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|275k||Lookouts in Aft Conning Tower aboard the Indiana (BB-58). |
The development of efficient communcations is one of the most important problems in the training of the fire control organization with its various activities and its widespread stations. Successful communication requires first of all, a satisfactory system of telephones and other transmitting instruments, and second, properly trained personnel.
The first requirement is met by our Sound Powered Battle Telephone System.
The second requirement however, is not one that can be met by mechanical perfection of instruments, or by prescribing hard and fast rules for personnel.
It demands careful indOctober rination and training so that every individual is familiar with the problem at least as it concerns his immediate station and those with which he is in communication, and is prepared to act intelligently in any contingency.
Many communication difficulties arise from the fact that parties in communication cannot see each other.
For example, failure to receive acknowledgement from a station to which a message is addressed may mean that the station is out of commission, that its talker is momentarily so occupied that he cannot reply, or that he is asleep.
It may be impossible to determine at once which of those conditions exist.
Judgement must be exercised in such situations so that communications may be re-established quickly and with the minimum of interference to other activities.
Efficient fire control communication, upon which success in action depends, is obtained by standardized procedure, intelligent talkers and such intensive training that the personnel become completely familiar with any type of situation which may be encountered.
Fire control telephone circuits are party lines providing communication between several stations. For instances on the Captain's Battle Circuit there may be as many as ten parties at the same time. When any talker pushes down his button and speaks, all others on the circuit receive his message. With many communications to be transmitted, each must be of the utmost brevity consistent with clarity.
In action, or at any other time, communication conversation in the usual sense has no place on a fire control telephone circuit.
The demand for brevity has resulted in the development of numerous stereotyped phrases and modes of expression.
They constitute what may be termed the "fire control language".
Familiarity with it can be acquired only through training, but certain elements must be learned as a preliminary phase of such training.
All numerals indicating measurements of distance, spot, range, director angle, deflection bearing, etc., are transmitted over the telephone circuit by speaking each digit separately, with the exception that when the last two digits are zeros they are transmitted "double 0". Zero is generally expressed as "Oh" instead of "zero".
MESSAGE TELEPHONE TRANSMISSION- Range 13350 "Range one-three-three-five-O". Range 12500 "Range one-two-five-double-O". Range 12000 "Range one-two-O-double-O". Deflection 540 "Deflection five-four-O". Spot up 100 yards "Up one-double-O". Spot up 20 mils (AA) "Up twenty". Bearing 054 degrees "Bearing zero-five-four".
NOTE- The numeral 0 is spoken "zero" when used with bearings.
An important feature of the fire control language is the manner of calling a station, and of replying, or acknowledging.
Ordinary practice in a telephone conversation is to call a person by name, and to await acknowledgement before proceeding with the - message.
This procedure is logical when the party calling has no assurance that the party called is listening. On a fire control circuit such a condition does not exist.
The first step in manning battle stations is to establish communications ; once established they must be maintained as long as communication lines remain intact.
If one station has information to transmit to another, it is unnecessary first to call the station and receive an acknowledgement before giving the message.
It is presumed that all stations are on the circuit and listening continuously.
Where several stations are on the same circuit and it is desired to address a message to one of them, the correct procedure is to give the call of that station and follow it immediately with the message.
The station addressed then acknowledges by repeating his own call followed by "aye, aye".
For example Air Defense wishes director 3 to train to 125 degrees relative.
He says : "SKY THREE TRAIN ONE TWO FIVE" and Sky 3 answers "SKY THREE AYE, AYE".
If the station transmitting the message does not receive an acknowledgement immediately, it repeats the call and message.
If after several repetitions no acknowledgement is received, the calling station should establish communication by some other means and determine the casualty.
If a message is heard by the station addressed, but not understood, that station should say at once "Repeat", and the transmitting station should then repeat both the call and the message.
When a message is addressed to several stations simultaneously the procedure is the same as for a single station except that a collective call (or the individual calls of the several stations) precedes the message.
Acknowledgements are made in numerical sequence, as briefly as possible.
In such cases the "aye, aye" may even be omitted.
Stations slow to answer are skipped and come in at the end.
If a station fails to answer in its proper turn, the next following should, after a short pause, take up the sequence.
The station that was late may then answer at the end.
During standby intervals, and sometimes during active periods, it may be desirable to comunicate with a station for the purpose of testing the circuit. If a station is addressed solely for test, the procedure is to speak the call as usual, followed immediately by the call of the calling station and the word "testing".
The acknowledgement is made in the usual way.
In all the fire control stations there are numerous outlets from the various battle telephone circuits.
There is usually a principal circuit over which the officer in charge of the station listens, but in most cases it must be necessary for him to be able to shift to any of a number of circuits.
In order that all necessary circuits may be guarded continuously, he has a talker on each circuit.
The selective switch controlling the connection of his telephone permits the officer in charge to shift to various circuits as the situation may demand, but even when these selective switches are provided, it is necessary for the officer in charge of a station to communicate over several circuits through talkers.
These men hold very important positions, yet they cannot be expected to possess the experience and judgement of the officer in charge of the station.
In order that there may be no possibility of having the substance of a message altered due to misunderstanding or misinterpretation by a talker, the responsibility for framing a message rests with the officer originating, it.
Once delivered to a talker, it must be transmitted in exactly the same words; and the talker receiving the message at the other end must repeat it to the officer concerned in the exact form in which it is heard.
In brief we have two principles governing the control communication by talker:
(a) The person originating the message must state it in the exact words in which it is to be transmitted.
(b) The talker transmitting a message must repeat the exact words of the originator, and the talker hearing the message must repeat word for word what he heard.
Acknowledgements belong in the same category as messages.
An acknowledgement signifies that the message has been heard and understood.
It is the responsibility of the person addressed to understand the message, and it is he who must originate the acknowledgement.
An exception to this rule applies in the case of the transmission of data in which the acknowledgement consists of a repetition of the message.
For example, Sky 1 transmits the target angle to plot.
The correct message is "TARGET ANGLE TWO SEVEN ZERO", and the correct acknowledgement is an exact repetition of the message.
Another exception applies where a message is not heard distinctly or not understood.
If a talker does not hear a message distinctly, he must call for "repeat".
If the person addressed does not understand the message, he in turn must call for repeat.
It is to be noted that the responsibility for understanding a message does not rest with the talker, and as long-as the talker hears a message distinctly, he must repeat it exactly as heard, whether or not he understands its significance.
It is the duty of the person addressed to determine whether or not the message is intelligible. Much confusion and loss of time results from talkers asking for a repeat on messages which they do not understand but which the officers addressed probably would understand.
Of course it is highly desirable for talkers to be trained to understand all messages that they are likely to transmit and receive.
The handling of messages thereby becomes much more accurate and rapid.
SOUND POWERED TELEPHONE
The RCA sound powered telephone consists of a transmitter and one or more receiver units.
The system generates its own transmitting power and should never be operated in conjunction with power operated telephone systems.
The "motors" used in the transmitters and receivers are essentially the same, but differ in a few points such as size, shape of armature, number of turns and size of wire in the operating coils.
In the sound powered telephone system, all motor units, both transmitting and receiving, are connected in parallel.
An open circuit line switch is inserted in series with each transmitter (the button on the mouthpiece) thus eliminating unnecessary noises on the line from transmitters not in use.
The switch must be depressed while talking into the mouthpiece.
Sound powered telephones are moisture proofed and will withstand immersion in water without damage to the mechanism.
The telephones are designed to operate efficiently under most conditions encountered in marine practice, even under pressures varying widely from atmospheric pressure.
Figures A, B, and C illustrate, in a simplified manner, the functioning of a sound powered telephone motor unit.
Note that the unit consists of a coil located within the field of a permanent magnet.
An armature passing through the coil, shown in A, is centered within the air gap between the two poles.
The armature is connected, by means of a drive rod, to the diaphram.
Note that the magnetic lines of force, represented by the arrows, pass from the North to the South pole of the magnet.
With the armature in this position no magnetic lines of force are passing vertically through the coil.
When the motor unit is used as a transmitter, the sound waves compress the air before the diaphram, forcing the diaphram in, thus moving the armature to the right, as illustrated in B.
In this position the armature nearly bridges the air gap and forms a much better path for the magnetic lines of force than the air did.
Magnetic lines of force are therefore, conducted along the armature and up through the coil in a vertical direction, inducing an electric current in the coil.
Since sound waves are vibrations, causing compression and refraction of the atmosphere in which they travel, the diaphram will vibrate with the waves and remain in any one position only an instant.
After reaching the position shown in B the diaphram moves outward to the position shown in C, forming a path for the opposite direction.
Thus it can be seen that when the diaphragm is actuated by sound waves, the motor unit generates corresponding electric impulses which are fed to a second motor unit employed as a receiver.
When a motor unit is used as a receiver, the action taking place is the reverse of that when used as a transmitter.
When used as a receiver, elecrical impulses entering the coil magnetize the armature.
Magnetic poles of the same polarity repel each other, and those of opposite polarity attract each other.
The current flowing through the coil in B magnetizes the armature in such a direction that the top of the armature is "N"; therefore it would be repelled by a North pole and attracted by the South pole of the permanent magnet, thus drawing the diaphram inward.
As the direction of the current reverses, the polarity of the armature reverses, and its position in the air gap will be reversed, forcing the diaphram outward, thus compressing the atmosphere before it.
It can be seen that the diaphram of the receiver will vibrate in unison with that of the transmitter and excite corresponding sound waves in the atmosphere before it.
The headset type sound powered telephone consists of a transmitter mounted on a chest plate equipped with a junction box, a pair of earphones and connecting cable and plug.
The transmitter is equipped with a line switch connected in series with the transmitter coil.
When he switch is depressed the earphones and transmitter units are connected in parallel.
To use the sound powered telephone headset, proceed in the following manner:
(1) Remove phones from box, being careful not to handle by means of the cords.
Straighten out cord, eliminating all twists and kinks.
(2) Place plug in proper receptacle, see that it is firmly seated and that the clamping ring is firmly tightened on the threaded collar.
(3) Adjust the headset so that the earpieces rest comfortably but firmly against the ears, and the chest plate so that the mouthpiece is directly in front of the mouth, and as close to it as convenience and the construction of the unit will permit.
(4) Press the switch on the transmitter to establish contact with the line and test as outlined under procedure (Art. 1-3).
(5) Speak distinctly-shouting does not help.
(6) Release the transmitter switch while listening, but do not under any circumstances, held the switch down when the transmitter is not in use because all the noise of action etc.,will be transmitted over he circuit.
(7) When securing the phones, place them in the designated stowage.
This may mean either that they are to be disconnected from the line, made up and stowed in a box, or that they are to be left on the line, hanging the chest plate and headset up on the hook provided.
Do not hang the connecting cord, use the straps provided.
NOTE- It is important that all persons wearing sound powered telephone headsets remember that the earpieces are transmitters and will pick up all noises in the vicinity.
This could cause the utmost confusion in battle.
When you are wearing sound powered telephones keep them tightly over the ears.
Sound powered telephones are ruggedly constructed, and with reasonable care, should require little attention.
Only authorized persons (E Division personnel) shall remove the units from their housings, or in any way tamper with them.
Do not insert any foreign object through the protective screen of any telephone unit, as the diaphram may thereby be damaged.
Damaged phones, or phones out of order, shall immediately be reported to the IC Room.
Procedure for Handling Battle Telephone Casualties.
The control (or senior station) on each battle telephone circuit, in the absence of traffic on that circuit during general quarters, will test communication with all stations at intervals of about five minutes, and always immediately after it is obvious that the ship has received a hit or other severe shock.
In Condition II and III this test should be conducted about every fifteen minutes.
Whenever a station cannot contact another station on a circuit, the talker will immediately inform the officer in charge at his station.
Each talker will test his own telephone every minute by lightly blowing in the mouth piece.
Any battle telephone talker who does not hear traffic (conversation) or the above test (about every five minutes), will test communication from his station, then if no answer is obtained from any station the talker will check the Jack plug for secure contact, and then blow into his mouthpiece.
If his headset is functioning properly he will hear this (blowing) in his earpieces.
If the headset is defective, lie will hear nothing.
A short circuit in a single headset will render the entire circuit inoperative.
Remove the headset and man one of the spare headsets at that station and repeat the above tests. If communication still cannot be established, he will:
Unjack from the primary outlet and plug in the auxiliary outlet for that circuit if one is provided. Test communication over the auxiliary circuit.
If no response, then:
Use the nearest ship service telephone and call a station on the defective battle telephone circuit (preferably the control or senior) station and report your station's "Primary ………circuit out;
have shifted to X.......”
That station if possible will relay this information to all other stations on the defective circuit, and:
All stations on the defective circuit will shift to the auxiliary circuit where provided.
NOTE-In case of casualty to the primary JA or 1JV circuits in Conn, the word will be passed immediately over the 1MC announcing system "All stations shift to XJA or X1JV".
Similar procedure will be employed with discretion for other announcing systems in case of any battle telephone casualty.
If both primary and auxiliary circuits fail to provide battle telephone communication, certain stations may still maintain restricted communication by:
(a) Ship's service telephone.
(b) Announcing system such as 2MC, etc.
(d) Long emergency telephone leads.
To facilitate the above at general quarters one ship's service telephone in Batt Two (056), Conn (233) and Fire Control Tower (602) will be made "Executive Right-of-way Phones".
|Photos & text courtesy of Pieter Bakels.|
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