZTMO ZTMO AR AR VA VA 142 BASIC FIELD MANUAL DA does not answer. (3) It may be desired not only to prevent enemy goniometrie and intercept stations from locating a unit but also to keep from him any knowledge of its existence, and at the same time have one-way radio communication with such unit. This may be accomplished by sending the message to a third station, not con¬ cerned therewith, by the G method. The radio station of the concealed unit is required to copy and turn over to its message center all G messages transmitted on the net frequency. 124. Relaying messages.—By the use of the procedure sig¬ nal T, meaning “transmit to,” a message may be relayed through an intermediate station in reaching its destination. An example of the transmission used in relaying a single address tactical message follows: Example .—DF has a message for XB which he wants to relay through AC. AC V DF NR6 T XB Y DF GR5 BT NR8 DFC4 PQXT NUMR 915A AR K The transmission from AC to XB— XB V AC NR10 XB V DF GR5 BT NR8 DFC4 PQXT NUMR 915A AR K It will be noted that AC uses his own station to station serial number when retransmitting to XB and that the procedure signal T has been omitted. 125. Single transmission of the same message to several stations. —A message may be sent to two or more addresses at one transmission. (See par. 104c.) Example .—DA wishes to transmit a routine message addressed to DB, DC, and DF. He may either make a call up and obtain an answer from each station before transmitting the message, or he may send it without preliminary call up and answer as follows: DB DB DB DC DC DC DF DF DF V DA DA DA NR! DB _ NR4 DC NR5 DF GR10 BT NRii DFC4 XQPM DMTR XGRA _ MLOP ACFR NYMS VUXB I010A AR K Individual receipts are taken from each station in the order in which called. 143 BASIC FIELD MANUAL 126. Internet traffic. — a. Figure 82 is used in connection with examples of internet traffic and the handling of messages which must be relayed. It may be considered as representing a system of tactical nets. It should be noted that the D and R and the D and X nets are linked physically by having two stations at a common headquarters, while the A net is physically isolated. Consequently, while a message originating in the X net with destination in the R net could be handled either by relay through the D net or by direct communication—i. e., going to internet traffic—all traffic to or from the A net must be handled by inter¬ net methods. 6. A station may desire to leave its own net and go into another net in order to send traffic to stations in that net. In all such cases except for transmission of urgent messages the station must obtain permission from its own NCS to leave the net, stating with what station it is going to work, and must report to the NCS of the new net before transmitting any traffic in that net. A station will report back into its own net as soon as its business is finished in the outside net. In case the station does not know the cal] sign of the net or of the NCS, or the fre- 144 BASIC FIELD MANUAL quency to be used, it will ask for such information in its request to leave its own net. The only exception to the rule above is in the case of an urgent message, in which case a station will get the message through with a minimum of transmission; that is, a direct call up if possible. (See par. 117c.) Example 1 .—DC has a priority message for AC. DC trans¬ mits— _ _ DA V DC ZAR P AC K DA sends— _ DC Y DA ZZH VA DC changes to A net frequency and makes— ABC ABC ABC (or AB AB AB) V DC DC DC ZZA ZZA ZAR ZAR P P AC AC K AB answers— _ DC DC DC V AB AB AB S4 S4 ZZH ZZH VA DC sends— AC AC AC V CD DC DC P P K AC answers- DC DC DC V AC AC AC S4 S4 K DC then transmits his message and reports AC’s signal strength as S3. AC receipts for the message— DC V AC R NR1 VA DC reports back into the D net— DAB DAB DAB (or DA DA DA) V DC DC DC ZZA ZZA K DA answers— DC DC DC V DA DA DA S5 S5 VA Example 2 .—If in Example 1 DC had not known what fre¬ quency to go to or whom to call, its request to leave the net would have been— DA V DC ZBE P AC K and DA would have answered— DC V DA ZBF ABC (or AB) FOUR FIVE ZERO VA and the remainder of the communication would have been as in Example 1. BASIC FXEL-D MANUAL 145 Example 3. —(a) If DC has an urgent message for AC but does not know AC’s frequency, he requests this information of his own NCS, and then calls AC direct. ( b ) If DC has an urgent message for AC and knows AC’s frequency, he calls AC direct. Section Vltl MESSAGE HANDLING 127. Receipting for messages. — a. A receipt being one form of answer, the rules given in paragraph 105 apply to receipting as well as to answering. b. In receipting for a transmission consisting of procedure signals the received signal R is used without additional informa- tory data, except possibly a number from the table of readability, as provided in paragraph 109. c. In receipting for all messages identified by station serial numbers the received signal R followed by NR and the station serial number assigned by the transmitting operator will be used. When station serial numbers are used, receiving operators will always check the assigned station serial numbers and errors will be corrected with the transmitting station. Delivery of messages will not be delayed to make such corrections. d. When several messages have been received in a series the R is followed by NR and the station serial numbers of the first and last messages received in the transmission, separated by “to.” Any messages missed in the series or any repetitions desired must be obtained before receipting for the series; other¬ wise all messages in the series will be considered as receipted for. Example .—DA has sent a series of four messages to DC, messages Nos. 8 to 11, inclusive. After obtaining any necessary repetitions, DC sends— DA V DC R NR8 to NR11 VA DA does not answer. e. Receipting for net or multiple call ups and multiple call messages follows the rules laid down for answering in similar cases (par. 108 c and d), except that if a station fails to receipt for a multiple call message in its proper turn and fails to receipt after all other called stations have receipted, the transmitting operator will call the station individually and request such receipt. 146 BASIC FIELD MANUAL 128. Servicing of messages.— a. Every message is serviced by the transmitting operator and the receiving operator (s) upon the completion of its transmission. The transmission of a message requiring a receipt or a repeat back is not considered complete until such receipt or repeat back is received by the transmitting operator. b. The transmitting operator’s service may be written in any convenient space on the message. Many operators will perform this service with one hand while handling the key with the other. This service consists of— (1) The station serial number of the message, followed by the call sign of the called station. If it is a multiple call message, each station serial number and its associated call sign will be recorded. If the message carries no serial number the call sign(s) of the called stations will be recorded. (2) The personal sign of the transmitting operator. (3) The time of dispatch; that is, the time transmission of the message was completed. c. A receiving operator’s service consists of— (1) The personal sign of the receiving operator, which is entered on normal form messages immediately following the last station serial number, or the class if indicated, which appears in the heading. If no identifying serial number is used on col¬ lective call and abbreviated form messages it is inserted im¬ mediately after the group (GR) signal. (2) The time of receipt, TOR; that is, the time transmission of the message was completed. This is entered immediately below the end of the message. (See par. 119c.) 129. Errors in transmitting. — a. The error signal is used to correct a word or group which has been incorrectly trans¬ mitted. Should an operator in the course of a transmission make a word or group incorrectly, he will immediately make the error sign, then make the last word or group which was correctly trans¬ mitted and continue the transmission. The repeat sign, I MI, will never be used to correct a mistake made in transmission. Example .—DA makes an error in transmitting a message to DB and corrects himself as follows: DB V DA NR2 GR8 BT NR14 DFC4 KU EEEEEEEEEEEEEEE DFC4 KWSN OVRL XNTS RQAD KOGY 1050A AR K b. If, during the transmission of a message, it is discovered that a mistake has been made in transmission and it can not be BASIC FIELD MANUAL 147 corrected by the use of the error sign, the operator will make use of the procedure signal ZCR and will then start the message over again or proceed with other traffic, as the case might be. Example .—DA is transmitting a message to DB that should have been sent to DC. He discovers the error before he has completed the transmission and cancels the transmission as follows: DB V DA NR4 P GR10 BT NR5 II ZCR ZCR K DB answers— DA V DB R K DA answers DB and either tells him that he has no more messages for him or sends the other traffic he has for him. c. A separate message must be sent to cancel a message which has been completely transmitted and for which a receipt has been given. 130. Repetitions. — a. Repetitions are obtained by a receiv¬ ing station, befor e rec eipting for a message, by means of the procedure signals IMI, AA, AB, BN, and WA. b. Short messages will generally be repeated in their entirety when repetitions are asked for. c. Requests for a repetition of a portion of a message require— (1) Quoting the correctly received portions which stand next to, or on both sides of, the faulty portion, or (2) Indicating the groups by number which stand next to or on both sides of the faulty portion. d. It will be noted that c (1) above is applicable to all messages whether in clear or secret language, while (2) will more often be used in long cryptograph messages where a given group may appear more than once. It is obvious that in a long crypto- graphed message it is easier to find the seventieth group than group CAPJ. In all cases, the transmitting station will repeat the correctly received portion (s) quoted or indicated by the receiving station as well as the faulty portion on which the repeti¬ tion is requested. This gives a double check, as it shows beyond a doubt that it is the right portion being repeated, and that the faulty portion has been repeated in its entirety. e. The repetition of a message or portions of a message is to be made through once only, unless the sending station has been informed that reception is bad, in which case it may be repeated twice, or as many times as requested. 148 BASIC FIELD MANUAL Example 1— DA has transmitted a message to DB; DB will secure repetitions on this message in the manner shown in cases I to X. The message as transmitted by DB is as follows: DB V DA NR3 P GUI 3 BT /i\ /o\ ('Q'j (4) (5) (6) (7) NR6 DFC4 WXKZ RNTZ LOPY QRKS TNTU (8) (9) GO) (ID (12) (13) XART NQRK WFTS RXZY KOGY 620P AR K Example 2. —Any repetition that can possibly be asked for must fall within one or more of the following classes: Case I. —DB desires a repetition of the whole message. DB transmits— DA V DB ImI K DA answers— DB V DA NR3 P GR13 BT NR6 DFC4 WXKZ RNTZ LOPY QRKS TNTU XART NQRK WFTS RXZY KOGY 620P AR K Case II. —DB requests a repetition of the whole text. DB asks thus— DA V DB IMI AA BT K DA answers— DB V DA BT NRG DFC4 WXKZ RNTZ LOPY QRKS TNTU XART NQRK WFTS RXZY KOGY 620P AR K Case III. —DB has missed some portion of the heading. He must request a repetition of the whole heading. DB asks thus— DA V DB IMI AB BT K DA answers— DB V DA NR3 P GR13 BT K Case IV. —DB requests all after group No. 10. BASIC FIELD MANUAL 149 DB asks thus— DA V DB IMI AA GR10 K DA answers— DB y DA WFTS RXZY KOGY 620P AR K Case V. —DB requests all after the group WFTS. DB asks thus— DA y DB IMI AA WFTS K DA answers— DB V DA WFTS RXZY KOGY 620P AR K Case VI. —DB requests all before group No. 3. DB asks thus— DA V DB TM AB GR3 K DA answers— DB V DA NR3 P GR13 BT NR6 DFC4 WXKZ K * Case VII. —DB requests all before the group WXKZ. DB asks thus— DA V DB IMI AB WXKZ K DA answers— DB V DA NR3 P GR13 BT NRG DFC4 WXKZ K Case VIII. —DB requests the groups from No. 1 to No. 3. DB asks thus— DA V DB IMI BN BT II RNTZ K DA answers— DB V DA BT NR6 DFC4 WXKZ RNTZ K Case IX .—DB requests group No. 4. DB asks thus— DA V DB IMI BN GR3 II GR5 K 150 BASIC FIELD MANUAL DA answers— DB V DA WXKZ RNTZ LOPY K Case X. —DB requests groups Nos. 5 and 9. DB asks thus— DA V DB ImI WA GR4 II WA GR8 X DA answers— DB V DA RNTZ LOPY II XART NQRK K f. When requesting a repetition on one or more messages that have been sent in a series, the request must always indicate the serial number(s) of the message(s) involved. Example. —DA has sent DB four messages starting with NR3 and ending with NR6. (1) DB asks for repetition of message No. 5 as— DA V DB ImI NR5 X (2) DB asks for a repetition of groups 4 and 5 in message NR6, as— DA V DB IMI NR6 II BN GR3 II GR6 X 131. Verifications.— a. Verifications and repetitions are requested from the originating station by means of the procedure signal J. This means “ verify and repeat.” b. The term, “ verify and repeat,” means that the message center at the originating station must have the officer originating the message verify the phraseology of the message and correct any errors. If crvptographed, the message center will check the cryptographing. c. In using the J signal it is always necessary to designate the message to be verified, and for this purpose the station serial number will be used. Example. —DB has a message from DC and wants it verified and repeated. It is the first message DC sent DB. DB calls and asks DC to J his No. 1, as follows: DC V DB J NRI X DC answers— _ DB V DC R VA BASIC FIELD MANUAL 151 DC would have the message verified by the message center which would check it with the originating officer as soon as possible. When the verified message was received, DC would repeat it back to DB as follows: DB V DC ZCT NR1. II (The verified message) K d. It will sometimes happen that only a portion of a message is doubtful, and if it is a long normal form message it is not necessary to have the whole message verified. When only a portion of a message is to be asked for the same rules will be followed as in asking for repetitions, substituting J for IMI and using the other procedure signals as indicated. 132. Questioning accurate reception. —Before receipting for a message the receiving operator may desire to check his reception of a word, group, or portion of the message. In which case the “is this correct?” signal, I NT, will be used. Example 1 .—DA has transmitted a long message to DC, who has copied the correct number of groups but doubts the accuracy of the reception of the 26th group. DC sends— DA V DC INT GR26 XBOY K DA, finding that DC’s reception is correct, answers— DC V DA C K DC then receipts for the message. Example 2 .—In Example 1, if the 26th group had been XBGY instead of XBOY, DA would have answered— DC V DA GR26 XBGY K DC would have corrected his copy and receipted for the message. 133. Challenging the check. — a. When a message is received at a station and the check does not correspond with the number of groups in the text, the receiving operator will imme¬ diately challenge the check. To challenge the check of a message an operator calls and sends INT GR followed by the number indicating the check, as he counts it, and the signal K. b. When the check is challenged, the transmitting operator will immediately recount the number of groups in the text of the message; and, 152 BASIC FIELD MANUAL (1) If the check as sent by the receiving station is correct, he will answer by calling and sending the sign C followed by the ending signal K. Example. —DA sends a message to DB as follows: DB V DA NR3 P GR14 BT (1) (2) (3) (4) (5) (6) (7) NR6 DFC4 WXKZ RNTZ LOPY QRKS TNTU (8) (9) (10) (11) (12) (13) _ XART NQRK WFTS RXZY KOGY 620P AR K DB receives the whole message, counts the check and finds it should be GR13, and sends— DA V DB INT GR13 K DA recounts the text and answers— DB V DA C K DB answers— _ DA V DB R NR3 K (or VA) (2) If the check as sent by the receiving station is incorrect, he will answer by calling and sending the correct check. The transmitting operator will then u letter the text”; that is, send the initial letter of each group of the text, and follow with the ending signal K. To letter the text the first letter or figure of each word or group in the text is sent. Example. —DA sent the message in the example in (1) above with the correct check GR1.3 in the heading but DB fails to get one entire group, LOPY, and therefore counts the check as 12 instead of 13. DB sends— DA V DB INT GR12 K DA answers, giving the correct check as GR1,3 and • letters each group and word— DB V DA GR12 IINDWRLQTX N W R K 6 AR K DB checks the first letter or figure of each group as DA sends them and discovers that the group starting with L is missing. DB answers, requesting a repetition of the group starting with L— DA Y DB I MI WA GR4 K DA answers— DB V DA RNTZ LOPY K DB answers— _ DA V DB R NR3 K (or VA) BASIC FIELD MANUAL 153 134. Incomplete messages.—A message may be received at a radio station with several groups missing. If possible, the radio station secures a repeat and completes the message. If it is impossible to get the message completed within a reasonable time the operator must forward it and indicate the missing groups with the “blank” sign AAA. Fragments of messages are sometimes very valuable and radio operators must always forward them even though they may seem of little value. In all cases the completed version will be obtained and forwarded as soon as possible. Example .—DA has transmitted a message to DB as follows: _DB Y DA NR3 T DC V DA P GR1.0 BT NR16 DFC4 ERLU HTNK FBZL ACSM OVXG WRBY NPFT 930A AR K DB misses the groups underlined and due to lack of time, failure of communication, or other cause is unable to obtain a complete copy. The message would be retransmitted to DC as follows: DC Y DB ZCL II NR8 DC Y DA P GR10 BT NR16 DFC4 AAA AAA FBZL ACSM OVXG WRBY NPFT 930A AR K DC would copy the message in the same manner as sent by DB above, receipt for it, and before sending it to the message center would add a notation to the effect that the missing groups were so sent by DB. 135. Spacing. —The “space” signal, the letters II made separately, is used for the separation of procedure signals or other parts of the transmission when it is feared that confusion of signals might otherwise result. Space signals are not used to separate words or groups of the text; they are sometimes useful in the heading of a message or in messages consisting of procedure signals. (See examples, pars. 130 and 133.) 136. Repeating difficult portions. —In transmitting mes¬ sages in the clear or in the abbreviated form, difficult words or portions of the message may be repeated at once by the use of the “repeat” sign followed by a repetition of the difficult portion. This use of the repeat sign must not be confused with the use of the error sign in correcting a mistake. (Par. 129.) 154 BASIC FIELD MANUAL Example. —DA, in transmitting an abbreviated message to DC, the text of which contains the proper name Viscaya Zulanga, might transmit the message as follows: DC V DA BT BODY OF VISCAY A Z ULA NGA IMI VISCAYA ZULANGA JUST FOUND AR K 137. Delays during a transmission. —When it becomes necessary for an operator to stop during a transmission, he will, if the delay is to be of short duration, make the wait signal, AS, and if of long duration make the appropriate procedure signal (s). _ a. When the wait signal, AS, is used it will be repeated at least once every 30 seconds until transmission is resumed, and the last group sent prior to the interruption will be repeated in con¬ tinuing. Example— DA, while transmitting a message to DB, wishes to interrupt his own transmission in order to make some adjustment in his set, check on a group of the message he is transmitting, or for some similar purpose. He would transmit as follows: DB V DA NR7 GR10 BT NR4 DFC4 MRNF OZLU AS (30 seconds) AS (30 seconds) IMI _ OZLU KTRO VNVF HJTO EXYB GRQL I0I5P AR K b. When an operator expects a delay of long duration he will so notify the receiving operator (s) by the use of the proper pro¬ cedure signals. When such interruption occurs during the trans¬ mission of a message he will cancel the message and transmit it in its entirety when communication is resumed. (See example, par. 1296.) 138. Transmitting long messages. —When transmitting long messages the text will be broken up into portions, each por¬ tion not to exceed 50 groups at each transmission. In order to insure that each portion is received before proceeding with the next portion, the procedure signal B, followed by a numeral indi¬ cating the number of groups that have been sent, is used before the procedure signal K. If the receiving operator has received the first portion without error, he will answer with the procedure signal R, a numeral indicating the number of groups received, and K The sending station will then transmit the next portion, and again use the signals B and K. The receiving station will answer as before. When the message is completed, the sending operator will send AR K. The receiving operator will then receipt for the complete message. BASIC FIELD MANUAL 155 Example .—DA must send a message of 122 groups to station DC. After DA had called DC and DC had told him to “go ahead” he would transmit as follows: DC V DA NR5 GR122 BT (50 groups, the last group being XASP) XASP B 50 K DC would answer— DA V DC R 50 K DA would resume— DC V DA (50 more groups, the last group being JAPY) JAPY B 100 K DC would answer— DA V DC R 100 K DA would resume— DC V DA (and send the remaining 22 groups of the message) AR K DC would answer— DA V DC R NR5 VA Section IX ARTILLERY FIRE CONTROL 139. Control of artillery fire by radio. —The abbreviated form message is authorized for the exchange of communications controlling or directing the fire of artillery. Its use makes pos¬ sible the control of fire by radio, when the radio station of the observer and the radio station of the battery are in direct touch. The call signs of the radio stations concerned are considered as the address and signature groups of the officers in charge at those stations. The radio stations of the battery and of the observer must be in direct radio touch with each other to use this method. It is practically impossible to relay fire-control messages through linking radio stations. The term “radio station of the battery” is used to indicate the battalion radio station which will be in direct communication with the battery firing. a. When abbreviated form is used for the transmission of firing data only, no special prefixes are necessary and the message takes the following form: 1143°—31-6 156 BASIC FIELD MANUAL Transmission Meaning Call sign of the station called_Used as the address. y_From. Call sign of the station calling_Used as the signature. Wp_ Break sign. Text of message in secret or clear language. Wr ___End of message. This must be followed immediately by another message or by an appropriate procedure signal. b. Abbreviated forms for answering in controlling fire by radio are shown below: (1) Where a receipt is required only for a previous transmis¬ sion, the form will be as follows: Transmission Meaning Call sign of station called_Used as the address. y_From. Call sign of station calling-Used as signature. j>_;_Received. Followed by appropriate ending sign. (2) Where the nature of the answer is such as to indicate clearly that the previous transmission has been received, the received sign R need not be sent as shown in (1) above. This is illustrated in various examples which follow. (3) When a receiving station misses any part of the transmis¬ sion of a fire-control message in abbreviated form, a request for a repetition of the whole message will be made as follows: Transmission Meaning Call sign of called station_Used as the address. y___From. Call sign of calling station_Used as the signature. IMT- -_ Repeat previous transmission. K_ Go ahead. c. Three special procedure signals are used in controlling or directing fire by radio. Signal Meaning IX_ Message following is a preparatory command and is not to be carried out until the signal or command of execution is received. BASIC FIELD MANUAL 157 5-second dash-Signal (command) of execution. This is the command of execution and means execute the last preparatory command or the pre¬ paratory command indicated by the iden¬ tification data. It should be sent by the observer only. It is always preceded by a call and followed by AR. It should never be canceled or annulled. 2-second dash-Salvo mark (battery fired; i. e., on the way). This is sent by the operator at the battery radio station just as the battery fires. It may be followed by a numeral indicating the time of flight of the projectile in sec¬ onds if necessary or advisable. It is never preceded by a call and should be sent by the battery station only. (1) When it is desired to conduct fire by radio, the preparatory command s igna l, IX, is inserted in the heading of the message just before BT,_ provided the officer conducting fire desires the battery to^fire at his command. Operators receiving messages with an IX in the heading will know that the message following is a preparatory command and that a signal directing the execu¬ tion of it will follow shortly. The transmission of a preparatory command, in conducting artillerj' fire by radio, would be as fol¬ lows: Transmission Meaning Call sign of called station-Used as the address. V- From. Call sign of calling station-Used as signature. IX-_-Preparatory command _ follows. BT-- - Break sign. Text of message in secret or clear lan¬ guage. AR-End of message. AS, K or the transmission in (2)_Wait, go ahead, or the command of execu¬ tion. (2) To safeguard the 5-second dash or sign of execution and prevent a preparatory command from being executed prema¬ turely on account of a key sticking or the accidental transmission of a long dash, the 5-second dash must always be preceded by a 158 BASIC FIELD MANUAL call and followed by AR. Thus the preparatory command in (1) above may be executed at once by sending the following: Transmission Meaning Call sign of called station_ Used as the address. V- From. Call sign of calling station_Used as signature. 5-second dash- Execute preparatory _ command. AK---End of message. K-- Go ahead. If the observer desires he may send the call at any time previous to the 5-second dash. He can then keep contact with the battery by the wait signal AS until in position to observe, when the 5-second dash will be sent. (3) The battery station would then, if the preparatory message and the signal of execution has been received correctly, answer by sending a 2-second dash or salvo mark just as the battery fires. The salvo mark may be followed by a numeral indicating the time of flight, if necessary or advisable, thus: Transmission Meaning 2-second dash_Salvo mark. 35-Time of flight. K--*Go ahead. (4) If the battery station had failed to receive the preparatory command it would request a repetition as in b (3) above. d. The actual transmissions with their meanings are stated in (1), (2), (3), and (4) below for four separate cases. In all of the examples shown the transmission is single; i. e., groups are not repeated. When the two radio stations do not have easy radio communication with each other, the groups may be sent twice. No mention is made in any case of the position of the observer. He may be on the ground or in the air, as his location does not affect the form of message. For purposes of illustration, the following call signs will be used: Call sign of the observer—OB. Call sign of the battery—BA. (1) Case No. 1 .—An observer who is in a position to make continuous observations establishes a radio station and calls the battery telling them he is ready to observe. He then observes several shots, as follows: BASIC FIELD MANUAL 159 (a) The observer reports that he is ready. Transmission Meaning BA- Battery’s call sign. V-From. OB-- Observer’s call sign. BT- Break^sign. 01-Will observe fire of unit in- _ dicated. AR-End of message. K_ Go ahead. (6) The battery answers, giving the target, and then fires. Transmission Meaning OB_ V _ BA_ BT_ OS_ UB_ 394 7_ AR_ 2-second dash__ 35_ K_ (c) The observer calls the observation. Transmission BA_ V _ OB_ BT_ 044_ RR_ SS___ AR_ K_ Observer’s call sign. From. Battery’s call sign. Break sign separating head¬ ing and text. Observe fire-on. Target at. 3947. End of message. Salvo mark. Time of flight. Go ahead. battery and gives them his Meaning Battery’s call sign. From. Observer’s call sign. Break sign separating head¬ ing and text. 40. Right. Short. End of message. Go ahead. 160 BASIC FIELD MANUAL ( d ) The battery fires and sends a salvo mark. Transmission Meaning 2-second dash__ Salvo mark. 40_Time of flight. K_ Go ahead. (e ) The observer calls the battery and reports the accom¬ plishment of his mission. Transmission Meaning BA_Battery’s call sign. V _From. OB_Observer’s call sign. BT_Break sign separating head¬ ing and text. RZ_ Result accomplished. AR_End of message. K_ Go ahead. (/) The battery calls the observer and tells him that the problem is ended. Transmission Meaning OB_Observer’s call sign. V _From. BA_Battery’s call sign. BT_Break sign. RZ_Result accomplished. AR_End of message. VA_Communication finished, no reply required. (2) Case No. 2 .—An observer who is not in a position to observe fire continuously wishes the battery to fire at his command. BASIC FIELD MANUAL 161 (a) The observer calls the battery and instructs them as follows: Transmission Meaning BA_Battery’s call sign. V _From. OB_Observer’s call sign. IX_Preparatory command fol¬ lows. BT_Break sign. 01_Will observe fire of unit indicated. MC_Fire at my command. AR_End of message. K_ Go ahead. ( b ) The battery calls the observer and gives him the tar¬ get and states that the battery is ready to fire. Transmission Meaning OB_Observer’s call sign. V _From. BA_Battery’s call sign. BT_Break sign. OS_Request observation. UB_On target at. 3947_ 3947. BY_Battery ready. AR_End of message. K_ Go ahead. (c) The observer calls the battery and tells them to fire. Transmission Meaning BA_Battery’s call sign. V _From. OB_Observer’s call sign. 5-second dash_ _ Execute preparatory com¬ mand. AR_End of message. K_ Go ahead. (d) The battery fires, sending a salvo mark to the ob¬ server at the same time. Transmission Meaning 2-second dash _ _ Salvo mark. 35_Time of flight. K_Go ahead. 162 BASIC FIELD MANUAL (e) The observer calls and gives his observations. Transmission Meaning BA_ Battery’s call sign. V_ From. OB_Observer’s call sign. IX_Preparatory command fol¬ lows. BT_Break sign. 044!___40. RR_ Right. 202_ 200. 00 _ _Over. AR_End of message. K_Go ahead. (/) The battery station misses a part of the message and asks for a repeat. Transmission Meaning OB_Observer’s call sign. V _ From. BA_ Battery’s call sign. IMI_Repeat previous transmis¬ sion. K_Go ahead. (g) The observer calls the battery and repeats the whole message. Transmission Meaning BA_Battery’s call sign. V _From. OB_ Observer’s call sign. IX_Preparatory command fol¬ lows. BT_Break sign. 044__40. RR_Right. 202_ 200. 00 _ _Over. AR_End of message. K_ Go ahead. BASIC FIELD MANUAL 163 ( h ) The battery calls the observer and states it is ready to fire. Transmission Meaning OB_ Observer’s call sign. V_ From. BA_ Battery’s call sign. BT_ Break sign. BY_ Battery ready. AR_ End of message. K_ Go ahead. ( i ) The observer calls the battery and tells it to fire. Transmission Meaning BA_Battery’s call sign. V_From. OB_Observer’s call sign. 5-second dash. _ Execute preparatory com- * mand. AR_End of message. K_ Go ahead. { j ) The battery transmits a salvo mark indicating that the battery fired. Transmission Meaning 2-second dash__ Salvo mark. K_ Go ahead. The observer calls, reports, and the battery fires until the mission has been accomplished. (3) Case No. 3. —An observer wishes to conduct fire. (a) He calls his battalion, reporting target, and states that he can adjust upon it. Transmission Meaning BA_Battalion’s call sign. V_ From. OB _Observer’s call sign. BT_. _Break sign. YK__ _Counterattack. FT_ Concentrating at. 4267__ 4267. WA_ Will adjust on target just re¬ ported. AR-. _End of message. K_ Go ahead. 164 BASIC FIELD MANUAL (6) The battalion answers, assigning a battery. Transmission Meaning OB_Observer’s call sign. V_From. BA_Battalion’s call sign. BT-_ _Break sign. Cl 1 _ Battery B will fire. AR-- _ End of message. K_ Go ahead. (c) The observer wishes the battery to fire at his com¬ mand in order to place the first salvo on a cross¬ road just as the target approaches it. The pro¬ cedure sign IX is inserted in the heading so that the firing data will be treated as a preparatory command. Transmission Meaning BA_Battery’s call sign. V_From. OB_Observer’s call sign. IX-- _Preparatory command fol- _ lows. BT-_ _Break sign. BD_ Base deflection. LL_Left. 120_120. SI_Site. 295_ 295. SP_Shrapnel. KR_ Corrector. 35_35. B1_ Battery one round. MC_At my command. 400_ 400. ' MM _More. AR-- _End of message. K_ Go ahead. 1 This group can be a prearranged code designation of Battery B if desirable. BASIC FIELD MANUAL 165 (d) The battery answers that it is ready to fire. Transmission Meaning OB_ _ _ Observer’s call sign V_ From. BA_ Battery’s call sign. BT_ Break sign. BY_ Battery ready. AR_ End of message. K_ Go ahead (e) The observer is not ready for the battery to fire, so he answers, receipts for the message, and tells them to wait. Transmission. Meaning BA_Battery’s call sign. Y_ From. OB_Observer’s call sign. WM_Wait a few minutes. AR_End of message. AS_Wait. The observer should make the procedure signal AS every 30 seconds. This is done in order that the battery radio operator will know he is still receiving the observer’s station. In the same manner, if it is necessary for the battery operator to keep the ob¬ server waiting, he will send AS every 30 seconds. (/) When the observer is ready for the battery to fire he sends— Transmission,. Meaning BA_ Battery’s call sign. V_ From. OB_ Observer’s call sign. 5-second dash__ Execute preparatory mand. AR_ End of message. K_ Go ahead. com- (i g) The battery replies with a salvo mark but sends no time of flight, as the observer has the data al¬ ready. He is conducting the fire. Transmission Meaning. 2-second dash__ Salvo mark. K_Go ahead. 166 BASIC FIELD MANUAL (4) Case No. 4- (a) If the observer in (3) (/) above desires that the battery- fire as soon as it receives the data, he will send as follows: Transmission Meaning BA_Battery’s call sign. V_ From. OB_Observer’s call sign. BT_Break sign. LL_Left. 30_30. LC_On No. 4 close. 5_5. D_ Down. 5___5. SR_Salvo right. 200 _ 200 . LS_ Less. AR_End of message. K_ Go ahead. It must be noted that in this case IX is left out of the heading and the battery will fire as soon as the range is given. The battery fires and sends a salvo mark. (6) Assuming now that the battery and observer (or battery commander) are working well together, and that there is no interference, the transmission might take the following form: Transmission Meaning RR_ Right. 10_ ___ 10. FO_ _ On No. 1 open. 3_ ___ 3. U_ — Up. 3 _ ___ 3. B2_ Two rounds. SM_ Same. RG_ Range. AR_ _ End of message. K_ _ _ Go ahead. (c) This procedure is continued until the mission is accomplished. BASIC FIELD MANUAL 167 Section X ’ PROCEDURE SIGNALS 140. Rules governing use of procedure signals.— a. The use of a procedure signal with any meaning other than that pre¬ scribed in paragraph 141 is prohibited. b. Procedure signals commencing with Z (“Z” signals) which have an affirmative meaning are given a negative meaning by adding “ZPA” to the signal. Example .—“ZAG ZPA DC” means "Am not in communi¬ cation by radio with DC.” c. Procedure signals having an affirmative meaning can not be given an interrogatory meaning by use of INT, I MI, or any modification other than that indicated above. If a signal con¬ veying the desired meaning does not exist, a message must be « employed. d. Referring to meaning of procedure signals as given in para¬ graph 141, the following rules must be observed in making use of those which involve, or may involve, an additional transmis¬ sion to complete the meaning as indicated by the blank space (s). (1) All blank spaces not inclosed in brackets must be filled in to complete the meaning of the signal. ($2) A blank space (s) inclosed in brackets either change (s) (if statement commences with “or”) or add(s) to the basic meaning of the signal, and may or may not be filled in to complete the meaning. (3) In using signals with blank spaces filled in to convey the desired meaning, the signal is always sent first (followed by ZPA, if necessary), followed by the additional information in the same order as the blanks appear in the meaning of the signal. Example— li ZAK400P THREE SEVEN FIVE” means “Call me again at 4 p. m. on 375 KCS.” (4) Referring to (1) and (2) above, whenever it is required that blank spaces occurring before the word “message (s) ” be filled, both the number of messages of each class and the class will be given in full. If it is not necessary to fill such a blank space, the desired meaning may be conveyed by omitting either the number of messages of each class, or the class, or both. Examples .—‘‘ZAR ONE 0 AB II TWO P ONE DC” means “I have one urgent message for AB and two priority and one routine for DC.” The answer to this might be: “ZZH,” meaning “Transmit all messages.” 168 BASIC FIELD MANUAL “ZZH O ,” or “ZZH AB,” meaning ‘‘Transmit your urgent message to AB.” ‘‘ZZH 0 II P,” meaning “Transmit your urgent and priority messages/’ or “ZZH AB II ONE P DC/’ meaning “Transmit your message to AB and one priority message to DC,” etc. (5) Whenever a blank which follows the word “message(s) ” is filled, the number sign, NR, and the station serial number(s) concerned must be used. If the message (s) in question did not carry serial number(s), other identifying data may be inserted. The signal will be used alone only when no convenient method of identification is available, and then only in referring to the last message transmitted. Example 1 .—“ZBZ NR3 TO 6 K” means “Are you certain of the reception of my messages Nos. 3 to 6, inclusive?” Example 2 .—“ ZCX ABC” means “ Have you received my message sent after the met call?” Note. —Collective call messages do not carry serial numbers. Example 8. —“ZCX” means “Have you received my last message?” Note. —Referring to an abbreviated form message, which would not carry a serial number. (6) Whenever numerals are used in filling in blanks to com¬ plete, change, or amplify the meaning of a procedure signal, words will be substituted for the numerals in the actual transmission, except in the case of station serial numbers, group numbers, and numerals appearing in a time group. 141. List of procedure signals.—The following procedure signals are prescribed for communication between the Army and Navy and in all Army tactical nets: _ Signal Meaning AAA_Blank, representing missing or doubtful por¬ tions. A A_All after_(to be used in requesting a repetition or verification). AB_All before_(to be used in requesting a repetition or verification). AR_End of message. Wait. AS BASIC FIELD MANUAL 169 Signal Meaning B_There is more to follow. BN_All between (to be used in requesting a repetition or verification). BT_Break, separating heading and text. C_You are correct. EEEEEEEEEE__ Error. F_ Do not answer. G_Repeat back. GR _Group (s). HM_Silence. II- _ _Space. IMI __Repeat, I will repeat, interrogatory. INT_Is this correct? IX... _ Message following is a preparatory command not to be carried out until the signal (command) of execution is received. 5-second dash_Signal (command) of execution. 2-second dash_Salvo mark (battery fired; i. e., on the way). J_Verify and repeat. K_ Go ahead (i. e., answer—and ending sigpal). N_ Nothing (or not) received. NR_Number. O_Urgent. P_Priority. R_Received or readability (according to con¬ text) . S___Signal strength. T_Transmit to_ TOFO_Time of origin. TOR_Time of receipt. U_Radio guard (Navy). Net control station _ (Army). UO_Negative silence. V-. _From. VA_End of communication; finished; (and ending signal). W_Interference. WA_Word after_(to be used in requesting a repetition or verification). X_Static interference. ZAA_Call me by wire telephone. 170 BASIC FIELD MANUAL Signal ZAB_ ZAC_ ZAD_ ZAE_ ZAF_ ZAG_ ZAH_ ZAI_ ZAJ_ ZAK_ ZAL_ ZAM_ ZAN_ ZAO_.. ZAP_.. ZAQ_ ZAR.. ZAT ZAU ZAV. ZAW ZAX. Meaning Are you in communication by visual with _? Are you in communication by radiotele¬ phone with_? Am in communication by visual with -(through_). Am in communication by radiotelephone with_ Are you in communication by radio with __? Am in communication by radio with_ (through_). Have you heard_? It is forbidden to transmit (until_). Try radiotelephone (on_KCS). Call me again at_(on_KCS). Can you hear-? If so, what is his signal strength? Can hear_; his signal strength is_ Did-send anything for me? If so, please repeat. Following is what _ sent (at _o’clock). Have (or-has) been calling you since-(on_KCS). Of what class and to whom are your mes¬ sages? Have -messages for_ (If blanks not filled means “Have a mes¬ sage for you”). -reports radio telephone_ I (or-) will call you again as soon as I (he) can (or at_o’clock) (on ______ KCS). -is calling you (on__KCS). Inform___that I am calling him (on_KCS). Nothing received from _ (at .-). BASIC FIELD MANUAL 171 Signal ZAY_ ZAZ. ZBA_ ZBB_ ZBE_ ZBF_ ZBG._ ZBH_ ZBJ_ ZBK_ ZBM ZBN. ZBO. ZBP_ ZBQ. ZBR. ZBU. ZBV. ZBW ZBX. ZBY. Meaning Report when you are in communication by visual with_ Report when you are in communication by radio with_ Wait, I must shift to copy another station (or-) but will call you as soon as I can (or at_o’clock). Radio telephone indistinct, send by key. Whom shall I call, and on what frequency, to report - messages for_ _ ? Report messages to_(on_ KCS). Through whom shall I relay _. messages for_? May I relay _ messages for _ through you or (through - )? Have nothing to transmit. Reception impossible. Send series of six dashes if transmission received or send series of six dots if transmission not re¬ ceived. Send receipt for message when communication next established. Fragments only received (from_). Send each message twice. I have difficulty receiving. Send each message once only. Reception is good. Send faster. Send slower. You are missing dots. Your Morse is difficult to read. Reception very bad; send each group_ times. Reception exceptionally bad; send each character_times. Reception impossible. Accuracy of reception of message_ is doubtful. 172 BASIC FIELD MANUAL Signal Meaning ZBZ_Are you certain of accuracy of reception of message (s) __ (or of group (s) _in message_:_)? ZCA_Cease listening in for messages from ZCB. Groups_in message- should apparently read as follows: ZCC_Has executive sign (signal of execution) for last message (or for message following _) been made? ZCD__Have you received the signal to execute last message? ZCE__ Can not trace message referred to. Give more references. ZCF_Have you received SOS just made (by _) (at_o’clock)? ZCG_Listen in for messages from-(on _KCS). ZCH_Letter each group (in message-). ZCI_I will letter each group (in message -)• ZCJ. Message (_) does not concern you (or-). ZCK_ Message which you just forwarded was in¬ correctly transmitted. ZCL_ Message following was incompletely received; groups missed are indicated by the “blank sign” (AAA). ZCN_ Number of groups (in message-) was_ ZCP_Repeat message(s) from —•_- (at _o’clock). ZCQ_Reply to message_— is to be trans¬ mitted now. ZCR_Cancel this message. ZCT _ _ Following is correct version (of message _ )• ZCU_The following is heading of message (_) as received. Check to origin if necessary and repeat. BASIC FIELD MANUAL 173 Signal Meaning ZCV_Transmit your message in strings of ZCW_ Am going to transmit messages in strings of ZCX_ ZCZ. ZDA_ ZDB_ ZDC_ ZDD. ZDF_ ZDG_ ZDH. ZDM ZDN. ZDP_ ZDR_ ZDV_ ZDW ZDX. ZDY_ ZDZ_ ZFA_ ZFJ_ ZFK ZFL. ZFM Have you received my message_? Delay was due to fault in my receiving apparatus. Delay was due to fault in my transmitting apparatus. You are causing delay by slowness in answering. You are causing delay by answering out of turn. Request immediate reply to my message (-). Send receipt for message (_) when communication next established. Transmit all your messages one after the other. When may I expect an answer to my message _? Continuous frequency. Vacuum tube transmission. Land wire or cable. Radiotelephone. Tonic train (chopped CW) transmission. Visual. Frequency. Type_transmitter. Type_receiver. Model_receiver. _is radio guard on _ KCS (net control station for net whose call is_). Am ready to take over radio guard (to act as net control station). Are you radio guard (net control station) (for__)? Indicate ships (stations) for which you are radio guard (net control station). 174 BASIC FIELD MANUAL Signal ZFQ_ ZFW_ ZFX_ ZFZ_ ZGA_ ZGB_ ZGC_ ZGD_ ZGF_ ZGG. ZGJ_ ZGK. ZGL_ ZGM ZGN. ZGO- ZGP_ ZGQ_ ZGR. ZGS. ZGT. ZGU- ZGV_ ZGW ZGX. ZGY. ZGZ_ ZJA_ ZJB_ ZJC_ ZJD_ ZJF_ Meaning (-) Act as___(until_ o’clock) (on_KCS). Am in your zone. Relay communications for me. Expect to be out of communication for radio until _ o’clock. Handle radio communication for this ship (station). Am (or_is) unable to_ Are you (or_is) unable to_? Am going to use (or am shifting to)_ Am (or_is) unable to use_ Am (or_is) using. Use_ My antenna (or antenna of_) has been damaged (or carried away). My receiving apparatus is temporarily out of commission. Repairs completed. Am in commission. There appears to be something wrong in your (_) receiving equipment. There appears to be something wrong in your (_) transmitter. My_(or_of___) is defective. Your_appears to be defective. I can not transmit on_KCS. Your antenna appears to be grounding. At the end of this transmission I (or_) will transmit on CW. I have increased my radiation. My radiation is good. I can not receive (_). How is my note?. Lower your note. Raise your note. Your note is bad. Your note is clear and musical. Your note is rising and falling. Decrease strength of signals. Increase strength of signals. How are my signals? What is my signal strength? BASIC FIELD MANUAL 175 Signal ZJG_ ZJJ_ ZJK_ ZJL_ ZJM_ ZJN_ ZJQ_ ZJR_. ZJV_. ZJY_. ZJZ_. ZKA_ ZKC. ZKG. ZKH. ZKM ZKN. ZKO- ZKP. ZKQ. ZKR. M eaning Your signals are unreadable owing to your bad note. Your spark is broken. Your signals fade. Cease using_ Act as relay between me and_ Give me your message for_; I will forward it. Inform me when this message (or message -) has been received by the addressee (or by_). Message_has been received by the addressee (or by_). Message (s)-has (have) been sent by land wire. Take no further action with regard to for¬ warding message_(to_). Transmit this message now (or at_) by “F” method. Transmit this message now (or at_) without preliminary call up. Transmit this message now (or at_) by intercept method. Pass following message to destination by dispatch mail system. Distribute this message by - dispatch where no charges are involved and to all others by mail. Forward this message by commercial nite letter. Send V’s on your present frequency (or _KCS). Am going to send V’s on my present fre¬ quency (or_KCS). Am going to transmit on_KCS. Am shifting to receive on_KCS. Am (or-is) unable to transmit on_KCS. Am (or KCS. ZKU is) transmitting on_ 176 BASIC FIELD MANUAL Siqnal ZKX_ ZKY_ ZKZ_ ZLA_ ZLB_ ZLC_ ZLD_ ZLF_ ZLG_ ZLH_ ZLJ__ ZLK_ ZLL_ ZLV_ ZMC. ZMF_ ZMG. ZMJ_ ZMK. ZML_ ZMM ZMN. ZNO- ZNP. Meaning On receiving “K” on-KCS I shall (or_will) transmit message to you on _ KCS. Answer on your present frequency (or-KCS). Shift to receive on_KCS until further orders. Shift to_KCS. Transmit and receive on-KCS. What frequency are you (or is-) using? How is my frequency? Your frequency appears to be correct. Increase your frequency a trifle (or-- KCS). Decrease your frequency a trifle (or- KCS). ' Your orientation is wrong; check it immedi¬ ately. Transmit on-KCS. Shift from telegraph to compensating fre¬ quency or vice versa. Check your frequency. General call; all stations copy. Who is interfering with you? I am being interfered with by- (on_KCS). Listen in before transmitting. You are causing unnecessary interference. Do not interfere, I am receiving from- You are causing interference. You are causing interference by inattention to order to wait. You are causing interference. Send on another frequency. You are sending at the same time as-. Answer_and take his message (s). Answer calls for me (or for-). BASIC FIELD MANUAL 177 Signal ZNU_ ZNV___ ZPA_ ZPB_ ZPF_ ZPG_ ZPH_ ZPJ_. ZPN_ ZPO_ ZPP_ ZPR_ ZPV_ ZPW ZPX. ZQO. ZXA. ZXB. ZXC. ZXD Meaning Answer in alphabetical order of call signs. Answer in_KCS. Negative, No, Not. (For use with operating signals only.) Affirmative, Yes. (For use with operating signals only.) Send - (weather, obstruction, storm warnings, press, etc.) last received (or received at _) to me (or to - ). Set clocks to_o’clock upon receiving signal of execution. What time is it? Message-undelivered; addresses unknown. Message_- undelivered; station out of range. Message_refused. Message undelivered; addressee no longer here (or not here). Message-accepted by- State if correct. Address on message_is_ Try again. Address on message_insufficient. Give better address. Message-now delivered O. K. Send report of weather conditions your vicinity. What was station serial number of last mes¬ sage received from this station (or from --)? Station serial number of last message received from you (or from_) was_ What was station serial number of last message you transmitted to me (or to --)? Station serial number of last message trans¬ mitted to you (or to_) was 178 BASIC FIELD MANUAL Signal Meaning iXF- Prior to closing station records, last message transmitted to you (or to_) was message-; last message received from you (him) was message_; (last message transmitted to_ was message -; last message received from him was message_). Note—R epeat for as many stations as necessary to complete the check. ZZA 1 ZZB i ZZC 1 ZZD i ZZF i. ZZH_ ZZK 1 Station reports into the net. Station leaves net temporarily (or for_ hours) (to communicate with_). (Will be on_KCS.) Is net directed or free? Net is directed. Net is free. Transmit (-) message (s) (to -) (on_KCS). The following stations are now in the net: ZZO 2 -Broadcast your messages without preliminary call up. ZZP 2 -Do no £ broadcast. Call your station first. ZZX-Close your station. USA- General call. Any Army station hearing v/ill answer. USN- General call. Any Navy or Marine Corps stations hearing will answer. Section XI DRY BATTERIES 142. General construction.— a. The common form of dry cell is contained in a zinc can which serves both as the battery jar and as the negative electrode. This can contains as electro¬ lyte a solution of ammonium chloride, generally called “sal ammoniac,” dissolved in water and mixed with some absorbent material such as flour, starch, etc., to form a jelly or paste. 1 This signal is not in the Navy list. It should not be used in communication with naval stations. 2 The term broadcast as here used means that the call up and answer may be omitted. (See par. 123 a (3).) BASIC FIELD MANUAL 179 Thus the dry cell is really not dry, but is sufficiently wet to be¬ have electrically like a wet cell. b. The positive or center pole of the cell is a carbon rod, which is surrounded by carbon dust held in a cloth bag. The space between this bag and the paper lining of the zinc can is filled with manganese dioxide and the whole is saturated with the electro¬ lyte. c. The interior of the cell must be kept moist, and this is accomplished by an inner seal of paraffin poured on top of the material between the carbon rod and can and by an outer seal of sealing compound poured on top of and separated from the paraffin by a cardboard disk. 143. Care of dry cells.— a. As dry cells are supplied com¬ pletely assembled, the first part of their care pertains to the con¬ ditions of storage. All cells will deteriorate to a certain extent in storage, due to local chemical action within the cell and on the zinc can. There is no method of preventing this, but the effects can be reduced to a minimum by keeping the cells in storage at ordinary temperatures for the minimum length of time. In general, the deterioration is more rapid in the case of small cells and at the higher temperatures. Thus if a small-sized low- grade cell is kept in storage under average conditions for a few months, it may be nearly useless when withdrawn for service. On the other hand, a large sized high-grade cell may often be kept in storage for six months and yet give nearly as good service as when new. b. The best practice would be to obtain a supply of cells from the manufacturer as they are needed and to issue them imme¬ diately. This is approximated as closely as practicable, yet cells must generally be kept for a certain length of time in storage. This necessary time in storage may be reduced if the user of dry cells submits his requisitions at frequent intervals for quantities actually needed and without attempting to set up a local reserve supply. c. In order to tell the age of the cells, the date of manufacture is generally stamped on the cardboard case or carton. When cells are withdrawn for use the oldest in storage should be with¬ drawn first in order that no cells will be used which have deterio¬ rated to any serious extent. d. Dry cells should be kept free from dirt and moisture in order to avoid short circuits. 180 BASIC FIELD MANUAL e. Individual cells are contained in a cardboard case or carton, which serves principally to insulate the zinc can, but also to a certain extent to protect the zinc aginst mechanical injury. The carbon should not be removed from the cell in ordinary use. Section XII STORAGE BATTERIES 144. General.—The following brief discussion is intended for the user of Signal Corps storage batteries in the field. TR 1190-5 (now printed as TR 1160-5), which is a much more complete discussion, is provided for the information of the specialists assigned to battery-charging stations. 145. Charging and discharging.—The storage battery gen¬ erates electricity by chemical reaction, but before it can generate electricity it must first be charged. In other words, a direct current from an outside source of electricity, commonly called a generator, must be sent through the battery. Usually this current is applied for a number of hours until the necessary chemical changes have taken place inside the battery. The battery is then ready for use. When current is taken from a storage battery the battery is said to be discharging. After a battery has been used for a certain number of hours it becomes discharged and can not be used again until the charging process is repeated. 146. Lead-cell battery.—For communication purposes, the Army uses lead-cell batteries. These cells consist of a hard rubber or composition jar in which are placed two sets of lead plates. The plates of one set, fastened together to a common terminal, form the negative group of the battery, while the plates of the other set, also fastened together to a common terminal, form the positive group of the battery. The negative plates are made with small rectangular indentations or pockets on both sides. These pockets are filled with active chemical material. The positive plates are made in the same manner, but are filled with a different active chemical material. The group of negative plates is immeshed with the group of positive plates in such a manner that beginning from one side of the cell the first plate is negative in polarity, the next plate positive, the next negative, and so on. In order to keep the plates from touching one another, wooden or hard-rubber separators are placed between the plates. The cell jar is filled with a dilute solution of sulphuric acid. BASIC FIELD MANUAL 181 147. General description. —The batteries used in the Army for field radio purposes consist of two cells. In order to protect the cells against damage, they are inclosed in a strong wooden box or are mounted in a monoblock container and provided with a carrying strap. 148. Capacity or ampere-hour rating. —The capacity of a storage battery is represented by its rating in “ampere-hours.” This rating theoretically represents any discharge rate in amperes multiplied by the number of hours the battery may be discharged at that rate. For instance, the BB-29 battery is rated at 90 ampere-hours. Theoretically it will deliver 90 amperes for 1 hour or 45 amperes for 2 hours. These rates of discharge, however, are too great, and in a very short time would cause the battery to become completely ruined. It is necessary therefore to discharge this battery at a lower rate. Experience has determined for each battery a rate of discharge which can not be exceeded without injury to the battery. This rate is called the normal rate of discharge for the battery. For the BB-29 this normal rate is 18 amperes; it will deliver this current for 5 hours. It will deliver a smaller current for a correspondingly longer time, 9 amperes for 10 hours, 5 amperes for 18 hours, 1 ampere for 90 hours, etc. 149. Spilling acid. —The storage batteries used by the Army for field service are of the nonspill type. However, this will not prevent the acid from leaking should the battery remain over¬ turned for more than a few moments. To avoid leaking always keep the storage battery in an upright position. If any acid should spill or leak from the cell it must be carefully wiped off at once as it causes corrosion of the cell terminals. Take care never to get the acid on the hands or clothing as it will cause a burn on the body or eat holes in the clothing. 150. Keeping terminals clean.— The action of the acid on the terminals of the cell is such as to cause a green insulating material to collect upon them. Should this material collect in too great quantities it will thoroughly insulate the terminal, thus making it impossible to secure a good contact. Care must be taken that both terminals of the storage battery are kept clean. 151. Testing. —-Never short-circuit a storage battery to determine its state of charge, as this may buckle the plates and permanently ruin the battery. A storage battery should be tested in the field by means of a voltmeter. When the battery is fully charged the voltage should be from about 2.0 to 2.2 182 BASIC FIELD MANUAL volts per cell. The voltage drops as the battery is used, until when completely discharged the e. m. f. is about 1.8 volts per cell. When a partially discharged storage battery has been removed from the circuit, its open-circuit voltage gradually increases, although the true condition of the battery has not appreciably improved. When the battery is again connected in the circuit this “recovered” voltage is rapidly reduced to a value corresponding to the state of charge of the battery. It is therefore apparent that the voltage reading should be taken after the battery has been connected in a circuit and has been dis¬ charging for a few minutes. 152. No testing by ammeter.-—As the short-circuit current of a storage battery is very high it is impracticable to determine its serviceability by the short-circuit test. Under no conditions should an ammeter be connected across the terminals of a storage battery, as this action may result in the burning out of the meter. 153. Using one cell.—Sometimes it may be necessary to use only two volts instead of four volts. If only one cell of the bat¬ tery is used the cells should be used alternately so as to discharge the cells to the same degree. This is to facilitate charging. 154. Dropping batteries.—The case of each cell is made of hard rubber which, if subjected to severe usage, will crack and allow the acid to leak. The battery, therefore, should never be thrown down on the ground or dropped. 155. Height of electrolyte.—The maintenance of the proper quantity and density of electrolyte is ordinarily the duty of the battery charging personnel, adjustment being made at the charging station each time the battery is returned. When a battery is to remain away from the charging station for more than three days, however, the maintenance of the proper level of electrolyte becomes the duty of the user. In such a case the battery should be inspected daily and the proper level, y 2 inch over the tops of the plates, should be maintained by the addition of the purest water available, preferably distilled water. 156. Maintenance of charge.—A fully charged battery loses between one and two per cent of its charge each day when standing idle and if allowed to remain partly or fully discharged for a long time the battery becomes greatly deteriorated. Every battery should be returned to the charging station at least once a month whether or not the battery has been used. BASIC FIELD MANUAL 183 157. Tactical replenishment. —There are three sets of storage batteries issued for each radio set. Assuming con¬ tinual radio operation, one set of batteries will be in use, another on charge and the third set en route to or from the charging station or else fully charged and in reserve at the radio station. Because of the difficulty of resupply of batteries during an attack, it is very desirable that each radio station be equipped with fresh batteries before the attack begins. 158. Data table. —The following data are given for the two batteries most used for communication purposes: Battery type No. Volts Capacity in ampere- hours Normal discharge rate in amperes not to be exceeded Weight of battery complete (pounds) Material of case BB-29_ 4 90 18 38 Hard rubber monoblock. BB-41_ 4 16 3. 2 13M Steel. CHAPTER 4 VISUAL SIGNALING Paragraphs Section I. Lamps_ 159-166 II. Flags_ 167-174 III. Pyrotechnics_ 175-179 IV. Panels_ 180-183 Section I LAMPS 159. Reference. —For general remarks on visual signaling and use of lamps, see chapter 8, Basic Field Manual, Volume VIII. 160. Equipment.—Signaling lamps are made in two sizes, called the 14 and 24 centimeter lamps, respectively. These dimensions indicate the diameter of the reflector. The 24- centimeter lamp consists of a portable searchlight, similar in principle to an automobile headlight, but equipped with a sighting or aiming tube on top, a hinged lid to cover the glass reflector, and a 2-wire cable used to connect the batteries for lighting the bulb. The battery consists of eight dry cells in series, carried in two leather pouches, each pouch holding four cells. These pouches are attached to a leather belt supported by shoulder straps. The belt has also an additional pouch in which three extra lamp bulbs are carried. A brass push button which projects through this pouch serves as a telegraph key for completing the battery and lamp circuits. The working of this key produces signals of short or long flashes. Connection between the lamp and socket is completed by the 2-wire cable and the plug and socket connector. The complete apparatus, com¬ prising the lamps, belt, three spare light bulbs, and eight dry batteries, is furnished in a wooden carrying case. The 14- centimeter lamp is similar to the 24-centimeter but smaller, using a battery of four dry cells and being slightly different in the manner in which it is carried. 161. Care.— a. The reflecting apparatus of a lamp is carefully adjusted before it is issued. However, it is possible that a slightly different adjustment will give better results when a new 184 BASIC FIELD MANUAL 185 bulb is inserted. To focus the lamp, the light is flashed against some dark background, such as a wall a few yards away, and the screws supporting the parabolic mirror are carefully turned until the light becomes concentrated in the smallest possible circle. The adjustment screws are then carefully tightened. b. The following precautions are necessary in lamp signaling: (1) Lamp cover is closed when lamp is not in use. (2) Cover is opened at start of transmission. (3) Mirror should not be touched except to clean with gauze or cotton or clean water. (4) Wire cable connections must be secure and durable. (5) Broken or burned-out bulbs should be thrown away unless otherwise ordered. (6) The lamp should not be used for illuminating purposes. 162. Use. — a. The lamp is constructed so as to project a beam of light whose rays are parallel. This tends to limit observation to those for whom signals are intended and increases the range of the beam. 6. The following approximate ranges are obtained with the two authorized types of with the naked eye: signal lamps under favorable conditions Type Diameter of reflector (centi¬ meters) Day range (yards) Night range (yards) EE-6 _ ! ..... 14 1,100-3, 300 2, 200-6,600 EE-7 ____ 24 1,100-6, 600 3, 300-11,000 The maximum ranges indicated above can be obtained only under most favorable conditions of atmospheric visibility and fixed operating conditions. Signals may be transmitted by using either white or red bulbs. At night the white bulb is visible at a greater distance than the red, but in daylight the red bulb has greater visibility. c. In lamp signaling one of the chief difficulties is that of acknowledgment. It is a general principle that lamp signals will be confined to signaling from the front toward the rear, acknowledgment being made at the rear station by means of pyrotechnics or some means other than by flag or lamp. This tends to prevent the location and consequent destruction of sta¬ tions by the enemy. Since lamp stations are usually estab- 186 BASIC FIELD MANUAL lished near command posts, the knowledge of these locations is also extremely valuable to the enemy. Situations will occur, however, especially in the Field Artillery and during open war¬ fare, when communication is equally feasible in both directions. When such is the case acknowledgment is made by the same means as is used in sending. The fullest possible use should be made of lamps in order to insure that lamp operators will be proficient when occasions arise which will demand or favor lamp signaling. d. Lamps are essentially a means for signaling over short dis¬ tances and are used to the best advantage within the battalion. To operate efficiently over longer distances, their use is confined to stabilized situations where time permits of the accurate loca¬ tion and testing of stations with reference to one another. At certain times it is possible to signal from battalion to regiment and from regiment to brigade, but the occasions are few in open warfare. In all transmissions the rays of the sending station must be directed upon the receiving station and acknowledgment made. Blind messages (messages receipt of which is not ac¬ knowledged) are of little value. The greater the distance be¬ tween stations, the greater-the need for accuracy in ray direction. For long distances, the alignment of the beam upon the distant station usually requires much time. Hence lamps are used generally over the shorter distances where the receiving station can be seen and the lamp readily sighted. e. Lamps may be used both for day and night signaling. The range for day signaling is shorter than that for night Signaling. By day, light conditions are less constant. Shadows, reflections, and weather conditions materially affect sending efficiency. It is best for day signaling to place the lamp in a deep shadow where the light conditions have less effect on the prominence of the beam. Sunlight falling on the face of the lamp may produce a continuous glare from the reflector and make the electric light signal undistinguishable. It is essential that the lamp be held firmly and the sighting tube aimed exactly at the receiving station during signaling. A slight movement of the lamp makes signals appear blurred or entirely invisible to the receiving station. A lamp may be held in the hand while signaling, but it is preferable to fasten it to something which will aid stability. BASIC FIELD MANUAL 187 163. Training.—The steps to be followed in training lamp operators are as follows: a. Learning the general service code, as applied to lamp sig¬ naling. b. Learning the conventional signals and procedure signs used with the lamp. c. Inside and outside practice in transmission and reception of signals over distances which permit of verbal communication between stations or groups. d. The transmission and reception of messages and signals between stations or groups located beyond speaking distance. e. Instruction in the use of the compass and map reading. /. The establishment, operation, and maintenance of visual stations under assumed tactical situations. g. It is a mistake to assume that an operator accustomed only to signals received by the ear can without further training read lamp signals or transmit lamp signals satisfactorily. Such an operator, however, with a few days’ training, should develop into a good lamp signalman. 164. Procedure signs.— The following procedure signs are used: AR—End of message, sent (. — . — .) and not (. — . — .) B—More to follow (— . . .) E (ten times)—Error or Erase (.) K—Go ahead (— . —) AS—Wait (-) V—From (. . . —) 165. Message transmission. — a. In message transmission, every time a letter can be omitted the chance of error is reduced. For beginners or in other eases where slower sending is neces¬ sary, the speed of sending letters and characters is constant. Speed is decreased by increasing the time intervals between letters and characters. (1) A dot is made by a short flash of about one-half second duration. (2) A dash is a longer flash of about 1 and one-half seconds duration. (3) The interval between dot and dash is of about one-half second duration. (4) The interval between letters is of about one and one-half seconds duration. 1143°—31-7 188 BASIC FIELD MANUAL (5) The interval between words is of about three seconds duration. b. In order that lamp signals may be read easily it is necessary that the signals be sent slowly. Ten to fifteen characters per minute should be taken as the maximum. Successive letters must be well spaced. In general, two men for each shift are necessary to operate a lamp station. At the sending station one man dictates the message letter by letter. The operator watches the receiving station and sends the message. At the receiving station one man receives the message and calls it off letter by letter to his assistant, who writes it down. c. To call a station its call sign should be sent several times, and at intervals the station calling should signal its own call sign. As soon as a station observes that it is being called it will answer by prearranged pyrotechnics or some means other than by lamp or flag. The message is then transmitted and the receiving station acknowledges receipt. d. A message will consist of the following: (1) The call, which consists of the call sign of the called sta¬ tion, the procedure sign “from” (V), and the call sign of the calling station. (2) The body of the message. e. The following is an example of a message: Station A has just received from its message center a message already encoded to be sent to Station C. The text of the message is KEAL LOGW WYNF YTTU. Station A would first “call up” Station C. After Station C has answered, Station A would send as follows: CC (call sign of receiving station). V (from). DD (call sign of sending station). KEAL LOGW WYNF YTTU. AR (ending sign). • 166. Methods of providing improvised equipment.— a. In permanent and semipermanent stations an arrangement for holding the lamp in a fixed position, directed at the receiving station, should be installed. In addition a wooden tube, taper¬ ing down toward the outer end and being 6 to 9 feet long and approximately the size of the lamp at the inner end, should be constructed and also permanently aligned on the receiving sta¬ tion. This reduces the diffusion of the rays of the lamp and BASIC FIELD MANUAL 189 also minimizes the possibility of the signals being read where not intended. An additional advantage is the constant direction of the lamp and readiness for operation. b. In the event the lamp system is put out of commission, any possible means of establishing flash communication may be used. The ordinary pocket flashlight may serve this purpose. Section II FLAGS 167. Care. —Signal flags should be examined at the close of drill or practice and repairs made to any rent or loose ties dis¬ covered. Flags, when soiled, should be thoroughly washed and dried in the sun. Signals made with clean flags are much more easily read than those made with dirty flags. 168. Use.—a. In selecting a flag signal station a point should be chosen which is in view of the station with which communica¬ tion is desired. Stations should be located where they are most difficult of discovery by the enemy. Great care should be taken in transmitting cipher or code messages and, when practicable, they should be repeated. The flagman should stand in such a position that the background will be of the same color for every position of the flag. The color of the flag must contrast as strongly as possible with that of the background. b. The azimuth of all stations with which another station has to work will be carefully noted and recorded. In addition, guide lines may be established by driving two stakes into the ground relatively close to each other so that an imaginary line through the stakes will strike the distant station. Each set of stakes should be tagged with the name of the station on which aligned. c. Each station should be provided with a list of “calls” of stations with which communication is expected. d. Whenever a call is observed, the called station will at once respond, making the signal for “acknowledge.” The calling station will at intervals, when calling, give its own call. e. When a station has sent all messages on hand, the signal “end of message” or “finish” will be made. /. If a signal station should ask another to move its station either to the right or left, so that its signals will be more distinct, a signalman at each station will hold a flag above his head. The station asking for the change will lower its flag 190 BASIC FIELD MANUAL immediately when the distant station arrives at a position with a good background. <7. Signalmen should examine from time to time every promi¬ nent point within signaling distance to see if communication is being attempted therefrom. Attempts to attract the attention of a station, in order to be successful, must be persistent. h. When not in immediate contact with the enemy, stations may communicate in any direction and may furnish a readily available means of communication. i. When in immediate contact with the enemy, communication by means of flags will generally be employed only from front to rear or perhaps laterally. Acknowledgment from rear to front will be made by pyrotechnic signal or some means other than by lamp or flag. 169. Training. —Steps to be followed in training flag signal¬ men are as follows: a. Learning the general service code as applied to flag signal¬ ing. This is accomplished by practice with wands or sticks of light wood about 18 inches long and one-half inch in diameter. The wand is held loosely between the thumb and forefinger and waved rapidly to the right or left to indicate the letters of the alphabet. Signals made are intended only to be read at very short distances. The effectiveness of such wands may be in¬ creased by tying a handkerchief or cloth near the outward end. b. Outside practice in transmission and reception of signals over distances which permit of verbal communication between stations or groups. c. The transmission and reception of messages between sta¬ tions or groups separated beyond speaking distance. d. Instruction in the use of the compass and map reading. e. The establishment, operation, and maintenance of flag stations under assumed tactical situations. 170. Procedure signs.— Procedure signs are the same as for lamp signaling with the exception of those listed below: Wigwag Semaphore Find nf word Front.. ... Interval. Chop, chop (made twice). Chop, chop (made 3 times). MR. ML. MU. MD. End of sentence. End of message . .. A/Tiwp. t.n vnnr ripht. Front, front.._ __ Front, front, front_ MR _ A/Tnve t.n vnnr left. ML_ Move nn MU_ TVTnvp. down MD_ BASIC FIELD MANUAL 191 171. Semaphore code. —The code used with the 2-arm semaphore is shown hr Figure 83. The “chop chop” signal is made by extending both arms to the right horizontally, and then moving the flags up and down with a cutting motion. As the flag in the right hand is moved up, that in the left hand is moved down. 172. Wigwag motions and position. —For wigwag flag signaling there are three motions and one position. Position is with the flag held vertically, the signalman facing directly tow T ard 1 p F M 6 k 4 p 1 <> w< > u I t p "i B M 2 G .< 4 ' HT=j! Q I 3 u , j INTERVAL w 0 X r i r w at f l^l 9 n n iv x X J c^i < Nt =, 0 V I Figure 83. —The 2-arm semaphore code the station with which it is desired to communicate. The first motion (the dot) is to the right of the sender, and will embrace an arc of 90°, starting with the vertical and returning to it, and will be made in a plane at right angles to an imaginary line connecting the two stations. The second motion (the dash) is a similar motion to the left of the sender. The third motion (front) is downward directly in front of the sender, and instantly returned upward to the first position. Front is used to indicate an interval. 173. Station operation. — a. A flag station is normally manned by two men. One man records incoming messages and 192 BASIC FIELD MANUAL calls off the words of a message in transmission. A second man manipulates the sending equipment and reads and calls off incoming messages for the recorder. b. The call letters prescribed for lamp stations are the same as for flag stations. Transmission procedure by flags and by lamps is identical so far as the form of the message is concerned. 174. Methods of providing improvised equipment.— Strips of white or colored cloth tied toward the outward end of sticks of wood or bayonets will serve for flag communication. Section III PYROTECHNICS 175. Description. — a. The pyrotechnic devices now used by the Army consist of rockets, Very pistol, position lights, air¬ plane flares and special dischargers. b. The signal rocket at the present time is probably the best known of military pyrotechnic devices. It is complete in itself and in its entirety does not weigh more than 2pounds. The signal rocket consists of a case-or carton approximately 12 inches long by 1*4 inches inside diameter. Attached to the rocket body is a small cylinder or carton containing a composition which is ignited at the same time as that of the propelling charge. This device is called a smoke tracer, and leaves behind it a trail of smoke w r hich aids the observer in determining from wdiat point the rocket made its flight. Attached to the rocket body by means of a socket is a stick % inch square and 6 feet long which serves as a balance for the upward flight of the rocket. The pro¬ pelling charge is of such composition and of such weight that it will force the rocket upward in its flight to a height of from 800 to 1,000 feet. The rocket is so designed that when the propelling charge has completed its work and the rocket has reached its height a blowing charge is ignited which expels the garniture from the head, throwing the parachute and signal to a distance of about 40 feet. During this flight the parachute frees itself and opens out holding the signal suspended. The signals are so designed that they are ignited by the blowing or expelling charge. Signal rockets may contain either a single star supported by a parachute or a single star or cluster of stars unsupported. These signals may be in three colors- white, green, and red. In addition there are special day signals of a red or yellow smoke or flag supported by a parachute. BASIC FIELD MANUAL 193 Labels giving directions for the firing of the rockets are pasted on the waterproof rocket wrapper, on the rocket head, and at the ignition end of the rocket. c. The Very pistol cartridge is a pyrotechnic cartridge which is fired from a specially designed pistol. The cartridge, which is similar to a shotgun cartridge, holds the signal which is propelled about 200 feet, burning from 6 to 8 seconds, the ignition taking place about 50 feet from the muzzle of the pistol. The Very pistol cartridge may have either red or white single stars, red caterpillar with parachute, red star cluster, or yellow smoke with parachute. d. V. B. cartridges are pyrotechnic devices which are fired from a discharger (tromblom) attached to the muzzle of a rifle. They are used for signaling purposes and are usually fired to a height of about 500 feet. The charge, which is projected into the air, consists of small briquettes which burn with a brilliant light and produce a meteor effect, or colored lights suspended from a para¬ chute which can be easily distinguished from the meteor effect. The V. B. cartridge is shot out by means of the explosion of a blank cartridge in the rifle. The discharger is portable and may be attached to any standard type of rifle. The blank cartridge used for the V. B. cartridge is supplied with a reduced charge. Each V. B. cartridge has a blank rifle cartridge attached to it so that men in the field are supplied with a special cartridge to fire it. e. Position lights are made to burn with a white, red, or green illumination. Such pyrotechnic devices are relatively small, can be easily transported, and are efficient for illuminating purposes as well as for signaling. The position light is cylindrical in form, 2% inches high by 1% inches inside diameter, and is loaded with an illuminating composition. Ignition is accomplished by means of the striker disk and the prime blob. /. Airplane flares, wing-tip flares, and wind-direction signals are illuminating devices and aids to navigation. g. Pyrotechnic devices which lend themselves most readily to the use of small cavalry units are Very pistol cartridges and posi¬ tion lights. When their use is probable, position lights may be carried in saddle bags. 176. Care.— a. Signal and lighting fireworks must not be mingled with ammunition or other fireworks. Signal fireworks (red or green) are loaded with compositions "which are liable to explode in certain cases, and hence these should be separated from other signal or lighting fireworks whenever this is feasible. 194 BASIC FIELD MANUAL • b. Since Very pistol cartridges and V. B. cartridges are dis¬ charged by percussion, due caution will be exercised to prevent accidental discharge. Boxes will be placed flat, top side up, and protected against moisture. In storehouses and depots fireworks will, as far as possible, be classed by lots manufactured about the same time; the oldest will be distributed first. Fireworks whose serviceability is uncertain will be tested. 177. Use.— a. Pyrotechnic signals are important for acknowl¬ edging lamp signals and, to a more limited extent, flag signals. b. In order to insure transmission through fog, smoke, and dust it may be necessary to establish a chain or series of stations equipped with pyrotechnic devices. c. The primary use of position lights is to mark the location of the front line upon request by aerial observers. The grouping of position lights by ones, twos, or threes might be used to convey information. They should be distributed evenly along the front line and never lighted except on request by the airplane. It is generally possible to screen the lights from enemy view by placing them at the bottom of a shell hole or behind a screen of some sort. Position lights are not projected and consequently have a limited range of visibility in any but a vertical direction. d. Due to the rather high recoil of the V. B. cartridge, the butt of the rifle is placed on the ground before discharge. The desired angle which will project the light either for signaling or for illuminating is obtained by inclining the rifle. e. Due to the danger involved, rockets should be fired from a tube or trough whose position is nearly vertical. 178. Training. —The steps to be followed in training pyro¬ technic men are as follows: a. The firing and reading of signals. b. The employment and tactical use of pyrotechnic signals c. Care, handling, and distribution of fireworks. d. Instruction in the use of the compass and in map reading. e. The transmission and reception of messages. /. The establishment, operation, and maintenance of pyro¬ technic stations under assumed tactical situations. 179. Pyrotechnic signals.— a. The following are the stand¬ ard pyrotechnic signals: (1) Ground service—;projected signals. —Single star, parachute, red- single star, parachute, wdiite; caterpillar, parachute, red; star cluster, red; yellow smoke, parachute; phosphorus smoke; message signal. BASIC FIELD MANUAL 195 (2) Air service—projected signals .—Single star, parachute green; caterpillar, parachute, white; caterpillar, parachute, green; star cluster, white; star cluster, green; airplane flare, parachute,, white; wind direction signal; orb; streamer; yellow smoke, para¬ chute; phosphorus smoke; message signal. (3) Ground service and air service .—Position lights, red; position lights, white; position lights, green; wing tip flare. b. A sample pyrotechnic code is as follows: (1) For use by the liaison airplane. I am the airplane of the 4th Division. Understood__ Where are you?_ (2) For use by the Infantry. Request for artillery fire in prep¬ aration for our attack. We are ready to attack_ We are going to advance; length¬ en fire. Understood or am ready_ Request for artillery barrage_ Our front line position, all is going well. Our front line position, we are held up. Single star parachute, green. Caterpillar, parachute, white. Star cluster, white. Single star parachute, white. Yellow smoke rocket. Caterpillar parachute, red. Star cluster, red. 1 red star. Position lights, white. Position lights, red. c. Additional pyrotechnic signals which may be used: Request for grenades_ (To be provided.) Field artillery fire is falling short_ Do. Heavy artillery fire is falling short_ Do. Objective reached__ Do. Repeat message (or signal) or not under- Do. stood. We are stopped before reaching objective. _ Do. Section IV PANELS 180. Reference. —For description of panels and general in¬ formation on panel signaling see chapter 7, Basic Field Manual, Vol. VIII. The panel codes are published on cards and issued to using organizations. (See par. 204 d.) 196 BASIC FIELD MANUAL 181. Care.—Panels should be examined before and after use and repairs made to any rent or loose grommets. When soiled, panels should be thoroughly washed and dried in the sun. Signals made with clean panels are much more easily read than those made with dirty panels. Panels which are damp or wet should be thoroughly dried before folding for carrying. This prevents deterioration and also lessens the weight of the panels. 182. Use.—Signals made with identification panels should appear as pictured to the observer in rear of them and facing the enemy. In view of the fact that enemy airplanes can also locate command posts when identification panels are displayed, they are removed when not in actual use. To facilitate identification and location of command posts and headquarters, it is necessary for a friendly airplane observer to have noted on his map the location of the headquarters or command post with which he works and to call for identification as he needs it. 183. Training. —The steps to be followed in training panel men are— a. The memorizing of the designs for panel numerals, special signals, and identification panel groups of their own headquarters. b. The displaying of panel numerals, special signals, and identification panel groups on the ground by means of panels. c. Simulated practice in sending messages or signals to the airplane. d. Location of panel ground and actual transmissions to an observer in an airplane. CHAPTER 5 DROPPED AND PICK-UP AIRPLANE MESSAGES Section I. Dropped messages... II. Pick-up of messages Paragraphs 184-187 188-193 Section I DROPPED MESSAGES 184. Use. Dropped messages are normally received by units down to and including the battalion, but in emergency or by preanangement messages may be dropped to any unit, detach¬ ment, or individual. During heavy shelling by friendly bat¬ teries,. except in emergencies, dropped messages are not sent to units in front of the light artillery positions. 185. Dropping grounds. —Message-dropping grounds or panel-display grounds are located near the radio station. Unit panels are displayed on these grounds when there is a message for the airplane or when the airplane calls for panels. A droj> ping ground should be an open space removed from high trees, bodies of water, and weeds. A panel-display ground must be so located if possible that the panels can be seen from airplanes at wide angles from the vertical. 186. Procedure in dropping a message. —When an air¬ plane desires to drop a message for a particular unit, it makes a prearranged wing or pyrotechnic signal, meaning “attention ,” over the unit for which the message is intended. The unit display s its identification panel and makes a panel or pvrotechnic signal meaning “understood.” The message is then dropped by the airplane in the nearest clear space to the point where the ground troops made the signal. On the approach of a friendly airplane, all ground troops observe the airplane for a dropped message. Whether or not prearranged signals are made from the airplane, the message will be picked up by the nearest troops and taken at once to the unit message center or to the com¬ manding officer. 197 198 BASIC FIELD MANUAL 187. Equipment. — a. The message bag and streamer are improvised by Air Corps personnel, the bag being made of heavy cloth. It is 7 Yi inches long by 4% inches wide. In order to mark for ground troops the line of descent of the bag and its location on the ground, it has two 72-inch streamers, one yellow and one white. Two ounces of sand are placed in one end so that the bag will fall straight to the ground. The bag also contains one- fourth ounce of kapok to keep it afloat if dropped in water. A draw string or other suitable means is provided for securely fastening the message compartment. Printed on the bag are the words, “ Mail or Deliver to the Nearest U. S. Air Corps Troops.” b. Metal tubes are provided by the Air Corps for dropping maps or photographs; these tubes, made of duralumin, are 9% inches long and 1% inches in diameter. A chrome-yellow streamer 30 by 3% inches is attached. The tube is closed by a rubber stopper. Sectiont II PICK-UP OF MESSAGES 188. Use. —The method of pick-up described herein is used when it is desired to pick up messages or other light packages from localities where landing fields are not available. 189. Pick-up field. —An open field is selected 300 yards or more in length, with clear approaches up and down wind—i. e., there should be no obstacle in the line of flight of the airplane w T hich would keep it from flying close to the ground. The direc¬ tion of the wind must be carefully noted as the line of flight of the airplane will be into (against) the wind. The degree of suc¬ cess obtained will depend largely upon the selection of the field and the careful layout of the apparatus. 190. Equipment. — a. The materials required are— Two light poles, 12 to 14 feet long and about 2 inches In diameter, or two rifles with bayonets attached. Two 20-penny nails, with heads filed off, or two pieces of stiff wire. (No nails or wire are needed if rifles and bayonets are used.) One hundred feet of cord about three thirty-seconds inch in diameter or any flexible material of equal strength and weight. Two code-and-distinguishing panels (12 by 2/3 feet each). BASIC FIELD MANUAL 199 Two streamers approximately 16 inches by 3 feet, preferably white. One message bag. b. The issue of standard equipment for message pick-up is not contemplated, it being assumed that the items listed, or satisfactory substitutes therefor, are either supplied the unit for other purposes or can be improvised locally. 191. Preparation and arrangement of equipment. — a. The equipment is prepared as follows: (1) A 20-penny nail with head filed off is partly driven into each pole about 6 inches from the top. It is important that the nails be carefully smoothed off so that the string can not foul. If rifles with bayonets attached are used in lieu of poles, the hilt of the bayonet is used in the same manner as in prescribed below for the nail. (2) A white streamer is tied around or otherwise fastened to the top of each pole so that it hangs down the side of the pole opposite the nail. These streamers mark the tops of the poles for the pilot. (3) The cord is then tied into a continuous loop and the mes¬ sage bag is attached to one side thereof. Each message bag should weigh about 1 pound. If the weight of the bag and message is less than 1 pound, some foreign substance of small volume should be added to make the weight about 1 pound. This weight, however, should not be exceeded. b. Figure 84 illustrates the arrangement of the equipment for pick-up work. The poles are placed about 40 to 50 feet apart and are held upright in such a manner that the nails point into (against) the wind. The streamers on the poles assist in placing them in the proper position with respect to the wind. The cord loop is then so placed over the nails that the message bag will be equidistant from the poles and hang clear of the ground, the com¬ plete cord loop thus forming a triangle whose plane is perpendicu¬ lar to the direction of the wind and whose apex, to which the message bag is attached, points to the ground. The taut hori¬ zontal portion of the cord is that by which the pick-up is to be accomplished. c. The panels are now laid out, one extending from the base of each pole in the direction toward which the wind is blowing. These panels assist in marking the position for the pilot. 192. Procedure in picking up the message.— a. When all is ready, the airplane is signaled by panel to pick up the message. 200 BASIC FIELD MANUAL The airplane will then approach against the wind with about 50 feet of the radio antenna (or other weighted line) trailing, and will pick up the cord loop and message by fouling the top of the cord loop by the antenna or line. The antenna or line is then hauled into the airplane and the message removed. The ground detail immediately takes up the “pick-up message” panel signal. b. More than one attempt may be necessary, however, before the message is successfully picked up. If a pick-up attempt is unsuccessful, the ground detail will prepare for another trial. Figure 84.—Arrangement of equipment for message pick-up If repair or rearrangement of equipment is necessary, the panel signal for “pick-up message” will be removed until all is ready for the next attempt. c. All members of the ground detail should watch the approach¬ ing airplane, and especially the weight on the end of the antenna or line. Since it is difficult for the pilot to exactly control the path of the line and weight, the ground men should be alert to avoid being struck by the weight and also to prevent the fouling of the line with the poles. BASIC FIELD MANUAL 201 193. Training. —In preparing yearly training programs, provision should be made where practicable for training in mes¬ sage pick-up. In order to impress on all personnel the possibility of the use of this means of communication without special equip¬ ment, the ground troops should be required to entirely improvise the equipment required, utilizing for the purpose organizational equipment, personal equipment and clothing, or articles obtained locally. For example, two small trees might be used for poles, stubs or branches being utilized in lieu of nails or wire, under¬ shirts might serve as panels, handkerchiefs as streamers, an old rag for message bag, and unraveled shelter-tent ropes for cord. >. CHAPTER 6 MESSAGE CENTER x ax agi apno Section I. General_ 194-199 II. Military cryptography_ 200-206 III. Description and use of the cipher device, type M-94_ 207—214 IV. Procedure in divisions and higher units-- 215-221 V. Procedure in brigades and lower units_ 222-225 VI. Related procedures_ 226-232 VII. Pigeons at message centers_ 233-239 Section I GENERAL 194. Reference. —For the classification of messages according to necessity of speed in their transmission, see paragraph 122, and chapter 8, Basic Field Manual, Volume VIII. 195. Definition. —The term “message” as used in this chap¬ ter includes all instructions, reports, orders (either crypto- graphed or in clear text), documents, photographs, or maps transmitted by agencies of signal communication. 196. The message center defined. — a. The message center is the agency at each headquarters or command post charged with the receipt, transmission, and delivery of all messages except the following: (1) Messages transmitted from the originator to the addressee by telephone or personal agency. (2) Messages handled by the Military or Civilian Postal Service. (3) Messages passing directly from the originator to a signal communication agency (as a radio station) for immediate trans¬ mission, in cases authorized by the commander. b. The unit message center exists primarily for service to the commander and his staff and furnishes this service by— (1) Providing a fixed locality to which messengers or messages may be directed. (2) Coordinating the use of various agencies of signal communication. 202 BASIC FIELD MANUAL 203 (3) Keeping temporary but reliable records to insure the prompt and accurate handling of all messages passing through the message center. c. The message center is not organized or equipped to perform stenographic or clerical work pertaining to the different sections of the staff, nor to prepare additional copies of incoming messages for multiple distribution. 197. Principles of operation. — a. During active operations message center service is continuous, and is effected as follows: (1) Message centers may function during the march to afford communication between columns, communication within the column, and communication with aerial or ground reconnaissance troops. (2) A message center is established at each echelon of the headquarters. When a headquarters echelon moves, the mes¬ sage center opens at the new location prior to the closing of the message center at the former location. b. The message center and the routes leading thereto are marked with appropriate signs. On the march the position of the message center in column is made known to all concerned. c. In coordinating the use of the various agencies of signal communication, the message center employs the most suitable means available for the transmission of any message. To this end the message center must be kept informed as to the availa¬ bility of all agencies. The considerations governing the means of transmission to be employed are— (1) Messages to go only a very short distance should ordinarily be sent by messenger. (2) Short messages going a comparatively long distance should be sent by some electrical means. (3) Very long messages should usually be sent by messenger. (4) When necessary to send long messages by radio, they should be broken up into several transmissions. (5) If the importance of the message so warrants, it may be sent by two or more means. (6) Urgent and priority messages are sent by the most rapid means available. 204 BASIC FIELD MANUAL 198. Abbreviations. —In designating the agency by which messages may be sent the following abbreviations, in addition to those listed in AR 859-150, are authorized: Tp=Telephone. Tg=Telegraph. Msgr= Messenger. Rad = Radio. Vis=Visual. Msg Cen = Message center. Msg = Message. Pgn = Pigeon. Run = Runner. Mtclt= Motorcyclist. Belt = Bicyclist. Mtd= Mounted. Sp Msgr=Special messenger. 199. Prescribed procedures. —In keeping records of traffic, the message center follows the simplest procedure consistent with the prompt and accurate handling of messages. A simpler pro¬ cedure can be followed in small units than in large ones. For this reason, two methods of message center procedure are author¬ ized by this manual. The first procedure (Sec. IV) is applicable to divisions and higher units, while the second (Sec. V) is usually employed by brigades and lower units. However, nothing in this manual will be construed to restrict brigades and lower units from using the procedure prescribed in Section IV, if found advisable. Section II MILITARY CRYPTOGRAPHY 200. Use of cryptograms. —All messages to be transmitted by radio or other means, when danger of hostile interception exists, are cryptographed, except in the following cases: a. The commander may direct that a message be transmitted in clear text when in his opinion the information contained is of no value to the enemy, or -when the urgency of the message out¬ weighs its value to the enemy. Such messages will be marked “Send in clear,” over the commander’s signature. b. Commanders may authorize the normal transmission of artillery fire-control messages in clear. c. All crjrptographing and decryptographing of messages at a headquarters are performed in the message center, except as authorized in paragraph 223, unless the message requires a code or cipher not in the possession of the message center. The mes¬ sage center is provided with the authorized codes, cipher devices, and keys. d. If it becomes necessary to modify the wording of a message to facilitate cryptographing, the modified text will be submitted to the originator for approval before transmission. BASIC FIELD MANUAL 205 201. Definitions. —A knowledge of the following terms is essential for all personnel handling code and cipher communica¬ tions. a. Plain text, or clear text, or plain anguage is the text of a writing which, on its face, conveys an intelligible meaning in a known language. b. Secret text or secret language is the text of a writing which, on its face, conveys no intelligible meaning in any known lan¬ guage. The secret text of a message constitutes a cryptogram. c. Cryptography is the science which embraces all the methods and devices whereby plain text may be converted into secret text. d. Cryptograms are of three fairly distinct t}^pes as follows: (1) Cipher. (a) A cryptogram in cipher is one which has been produced by taking the individual letters of the plain text as- units and applying to them either or both of two cryptographic processes known as transposition and substitution, explained below. The resulting secret text is called cipher text, and the operation of producing it is called enciphering; the reverse opera¬ tion, that of reproducing the plain text from the cipher text by a direct reversal of the steps involved in its enciphering is called deciphering. (b) The basis of every cipher system is an agreement between correspondents covering the general method and the steps to be followed in crypto- graphing. That portion of the agreement which specifically controls the steps under the general method is termed the key. The key is usually of a variable nature, changeable at the will of the cor¬ respondents. Normally it consists of an easily remembered word, phrase, or sentence; or of a number or series of numbers derivable from a word, phrase, or sentence. (c) The crytographic process known as transposition con¬ sists in rearranging the letters constituting the plain text (rarely syllables or whole words) so that the resultant text becomes unintelligible. The let¬ ters undergo no change in identity; only their rela¬ tive order is altered. A cryptogram which has been produced in this way is termed a “transposition cipher.” 206 BASIC FIELD MANUAL ( d ) Substitution cipher .—The cryptographic process known as substitution consists in replacing the letters con¬ stituting plain text by other letters, figures, symbols, or the like. Here the letters undergo a change in identity, without a change in their relative order. A cryptogram which has been produced in this way is termed a “ substitution cipher ” (e) Combined cipher .—When both of these processes have been applied in producing a cryptogram the latter is termed a combined “ substitution-transposition cipher ” (2) Code. (a) A cryptogram in code is one which has been produced by taking whole sentences, phrases, words, letters, or numbers of plain text as units and replacing them by arbitrary groups of symbols given as their equivalents in a code book. The resulting secret text is called code text , and the operation of pro¬ ducing it is called encoding; the reverse operation, that of reproducing the plain text from the code text by reference to the code book, is called de¬ coding. A “one-part code” consists of only one section, which serves for either encoding or de¬ coding. A “2-part code” consists of two sections, one section arranged to facilitate encoding and the other to facilitate decoding. A 1-part code is very much less secret than a 2-part code. (b) Code groups or code words are arbitral groups of sym¬ bols constituting code text. They usually consist of letters or figures or rarely of both letters and figures. (3) Enciphered code .—A cryptogram in enciphered code is one which has been produced by first encoding the plain text and then enciphering the code text. e. To cryptograph a message is to convert its plain text into secret text. This is a convenient term to use in referring to the processes involved without indicating or specifying whether they are methods of enciphering or encoding. _ t /. To decryptograph a message is to reconvert its secret text into plain text by a direct reversal of the operations involved in its cryptographing. This is a convenient term to use in referring to the processes involved without indicating whether the crypto- BASIC FIELD MANUAL 207 gram is in cipher, in code, or in enciphered code. Thus, just as enciphering and encoding are forms of cryptographing , so de¬ ciphering and decoding are forms of decryptographing . g. Cryptanalysis is the name applied to the steps and processes involved in converting cryptograms (usually of hostile origin) into plain text by means other than those normally employed in decryptographing messages of friendly origin. 202. Safety afforded by cryptography. —Codes and ciphers are used in military communications for either or both of two purposes—condensing messages and maintaining secret, except from the addressee, the contents of messages. Unless secrecy is accomplished with certainty, all of the additional time, labor, and danger of error involved in cryptographic messages is wasted; moreover, the correspondents may be lulled into a false sense of security in the belief that their messages are secret, when, in fact, the enemy may have cryptanalyzed them and taken action ac¬ cordingly. With the increased use of radio, as well as other means of electrical communication, the safeguarding of codes and ciphers has assumed a paramount importance. In general it may be stated that no cryptographic system suitable for a voluminous official correspondence is absolutely proof against the organized, cooperative efforts of a large and well-trained staff of cryptanalysts. Practically every cipher system that has ever been employed for military purposes has been solved, and prac¬ tically any code book can be reconstructed by analysis, given a sufficient number of cryptograms and the personnel and time necessary to accomplish it. 203. Comparison of codes and ciphers. — a. Each of these two general methods of secret communication is needed in the military service. A cipher machine meeting all the requirements of practicability and secrecy has not yet been produced. The principal factors to be taken into account in comparing code and cipher methods as systems of secret communication are— (1) Simplicity, rapidity, practicability. (2) Secrecy. (3) Accuracy. (4) Economy. h. In general, it may be said that code is a more rapid and more simple method of secret communication than is cipher. The processes of enciphering and deciphering require very close mental attention to avoid errors, and are usually much slower than those of encoding and decoding, which more nearly ap- 208 BASIC FIELD MANUAL proach automatic processes and thus require less concentrated mental effort. This is of greatest importance in the combat zone. There are some very small cipher devices which tend to reduce the mental strain to a minimum, but in general the cryptograms they yield are not as secret as those produced by a good code, especially when many messages are available for interception by the enemy. c. Code systems are, on the whole, more secret than cipher systems, depending upon— (1) The type of code. A 2-part code is more secret than a 1-part. (2) The extent of its vocabulary or contents. (3) The extent to which the code is used; that is, the number of messages transmitted. d. Furthermore, the solution of one message does not as a rule entail the immediate breakdown of the whole system, with the consequent solution of all other messages in the same key, as is the case in ciphers. On the other hand, in the case of code it is absolutely necessary to guard at all times the code book, so that it does not fall into the hands of the enemy. Actual possession is not always necessary, for a single opportunity to copy or memorize certain portions is sufficient to compromise the whole code. e. On the whole, it may be said that code systems are less accurate than cipher systems and are more subject to the neces¬ sity for repetition of messages. This is because a mistake in one or two code groups may obscure, alter, or render unintelli¬ gible the meaning of a whole message, whereas, in the case of ciphers, the meaning of a few letters which are in error may be supplied by the context. /. Since code text is usually shorter than the equivalent plain text, the latter is more economical to handle than cipher. This is of great importance where the amount of signal traffic is heavy. On the other hand, for the purpose of maintaining secrecy in military communication, codes of the 2-part type must be changed rather frequently. This necessitates repeated processes of preparation, printing, and distribution, all of which take much time and labor. 204. Authorized military codes. —Among others, the fol¬ lowing codes are authorized for general use in the military service: a. War Department Telegraph Code .—This code is a nonsecret code primarily intended for economy. It furnishes no security BASIC FIELD MANUAL 209 from code experts, and should never be used for encoding secret messages. It is issued to all those who are required to handle any considerable volume of business by telegraph, radio, or cable. b. Army Field Code. —This code is issued to message centers of divisions and higher tactical units up to and including general headquarters. It is confidential. c. Division Field Code. —This code is issued to message centers of divisions and all lower tactical units down to and including the battalion, and in peace time for training purposes it may be issued down to companies. It is confidential. d. Aerial Observation Codes and Panels. —These codes are pre¬ pared by the War Department or the headquarters of the field forces and are issued to all units that engage in communication between ground and air. Blank groups are left in both, for assignment of special meanings by local commanders, to meet. special situations. There are two parts: (1) The Fire-Control Code is fixed and nonconfidential and is used in adjustment of fire. (2) The Air-Ground Liaison Code is confidential and is em¬ ployed in general observation and reconnaissance. In emergen¬ cies it may also be used in the absence of other cryptographic means for communication between forward ground stations. It is revised frequently, for purposes of secrecy, by rearrangement of code groups and their meanings. e. Special codes. —Such codes as address and signature codes, telephone codes for organizations and officers, geographic, meteorological, and supply catalogue codes, as well as appendices to the various codes listed above, will be published from time to time. 205. Authorized military ciphers. —Among others, the fol¬ lowing ciphers are authorized for use in the military service: a. Cipher Device, Type M-94 •—This cipher is explained in Section III. It is normally used for messages, the origin or destination of which is forward of battalion headquarters. b. Printing Telegraph Cipher System. —This is a cipher system operated in connection with printing or automatic telegraph machines, and is used only between the larger headquarters where traffic is very great. 206. Rules for use of codes and ciphers. —The following general rules govern the use of codes and ciphers: a. The instructions contained in each code book or furnished with each cipher system must be carefully studied and thoroughly understood before the code or cipher is used. 210 BASIC FIELD MANUAL b. Care should be exercised to prevent the loss or compromise of a code book or cipher key. If a code book is lost or possibly compromised, the fact should be reported promptly to higher headquarters. c. Except in emergency, no code or cipher which has not been approved by higher authority should be employed within any unit. d. Care should be exercised that only one edition of a code of a particular class, or only one cipher key is being used within a unit at one time. When a code is replaced by a new code or a new edition, the replaced code will be destroyed by burning, unless otherwise ordered. e. Cryptographic messages should be short and concise. Long messages facilitate the solution by the enemy. /. Never repeat a message in a code or cipher other than the one in which it was originally sent. If the enemy has already solved one of the codes or cipher keys used, he will translate the message by that code or cipher key and will thus be given clues to the solution of the other code or cipher key. g. Never cryptograph a message which has been sent pre¬ viously in clear, and never send a message in clear w'hich has been sent previously as a cryptogram. If the enemy compares the cryptographic message with the clear message he will be able to break into the code and solve other messages, or, in the case of ciphers, he will have the key for the solution of all other messages. h. Never mix secret and clear text in the same message. This applies also to abbreviations and signs of punctuation, which are equivalent to clear text. If clear text of any kind whatever is left in the message, the enemy can more easily discover the meaning of the secret text. If cryptographed at all the entire message must be cryptographed. i. A decryptographed message never should be filed with the clear message. If it is desired to keep the two attached for any purpose, the clear copy should be paraphrased. j. Capital letters should be employed throughout in writing cryptograms in order to avoid errors. In the case of code, the grouping of the letters of the code text corresponds to the length of the code groups as given by the book; in the case of cipher, the text is written and transmitted in groups of five letters. BASIC FIELD MANUAL 211 Section III DESCRIPTION AND USE OF THE CIPHER DEVICE, TYPE M-94 207. Purpose and distribution. —Cipher device, type M-94, is a cryptographic instrument that is an item of equipment issued by the Signal Corps to all message centers as one of the authorized means for secret communication. It is also an item of equipment possessed by all naval units and stations, including those of the Marine Corps, and can be employed in certain classes of secret intercommunication between the Army and the Navy when specific arrangements therefor have been made by the appropriate commanders. 208. General description. — a. The device is made of alu¬ minum alloy and consists of the following parts: (1) A central shaft, the left end of which terminates with a projecting shoulder, the right end of which is threaded; (2) A set of 25 alphabet disks, on the rim of each of which there is stamped a different, completely disarranged alphabet; (3) A guide-rule disk, consisting of a blank or unlettered disk from which there projects a guide rule; (4) A retaining plate, consisting of a thin disk upon one surface of which is stamped the name and type number of the device; (5) A knurled thumb nut. b. Each disk has a hole at the center suitable for mounting it upon the central shaft, upon which the disk can be revolved forward or backward. The left face of each alphabet disk is provided with a circle of 26 equidistant slots; the right face is cupped, and carries at one point on the inside rim of this cup a small projecting lug. The guide-rule disk also carries such a lug. When the disks are assembled upon the shaft, the lug on each disk engages with one of the slots on the adjacent disk on the right and thus the disks can be held in engagement in any desired relative positions by screwing down the knurled thumb nut against the retaining plate, which is inserted between the last alphabet disk and the nut. c. When the thumb nut and the retaining plate are removed and the alphabet disks are taken off the shaft, it will be noted that each alphabet disk is stamped on its inside or cup surface with an identifying symbol consisting of a number that is above the central hole and a letter that is below it. The numbers run from 1 to 25, inclusive, the letters from B to Z, inclusive. These symbols 212 BASIC FIELD MANUAL are employed to designate the sequence in which the alphabet disks are to be assembled upon the shaft in cryptographing or decryptographing messages, as described in paragraph 210. Either symbol may be used for this purpose (as prearranged) but for the present only the numerical identifying symbols will be so used. 209. Necessity for key and providing for changes there¬ in. — a. Messages cryptographed by the same sequence of alpha¬ bet disks can remain secure against solution by a well-organized and efficient enemy crvptanalytic section for only a relatively short time. It is impossible to state exactly how long, because solution depends upon a number of variable factors; a conserva¬ tive estimate would place the minimum at six hours, the maximum at two or three days. For this reason it is necessary to change the sequence from time to time, and the method for determining or indicating the new sequence must be agreed upon in advance and thoroughly understood by all who are to use the instrument. b. The sequence in which the alphabet disks are assembled upon the shaft constitutes the key in this cipher system. When a change in key is to take place, exactly what the new key will be and the exact moment that it is to supersede the old key will be determined by the proper commander and will be communicated in signal operation instructions (see par. 241). 210. Detailed instructions for setting the device to a predetermined k9y. — a. The method prescribed herein is based upon a key word or key phrase from which the sequence of numbers constituting the key for assembling the alphabet disk can be obtained by following a simple, standardized procedure. The reason for employing such a procedure is that it makes it possible to derive, at will, a relatively long sequence of numbers (which would be difficult to remember) from a word or phrase (which is easy to remember) and thus eliminates the necessity of carrying the key in written form upon the person. It is this basic key word or key phrase which is communicated throughout the command in signal operation instructions. The exact method of deriving the numerical key sequence from the key word or key phrase is given step by step in the following sub- paragraph. b. Assume that the key phrase so communicated is CHINESE LAUNDRY. The following are the detailed steps to be followed in deriving the numerical key sequence: BASIC FIELD MANUAL 213 (1) A set of rows of cross section squares, 25 squares in each row, is prepared. (Prepared sheets of % inch squares are suitable.) (2) In the top row the series of numbers 1, 2, 3-25 are inserted. Thus: 1 2 3 4 5 6 7 8 9 10 11 12 IS 14 15 16 17 18 19 20 21 22 23 24 25 (3) Beginning under the number “1,” the successive letters of of the key phrase are written in the second row of squares, under the successive numbers. Thus: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 C H I N E S E L A U N D R Y (4) The key phrase is extended by repetition until there is a letter under the number “25,” making a key sequence of 25 letters. 1 Thus: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 O H I N E S E L A u N D R Y C H I N E S E L A U N (5) The letters of the key sequence are now to be numbered serially from left to right in accordance with the relative posi¬ tion that each letter occupies in the ordinary alphabet. Since the letter “A” comes first in the ordinary alphabet, and since this letter occurs twice in the illustrative key sequence, the number “1” is written under the first appearance of A in this sequence, and the number “2” is written under its second appearance. Thus: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 O H I N E S E L A U N D R Y C H I N E S E L A U N 1 2 (6) The next letter in the ordinary alphabet is B. The key sequence is carefully examined to see if it contains the letter “B.” Since this letter does not appear in the illustrative key sequence, the latter is examined to see if it contains the letter “C.” This letter occurs twice in the illustrative key sequence 1 If the key consists of a word or phrase containing more than 25 letters, those after the twenty-fifth letter are merely omitted. 214 BASIC FIELD MANUAL and the first C, therefore, is assigned the number “3,” the second C the number “4.” Thus: 1 2345 6 789 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 CHINESELAUNDRYCHINE SELAUN 3 1 4.2 (7) The next letter in the ordinary alphabet is D, which, being present in the key sequence, is assigned the next number, and so on. Thus, the process is continued until each letter has been assigned a number. The work must be done carefully so as not to overlook a single letter. If an error is made in the early stages of the work, it necessitates starting afresh. The operator should be especially careful with letters which immediately follow one another in the ordinary alphabet but are present in the key sequence in reversed order, such as ED, FE, ON, and so on. It is easy to make a mistake in such cases and to assign these let¬ ters numbers in a sequence that is the reverse of what it should be. (8) When the numbering process has been completed, and if the work has been correctly performed, it will be found that every letter of the key sequence has a number under it, and that the greatest number that appears is 25. If this is not the case, it is an immediate signal that an error has been made. It can not, however, be assumed that so long as every letter has a number under it, w T ith the greatest number 25, this is immediate and conclusive proof of accuracy in the work. The operator should invariably check his work; better yet, if two clerks are available each one should derive the numerical key independently and the final results checked by comparison. (9) The key phrase selected as an example in the foregoing description yields the following numerical key: 1 2 3 4 5 6 7 8 9 10 n 12 13 14 15 16 17 18 19 20 21 22 23 24 25 C H I N E S E L A u N D R Y C II I N E S E L A U N 18 19 o jLU 1Z ID D Zl / 14 1 Z6 1 l 0 zu Zo 4 11 lo O ZZ 9 15 24 (10) It is this sequence of numbers which indicates the order in which the successive alphabet disks are to be assembled upon the shaft from left to right. Thus, according to the foregoing key sequence, alphabet disk No. 3 comes first, that is, immediately to the right of the guide-rule disk; alphabet disk No. 10 comes next, and so on. Alphabet disk No. 19 is the last in this particu¬ lar key, and after it has been placed on the shaft, the retaining plate and thumb nut are added and the latter screwed down a BASIC FIELD MANUAL 215 distance sufficient to keep the assembly together and yet permit of revolving individual disks freely upon the shaft. The instru¬ ment is now ready for use in either cryptographing or decrypto¬ graphing messages. 211. Cryptographing a message. —Suppose the following message is to be enciphered with the key derived in paragraph 210: CO 3d INF HAVE JUST REACHED EASTERN EDGE OF WOODS ALONG 552-592 ROAD. WILL REMAIN IN OBSERVA¬ TION. CO 2d BN a. The message is written down on the work sheet underneath the key in lines of 25 letters each. Space is left under each line for the insertion of cipher letters. (For procedure in connection with abbreviations and numbers appearing in the text of mes¬ sages, see par. 212.) Thus: fl 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 CHINE S E L A U iTlTR YCHINE SELAUN 3 10 12 1G 6 21 7 14 1 23 17 5 20 25 4 11 13 18 8 22 9 15 2 24 ~19 COTH I RD INF HAVE JU STREACHED EASTERNE DGEOFWOOD SALONGF I VEFIVE TWODAS II F IVENI N E T W Q R O A D W I LLREMAIN IN OB SERVATIO NCOS ECOND BN b. By revolving the disks upon the shaft, one by one, the first 25 letters of the message are aligned to form a continuous horizontal row of letters reading from left to right along the out¬ side of the cylinder. The guide-rule will be found very con¬ venient in marking the row upon which the letters are being aligned, thus relieving the eyes of unnecessary strain and re¬ ducing the chance of making errors. After all 25 letters have been aligned, the assembly is locked in position so that no disk can become displaced accidentally in further manipulation of 216 BASIC FIELD MANUAL the cylinder. The row of letters is immediately checked to make sure that no displacement has occurred among the first few disks while manipulating the last few. c. The outside of the cylinder now presents a series of 26 rows of letters, of which 24 rows are fully visible, the other two being hidden or partially obscured by the guide-rule. One of the 24 visible rows is the plain-text row that has just been set up, and the other 23 rows are cipher-text rows any one of which may be selected to represent the plain-text row. One of these cipher- text rows is selected at random, and the letters composing this row are written underneath the row of plain-text letters on the work sheet. Thus, supposing the row beginning LYEUJ has been selected, the first cipher line will read as follows: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 c H I N E S E L A U N D R Y C H I N E S E L A U N 3 10 12 16 6 21 7 14 1 23 17 5 20 25 4 11 13 18 8 22 9 15 2 24 19 C 0 T H I R D I N F H A V E J U S T R E A C H E D L Y E U J D J N Y P Q B F Y N E c N H P F A G P G It is not necessary to make any record on the work sheet as to which cipher-text row (above or below the plain-text row) was selected, nor is it necessary to indicate it in any manner whatever in the cipher message. d. The thumb nut is loosened, but not removed from the shaft. The next 25 letters of the message are aligned, the thumb nut screwed down against the retaining plate, the letters in the align¬ ment are checked, and again any one of the 23 visible cipher-text rows, except the one used to encipher the first line, is selected at random for the cipher text. The letters in the row selected are written down under the second line of plain-text letters on the work sheet. Thus, supposing the row' beginning KZBYJ was selected, the work sheet now appears as follows: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 C H I N E S E L A U N D R Y C H I N E s E L A U N 3 10 12 16 6 21 7 14 1 23 17 5 20 25 4 11 13 18 8 22 9 15 2 24 19 C O T H I R D I N F H A V E J U S T R E A C II E D L Y E U J D J N Y P Q B F Y N E c N H P F A G P G E A S T E R N E D G E O F W O O D S A L O N G F I K Z B Y J I A H N S R A N D J M E F S Y R I T S N e. This process is continued in similar manner w'ith the third and fourth lines of the plain-text message. It should never be made a practice to “favor,” i. e., frequently to select a particular BASIC FIELD MANUAL 217 cipher-text row above or below the plain-text row. As irregular a selection as possible should be made, and the selection of the cipher-text row immediately above the plain-text row or imme¬ diately below the lower edge of the guide-rule should be avoided. Supposing these instructions to have been followed and that there has been selected for the cipher-text row representing the third plain-text line of the message the row beginning RAMTF, and for that representing the fourth line, the one beginning PJNSY, the message now stands as follows: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 CHI N E S E L A U N D R Y C H I N E S E L A U N 3 10 12 16 6 21 7 14 1 23 17 5 20 25 4 11 13 18 8 22 9 15 2 24 19 C 0 T H I R D I N F H A V E J U S T R E A C H E 'D L Y E U J D J N Y P Q B F Y N E c N H P F A G P G E A S T E R N E D G E 0 F w 0 0 D S A L 0 N G F I KZ B Y J I A H N S R A N D J M E F S Y R I T S N V E F I V E T W 0 D A S H F I V E N I N E T W 0 R R A MT F 0 M O K E N c S H c s P M X H T E X G M O A D W I L L R E M A I N I N 0 B S E R V A T I 0 P J N S Y V A W U C H Y F H E Y T B G P Y K G M G /. There are left only eight letters to be enciphered, not enough to make a complete row of 25 letters. This, however, makes no difference in procedure; these eight letters are merely aligned and a cipher-text row is selected to represent them. Supposing the row beginning URZGH is selected, the message now stands as follows: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 C II I N E S E L A u N D R Y C H I N E S E L A U N 3 10 12 16 6 21 7 14 1 23 17 5 20 25 4 11 13 18 8 22 9 15 2 24 19 C O T H I R D I N F H A V E J U S T R E A C H E D L Y E U J D J N Y P Q B F Y N E c N H P F A G P G E A S T E R N E D G E O F W O O D S A L O N G F I K Z B Y J I A II N S R A N D J M E F S Y R I T S N V E F I V E T W O D A S H F I V E N I N E T W 0 R R A M T F O M O K E N c S H c S P M X H T E X G M 0 A D W I L L R E M A I N I N 0 B S E R V A T I O P J N S Y V A W U C H Y F H E Y T B G P XT' A K G M G N C O S E C O N D B N U R z G H E J Q S M D 218 BASIC FIELD MANUAL g. The cipher text is now to be copied on the message form, in 5-letter groups. It is as follows: LYEUJ D J N Y P QBFY5 ECNHP FAGPG KZBYJ IAHNS RANDJ MEFSY RITSN RAMTF OMOKE NCSHC SPMXH TEXGM PJNSY VAWUC HYFHE YTBGP YKGMG URZGH EJQSM D h. The last group of the cipher message is, however, not a com¬ plete group of 5 letters. It is made so by adding four X’s. These are not to be cryptographed; they are added merely to com¬ plete the last cipher group. The final message becomes as shown below: LYEUJ DJNYP Q B F Y N ECNHP FAGPG KZBYJ IAHNS RANDJ MEFSY RITSN RAMTF OMOKE NCSHC SPMXH TEXGM PJNSY VAWUC HYFHE YTBGP YKGMG URZGH EJQSM DXXXX The message as it now reads is but one of many different forms in which this same message could appear externally, depending on exactly which of the available cipher-text rows is selected for each line of the encipherment. 212. Cryptographing abbreviations, punctuation signs, and numbers.—a. Authorized abbreviations appearing in the original plain-text message may be enciphered as abbreviations without periods. Examples: Am Tn = AMTN; E. V. Brown Sch=E VBRO WNSCH. b. Normally, the writer of a message spells out the punctuation signs he wishes transmitted, as, for example, STOP, COMMA COLON, etc. If a message contains punctuation signs not so spelled out, the message center chief must indicate whether they are to be omitted or spelled out and transmitted. c. Cardinal and ordinal numbers when spelled out in letters in the original plain-text message are always enciphered exactly as spelled. d. Cardinal numbers when expressed in figures in the original plain-text message must always be spelled out, digit by digit, in cryptographing. Examples: 4=FOUR 40 = FOURZERO (and not FORTY) 400 = FOURZEROZERO (and not FOUR HUNDRED) 455 = FOURFIVEFIVE 450.7-758.3= FOURFIVEZEROPOINTSEVENDASHSEVEN- FIVEEIGHTPOINTEIGHT 2005 = T WOZEROZEROFI VE 12.01 a. m. = ONETWOZEROONEAM 5.15 p. m. = FIVEONEFIVEPM BASIC FIELD MANUAL 219 e. Ordinal numbers above the ordinal number 10th, when expressed in figures followed by “d,” or * ‘ th,” are cryptographed merely as digits spelled out, without adding the “d” or “th.” The omission of the “d” or the “th” will cause no confusion or ambiguity. Examples: 3d Bn = THIRDBN; 7th Pack Tn= SEVENTHPACKTN; 11th Regt = ONEONEREGT; 403d Am Tn=FOURZEROTHREEAMTN. 213. Decryptographing a message.— a. Knowing the key word or key phrase, the numerical key is developed as described under paragraph 210, and the set of alphabet disks is assembled accordingly. The message to be decryptographed is written down in lines of 25 letters, on cross section paper, if available, space being left under each line for the insertion of plain-text letters. Using the cipher message given under paragraph 211 h, it appears under the key in the following form: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 C H 1 N E S E L A u N D R Y C H I N E S E L A U N 3 10 12 16 6 21 7 14 1 23 17 5 20 25 4 11 13 18 8 22 9 15 2 24 19 L Y E IT J D J N Y P Q B F Y N E C N H P F A G P G K Z B Y J I A H N S R A N D J M E F S Y R I T S N R A M T F 0 M 0 K E N C S H C S P M X H T E X G M P J N S Y V A W U C H Y F H E Y T B G P Y K G M G IT R Z G H E J Q S M D b. The first 25 letters of the cryptogram are set up on the device, the letters being aligned in a row from left to right, just above the guide rule. Fixing the disks in this position by screwing down the thumb nut, the whole cylinder is turned slowly, forward or backward, and each row of letters is carefully examined. One of these rows and only one will read intelligibly all the way across from left to right. That is the row which gives the plain text for the first 25 cipher letters. These letters are inserted in their proper place on the work sheet, giving the following: 1143°—31-8 220 BASIC FIELD MANUAL 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 c H 1 N E S E L A U N D R Y C H I N E S E L A U N 3 ib 12 16 6 21 7 14 1 23 17 5 20 25 4 11 13 18 8 22 9 15 2 24 19 L Y E U J D J N Y P Q B F Y N E C N II P F A G P G > X3 3 o ■3 >» JO co ( 2 ) Exceptionally clear_ Clear ___ Dust haze. Haze_ Drizzle.. . ... Light rain White_ Fog .. Moderate rain One-fourth covered_ Wet fog !.. Heavy rain. One-half covered.. _ Fog 2 . ... Hail Three-fourths covered. Wet fog 2 __ Rain and hail__ Covered but with clear Fog 3 __ .. Sleet_ _ spaces. Covered _ Wet fog 3 __ Fog i _ Light snow Halo _ _ Moderate snow Aurora. _. _ Wet fog 4 _. Heavy snow Precipitation with— bo & o £ (3) bfi O t—< o to o Ph (4) bo o P^ (5) O ft ( 6 ) Local storm- bfi g 2 © 03 O 0< ft ◄ (7) be 3 ft ( 8 ) be _g tZ 03 © ft ft c3 •S3 P (9) Wind only. Thunder, lightning, or both. Wind and rain. Thunder, lightning, and rain. Wind and hail. Thunder, lightning, and hail. Wind, rain, and hail. Thunder, lightning, rain, and hail. Tornado. Hurricane. Wet fog x , or fog 1 =most distant object visible 500 to 1,000 yards. Wet fog 2 , or fog 2 = most distant object visible 250 to 500 yards. Wet fog 3 , or fog 3 =most distant object visible 100 to 250 yards. Wet fog 4 , or fog 4 =most distant object visible 0 to 100 yards. In the two figures for present weather the order is as follows: The first figure will be taken from the top of the code table (to indicate the general class of weather) and the second figure from the side (to indicate the subclassification). Thus 61 would be “Light rain with very dense fog.” Code II Code for barometric tendency (b) for last three hours: 0=steady. l=unsteady. 2=rising. 3=falling. 4=falling, then rising. 5=steady, then rising. 6=steady, then falling. 7=falling, then steady. 8=rising, then steady or falling. 9=line squall—sudden rise with marked change in wind and weather. BASIC FIELD MANUAL 275 Code III Code for cloud heights (h): 0=clouds below 150 yards. 1=clouds between 150-300 yards. 2=clouds between 300-500 yards. 3=clouds between 500-750 yards. 4=clouds between 750-1,000 yards. 5=clouds between 1,000-1,500 yards. 6=clouds between 1,500-2,000 yards. 7=clouds between 2,000-2,500 yards. 8=clouds between 2,500-3,000 yards. 9=no low clouds. Code IV Code for form of low (A) and medium or.high (B) cloud: (A) Low cloud: 1 = fracto-cumulus_ 2=mammato-cum ulus. 3=low strato-cumulus. 4=high strato-cumulus 5=nimbus___ 6=cumulus_ 7=cumulo-nimbus_ 8=stratus.__ Average height (yards) 1,500 _ 2,300 _Below 1, 200 -Above 1,200 _ 1,200 _ 1,500 —.. 1,500 _ 700 The above heights indicates the presence will be assumed whenever the message of low clouds but fails to give the height. (B) Medium or high cloud: 1=cirrus. 2=cirro-stratus. 3=cirro-cumulus. 4=false cirrus. 5=thin alto-stratus. G=thick alto-stratus. 7=low alto-cumulus, below 3,500 yards. 8=high alto-cumulus, above 3,500 yards Code V Code for humidity (R): 0=95-100 per cent. 9 = 90-94 per cent. 8=80-89 per cent. 7=70-79 per cent. 6=60-69 per cent. 5=50-59 per cent. 4=40-49 per cent. 3=30-39 per cent. 2=20-29 per cent. 1 = 10-19 per cent. 276 BASIC FIELD MANUAL Code VI Code for state of ground (G): 0=solid (dry or frozen)_ Fit for landing. l=solid (dew)_ Do. 2=solid (light frost)_ Do. 3=solid (heavy frost)_ Do. 4=solid (snow or water in spots; parts of field usable)_ Do. 5=sol id (snow covered)_„_ Do. 6=soft (from rain or thaw)_ Do. 7=soft (from rain or thaw)_ Unfit for landing. 8 = flooded__ Do. 9=solid (snow in deep drifts, or heavy snow, 10 inches or more)_ Do. Code VII Code for visibility (V): 0=0-50 yards; dense fog. 1=50-200 yards; very bad 2=200-500 yards; bad. 3=500-1,000 yards; very poor. 4=1,000-2,000 yards; poor. 5=2,000-4,000 yards; indifferent. 6 = 4,000-10,000 yards; fair. 7 = 10,000-20,000 yards; good. 8=20,000-50,000 yards; very good. , 9=50,000 yards and over; excellent. Code VIII Code for height of upper wind (H): 1=200 yards. 2 = 500 yards. 3 = 1,000 yards. 4 = 1,500 yards. 5=2,000 yards. 6=3,000 yards. 7=4,000 yards. 8=5,000 yards. c. Artillery messages. —(1) There are two meteorological mes¬ sages for artillery, known respectively as “message 2” and “message 3Antiaircraft artillery uses the data contained in message 2. Terrestrial artiller}^ uses the data contained in message 3 except for certain types of guns when fired at high angles of elevation, when it uses the data contained in message 2. The artillery firing tables will indicate which of these two mes¬ sages is appropriate for use with a particular type of gun fired BASIC FIELD MANUAL 277 at a particular angle of elevation. The two artillery messages are similar in form and the same basic data are used in the com¬ putation of both, the only difference being that different weight¬ ing factors are used in computing the messages. (2) Each artillery message consists of a group of letters to designate the sending station, followed by a series of groups of figures, seven figures to each group, with the exception of the first, which includes only five figures. The first group of figures indicates that the message contains meteorological data for artillery, the altitude of the meteorological datum plane and the temperature. Each subsequent group of figures indicates the direction and speed of the ballistic wind and the ballistic density for a specified maximum ordinate. (3) In preparing each message, the station designation (usually repeated) is placed first. (4) The first figure of the first group of numerals is either 2 or 3, indicating that the data contained in the message are for the use of artillery. When the figure 2 is used, it indicates that the data in the message are computed for the use of antiaircraft artillery, or terrestrial artillery firing guns at high angles of elevation. Wdien the figure 3 is used, it indicates that the data in the message are computed for the use of terrestrial artillery except in those cases where terrestrial artillery, firing guns at high angles of elevation, use the data contained in message 2. The next two figures indicate the altitude of the meteorological datum plane to the nearest hundred feet above sea level. The final two figures of this group indicate the temperature at the meteorological datum plane. (5) Each of the subsequent groups of seven figures in both messages indicates the direction and speed of the ballistic wind and the ballistic density for certain maximum ordinates. The first figure in each of these groups shows the height of a maximum ordinate to which data indicated by the other figures in the group apply. The height of the maximum ordinate above the meteorological datum plane (M. D. P.) will be indicated by figures, as follows: Figure 1 Altitude (feet) Figure Altitude (feet) Figure Altitude (feet) 0 0 600 1, 500 3,000 4, 500 5_ 6,000 9,000 12, 000 15, 000 9_ 18,000 24, 000 30, 000 36, 000 1 6 _ 0_ 2_ 7 _ 8 _ 1 _ 2_ 3 4_ 278 BASIC FIELD MANUAL If it is necessary to furnish data for a higher maximum ordinate than 36,000 feet, the above table may be continued by adding 6,000 feet for each increase of 1 in the code number. For in¬ stance, if figure 3 is used the second time to indicate a maximum ordinate, it is understood that the data for the maximum ordinate of 42,000 feet are contained in that group of figures. The repeti¬ tion of numerals in the code to indicate maximum ordinates should not lead to confusion, as the location of the figures in the message indicates their meaning. The data for various maxi¬ mum ordinates are always sent in the order indicated above, namely, the surface data first, followed by the data for 600 feet, 1,500 feet, 3,000 feet, etc. (6) The second and third figures of these groups indicate the direction from which the ballistic wind is blowing, on a basis of 64 points to the circle, starting from the north and measuring clockwise. Thus the figures 16 indicate that the wind is blowing from the east; the figures 32 indicate that the wind is blowing from the south; the figures 48 indicate that the wind is blowing from the west; and the figures 64 indicate that the wind is blowing from the north. (7) The fourth and fifth figures in each of these groups indicate the speed of the ballistic wind in miles per hour. (8) The sixth and seventh figures in each of these groups indi¬ cate the ballistic density in percentage of standard. (9) The following is an example of meteorological message 3 for artillery: Code groups Explanations MIFMIF_ The letter M indicates that the message is a meteorological message. The letters IF are the code designation of Fort Sill, Okla. The code letters MIFMIF indicate that the message contains meteoro¬ logical information from Fort Sill. 31256... The figure 3 indicates that the message contains data for terrestrial artillery; the figures 12 indicate that the meterorological datum plane (M. D. P.) is 1,200 feet above sea level; the figures 56 indi¬ cate that the temperature at M. D. P. is 56° F. BASIC FIELD MANUAL 279 The remaining groups of figures indicate the direction and speed of the ballistic wind and the ballistic density for maximum ordinates, as follows: Code groups Maxi¬ mum ordinate (feet) Ballistic wind direction Ballistic wind speed (m.p.h.) Ballistic density 0320896_ Surface. 32 8 96 1351196_ 600 35 11 96 2371496_ 1,500 37 14 96 3401596_ 3,000 40 15 96 4441696_ 4, 500 44 16 96 5481896_ 6,000 48 18 96 6502197_ 9, 000 . 50 21 97 7532297_ 12,000 53 22 97 8562497_ 15,000 56 24 97 CHAPTER 9 SIGNAL SUPPLY 252. Responsibility for supply.—The unit signal officer is responsible for the supply of Signal Corps equipment throughout the unit. The unit signal supply officer is charged with the actual procurement and distribution of these supplies. His general duties are prescribed in Army Regulations and in other orders and regulations pertaining to supply. In divisions the duties of unit signal supply officer are performed by the supply officer of the division signal company or the division signal troop. 253. Signal supply establishments.—Certain establish¬ ments for the storage and issue of Signal Corps supplies are organized in the theater of operations by divisions and higher units. The types and quantities of supplies stored in these es¬ tablishments depend on the nature of the operations and are varied to meet the probable needs of the troops at any time. The amount of Signal Corps equipment stored in the combat zone is kept to a minimum at all times. 254. Methods of supply; general.-— a. Signal supplies be¬ long either to Class III or Class IV. During active operations such items as field wire, batteries, and tape, the distribution of which depends upon the nature of the operations, become Class IV supplies. The issue of Class III and Class IV signal supplies is made in conformity with the provisions of Manual for Commanders of Large Units, Vol. II. 6. In emergencies the unit signal officer may call on the signal officer of the next superior unit for supplies needed for immediate use, to be furnished if practicable from the reserve stock of the superior unit. c. Requisitions are not forwarded to higher authority while the lower unit has supplies at its disposal from which requisitions may be filled. 255. Signal supply in the division.— a. Requisitions from unit signal supply officers are reviewed and consolidated by the division signal officer. The latter prepares a consolidated requisition which is forwarded to the army signal officer. 280 APPENDIX RADIO COMMUNICATION EQUIPMENT (This table is prepared for general information only. It should not be used as basis for requisitions) 1 2 SCR No. Set box No. 77-B_ BC-9-A_ 79-A_ /RC-32-A_ \BC-40_ 82_ 95_ BC-40_ 10S-A..... |BC-86-B_ (BC-98-B .. 109-A, modified.. . 127.. (sCR-125-A.. /BC-86-B_ (BC-98-B_ BC-7.. 130... BC-7_ 131. BC-148_ 132 (BC-127_ JBC-118-A-... 133.. (BC-138_ (BC-131_ BC-152_ (BC-129-. 134... BC-130_ BC-114_ (BC-162. 135 BC-119_ (BC-110_ BC-152_ BC-120_ BC-121_ /BC-122_ 159__ (BC-137_ /BC-86-B. (BC-98-B. BC-151_ 161.... 162. BC-150_ BC-153.. BC-129... BC-130.. 163.. BC-144_ BC-157_ 1fi7 / BC-123.. 168_ BC-126_ BC-10-C_ IfiQ j PE-43.. 171. BD-61_ BC-156_ Description Set, loop telegraph.... ? Set, transmitting and receiving telegraph. Set, battery charging 2 -KW, 25 and 115 v. Set, wavemeter_____ Set, telegraph and telephone transmitting and receiving. Uses antenna, type AN- 8 -A. jset, telegraph, modified for CW only_ /Set, transmitting and receiving telegraph, l pack. Set, transmitting and receiving telegraph. Set, loop telegraph... 5 6 7 8 9 10 11 Transmitting Receiving Described in RCP No. 43. RCP No. 17. TR 1215-5.... RCP No. 28. jRCP No. 27. ___do_ }RCP No. 26. _do. TR 1210-50— Type CW. ..do. (CW... ICW.. lTp-_- ,3et, transmitting and receiving, telegraph and telephone. Set, airplane telephone__ Set, airplane telegraph and telephone. Set, airplane telephone. TR 1210-30- Set, ground telegraph and telephone. /BC-152 receiver described in: \ Instructions GEI-4234. TR 1210-5.... CW. __do. ..do. —do. Range (miles) 3-5. 20 .. CW-60-. ICW-30. Tp. 20- Set, loop telegraph.. Wavemeter_ _do.. /BC-152 receiver described in: \ Instructions GEI-4234. TR 1210-20. ]RCP No. 27 TR 1210-40. (ICW_.._ iTp- |CW. (ICW— ITp. Set, telegraph. Set, airplane interphone, 5 stations .. jset, battery charging kilowatt, 32 volts. jTR 1210-75. TR 1210-32. TR 1210-5.. TR 1210-5 .. (CW_ ICW____ tTp- CW.. (ICW... (Tp- CW_ 100 . 60.. 60... 5.... Frequency in kilo¬ cycles 4,100-4,400.. 273-600. (..do_ CW-600_ (icw_.._ IC W-600-. bp- Tp. 200_ | do 5... ICW_ CW-90_ ICW-90_ Tp. 30_ CW-250_ ICW-250_ Tp. 80.. CW-100_ ICW-100.... Tp. 30_ CW-80_ ICW-50_ Tp. 30_ /CW... ITp.... CW. TR 1215-6.. TR 1210-31. TR 1215-10_ CW. 273-600... j-600-1,000_ 600-1,000... 273-545_ 273-545. 3,960-4,360... 150-350:... Tubes or lamps used 3 VT-l. /2 VT-2. U LM-4 o-lO. 40.- 15... 856-1,499_ •400-857_ j-250—350_ 333-867_ 600-1,000... 3,760-4,120.. 100 - 2,000 _ 75-1,500. __ 12 VT-4-B. VT-2_ ,{? /2 VT-4 U VT-2 4 VT-2. 12 VT-4-B_ -2 _ Type CW. ...do_ /VT-2 or UX- 1 210 . /4 V \3 V T-4-B_ VT-22_ 3 VT-2.*. /! V 13 V T-2_ T-4-B. (CW... (ICW.. It p — CW_ ICW... Tp- CW.... ICW... Tp..... CW.... ICW... Tp. •CW. (CW_ ICW... [TP- 5 VT-4-B. 1 VT-2_ 3 VT-4-B... r-4-B. - 2 — /2 VTH \1 VT-5 3 UX-864_ (CW.... (iCW... bp_ (CW.. (ICW — [Tp—- CW.. ICW__ Tp. (CW.. ICW.. ITP—- (CW... |Tp- [iC W___ CW.... Frequency in kilo¬ cycles Tubes or lamps used 12 Power 4,100-4,400. 273-600_ 273-600_ [■273-1,000_ 273-1,000_ 3 VT-1. _do.. 1 lamp LM-4. 3 VT-l... 4-v. storage battery..... Dyn. PE -6 350-v. fin. 12-v. stge. (100 w. input).. Gas. Eng. GE-2 Gen. GN-9. Buzzer and battery_ J-27: 850-1,500... 3,820-4,190... 2,640-3,040. 3 VT-2_ 2 UX-210_ 3-857_ 273-857. 3,960-4,360... 100 - 1,000 _ 250-1,500_ 250-1,500_ 250-1,500_ 333-857. 273-1,000_ .do_ 3 VT-7_ _do_ 3 UX-864. 7 VT-5_ /Dyn, DM-13-B or C, 750-v. from 12-v. storage [ battery or motor generator type MA-4. /Dynamotor and storage battery or motor gener- 1 ator. Hand-driven 350-v. and 8 -v. generator, GN-29-A. Dyn. PE-5 to 350-v. fm. 12-v. storage battery_ Hand generator....... 8 VT-5. -do.. _do.. 4 VT-5. 3 VT-l. |CW..._ (ICW... [Tp- CW_ CW... 3,760-4,120...| 3 UX-864. 100 - 2 , 000 ... 75-1,500_ 600-1,300_ 3,820-4,180... 2,640-3,040... 4 VT-5. _do.. Motor generator GN-32 or MG- 8 . 2,000-v., 110-v., and 12-v. DC from 110-v. or 220-v. AC power lines or power equipment type PE-40. • Dyn. BD-46. Driven from central power plant. Dyn. BD-41 driven from central power plant... Dyn. Unit BD-43.... (PE-41 Gas engine driven generator 10 and 800-v. \ or motor generator type MA- 4 . (Dyn. DM-13 B or C 750-v. fm. 12-v. storage bat- l tery. (25 watts output.) Hand generator. Buzzer__ ....do__ Dyn. Unit BD-46. Hand generator... Gas engine and dynamotor. Hand generator_ 13 14 15 16 17 Spare vacuum tubes or lamps Storage batteries Dry batteries In use Spare In use Spare 3 VT-l_ 1 BB-41... 2 BB-41— 9 BA-2.... 6 BA-2.... (3 VT-l_ 1 /1 BA-4.... \2 BA-2_ 3 BA-4.... 2 BA-2.... (2 VT-2_ [3 LM-4_ )5 BB-29... 6 BB-29... 5 LM-4_ I BA-4— (2 VT-4-B_ (l VT-2.. Je BB-29... 6 BB-29.. 4 BA-2.... 4 BA-2 [3 VT-l_ (2 VT-4-B_ (1 VT-2_ [..do. __.do_ ...do_ _.do [3 VT-l_ /5 VT-2_ 16 VT-7.. 1 )_ /2 BA-8.... |3 BA-23. 2 BA-8.... 9 BA-23— 2 BA-8.... J [5 VT-2_ J 3 BB-29... 6 BB-29... 2 BA-8.... (4 VT-l.... 6 UX-864. . . 12 BA-23... \2 BA-2_ 4 BA-23... 4 BA-2_ (14 VT-5... (8 VT-4-B [6 VT-22... jl BB-41... 1 BB-41... |4 BA-23... (2 BA-8.... U BA-1_ 8 BA-23... 2 BA-8.... 1 BA-1.... /8 VT-5... jl BB-4_ 2 BB-4.... 3 BA-2.... 6 BA-2.... \3 VT-2... (1 VT-2.... 1 (3 VT-4-B l8 VT-5... j-.-do.. ...do_ ...do.. .-.do_ (1 VT-2... ] (5 VT-4-B. >..do_ do ... _ do_ do [8 VT-5.... | |1 VT- 2 .... ) (3 VT-4-B. . [8 VT-5... >1 BB-41.. 1 BB-41... 2 BA- 8 .... 2 BA- 8 .... (2 VT-4-B . (l VT- 2 .. je BB-29... 6 BB-29 4 BA- 2 .... 4 BA-2.... [3 VT-l.... 6 UX-864.. /2 BA-23... 4 BA-23... - .. \2 BA-2_ 1 BA-27... 4 BA-2.... 1 BA-27.. _uo_ /3 VT-2_ jl BB-4.... 1 BB-4.... 2 BA- 8 .... \4 VT-5. 2 BA- 8 ... 8 VT-5.. /4 BA-23... 8 BA-23... (2 BA -8 _ 4 BA -8 _ . ---- — . .-. . 18 Remarks Same tubes used for transmitting and receiving. Nine tuner settings. ( Weight: 850 pounds. jVT-7 same as Westinghouse WX-12. Junder development. I Ground to air range is approximately one-half of j that shown. Obsolescent. Do. Same as SCR-109-A except for antenna. (Same tubes used for transmitting anti receiving / Under development. junder development. (For intercommunication within observation or , attack airplane. May be connected to radio ( receiver. For intercommunication within bombardment ^dr£lane ; _J\fay_be connected to ra dio receiver. Weight: 225 pounds. Under development. Switchboard, one master position and 20 student positions for teaching code. Legend: SCR-Set designation; C W = Continuous wave telegraph; D. B. = Distribution box; BC = Set box designation; ICW = Modulated CW; RCP = Radio Communication Pamphlet; VT = Vacuum tube; Tp = Telephone; TR = Technical Regulations- LM = Lamp- Dyn =D namotor 1143°—31. (Face p. 281.) ’ ’ Uam ° ° r ‘ riPME: be used 1 2 SCR No. Set box No. 77-B . _ BC-9-A_ 79-A /BC-32-A_ 82 _ \BC-40__ 95 BC-40_ 108-A . _ IBC-86-B_ < B C-98-B_ 109-A, modified... 127__ [SCR-125-A... /BC-86-B_ \BC-98-B_ BC-7_ 130. .. _ BC-7_ 131... BC-148.. 132... fBC-127... BC-118-A_ 1BC-138_ BC-131_ BC-152_ BC-129_ 133_ 134___ BC-130_ BC-114_ BC-162_ 13K BC-119_ (BC-110_ BC-152_ BC-120_ BC-121_ fBC-122_ 159_ [BC-137_ (BC-86-B_ De^ or s Set, loop telegraph. Set, battery charginjvv — Set, wavemeter_f" 1-4 - Set, telegraph and te. receiving. Uses a; Set, telegraph, modi 1 - (. pack. Set, transmitting an-- Set, loop telegraph.. 4 - Set, transmitting am telephone. ■Set, airplane telepho- Set, airplane telegra]}- Set, airplane telepho- Set, ground telegrapl- 4 I P\ l { l B B Pj r i i ri wa BASIC FIELD MANUAL 281 b. During active operations the division normally obtains its signal supplies directly from the army signal depot. When speed of supply is not of great importance, supplies may be ob¬ tained directly from the communications zone. c. Upon arrival of the supplies at the refilling point they are distributed under direction of the division signal officer. He uses for this purpose the personnel and transportation of the supply section of the division signal company as far as practic¬ able. The division quartermaster train may assist in emer¬ gencies. Signal supplies may be delivered directly to lower units from the refilling point, but it is often necessary to establish a distributing point, where distribution is made to the trains of the lower units. The distributing point may coincide with the division signal dump. d. The division signal officer is responsible for charging the storage batteries of all units not equipped with charging plants. The division charging plant is operated by the division signal company. It is normally located at the division signal dump. Three sets of storage batteries are a component of most field radio sets. Prior to combat every effort is made to provide each radio set requiring them with two fully charged sets of batteries. In active operations one set of batteries will normally be on charge, one in transportation between the radio station and the charging plant, and one in operation. During combat the col¬ lection and distribution of storage batteries pertaining to radio stations of the lower units is usually made by the division signal company at distributing points, jauwam cmh i% oisact ■ .tnqob lsirt^h /an & ■ ■ . . ’ M'jft Jaom tb friohoqmboi & mn ashofrad V &j.oh otnifT rff,w ebivoi^ot al.>atif M J-iofl* ^T9Vf> Mckiyoft- 1 -i ion! . -. , „i -Io‘) Of li indcaoo s ihaQ aoiiAVX(o ci a/;- ! ,, ,An*I aafcm;. ;•> U lyw aoiai/ib aiii vd t>i>w \iUihti- i idd; - ( ,v,f , ; i j . , ,ai£jk*j gniJudhtaib U ^xutqmoa . - * INDEX Para¬ graph Page Abbreviations... 198 204 Agencies, communication_ 7 5 Aircraft, releasing pigeons from__ 239 254 Airplane messages, dropped and pick-up_ 184-193 197-201 Army and Navy methods of specifying time..__ 229 247 Artillery fire, control by radio_____ 139 155 Assignment of frequencies_ 90 112 Authorized military ciphers_ 905 209 Authorized military codes____ 204 208 Batteries: Dry..--- 80 100 Dry, general construction___ 142 178 Storage, care and charging__1_ 144-158 180-183 Buzzer, service__ 68 82 Buzzer phone___ 67 81 , Description and testing_ 83 106 ; • > Cable for monocord switchboards, preparing_ 50 57 Call signs, radio, and telegraph_ 232 248 Calls, radio__ 104 118 Care: Of dry cells- 143 179 Of pigeons at message center___ 235 248 Centrals: Switching-..._ 16 n Switching, installation of_...__ 56 71 Telephone, installation of_ 55 68 Cipher device, type M-94_ 207-214 211-220 Ciphers, authorized military___ 205 209 Circuit: Diagram_ 19 14 Ground return__ lid 7 Marking tags_:_ 27 31 Phantom.....1-'.--- 52d 63 Simplex...'.-........--- 52c 63 Terminals, construction at__ 37 45 Circuits: Local---_;... lie 7 , • Metallic_ lid 7 Patching---...-......._..._ 76 97 Periodic tests of_ 72 84 Phantom.__ lie 7 Simplex--...__ lie, 69 7,83 Trunk..... 11c 7 1143° 31-10 283 284 INDEX Para¬ graph Page Climbing, pole.*---- 30 36 Code names, telephone- 231 247 Use of_ 46 54 Codes and ciphers---'- 96,203 115,207 Rules for use of- 206 209 Codes, authorized military-*- 204 208 Codes, meteorological message---—-■- 251 272 Coils, repeating: Description and testing- 85 109 Use and installation- 52 62 Collective wire systems_ H 6 Command post, wire communication during movement of- 14 8 Joint-axis method_ 14c 10 Multiple-axis method- 146 » Single-axis method- 14 fl 9 Communication: Agencies_ 7 Officer, duties_—- 1 J Orders and instructions- I 7 i2 Units, cooperation between- 9 5 Composition of wire systems- H 6 Construction: At circuit terminals- 37 45 Orders_ 40 49 Overhead_ 33 40 Surface line_ 32 • iS Test station_ 38 46 Trench line_ 42 51 Conversations, telephone- 45 53 Converting a test station into a telephone central-— 57 71 Cooperation between communication units- 9 5 Cooperation, radio stations, with message center- 101 117 Crossings: Railroad_ 35 42 River_ 36 42 Road_ ------- 34 40 Cryptograms, use of_ 200 204 Cryptography, military- 200-206 204-209 Defective circuits, testing- 74 93 Definition of message- 195 202 Definitions of wire lines_ 31 38 Designating lines and circuits- 21 16 Designations, telephone, for officers and offices- 47 54 Diagram: Circuit-- 19 14 Traffic_ 55 80 Division of duties_ 6 ■'* Division wire system_ H 3 Dropped and pick-up airplane messages- 184-193 197-201 INDEX • Dry batteries__ _____ Para¬ graph 285 Page General construction _ IUU 1 7C Dry cells, care of_ I/O 170 Duties: i/y Division of_ A Of communication officer-.. 2 Of unit signal officer.... 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