Chapter 8 — COMMUNICATIONS 



"Repeat all of your last transmission." Fol- 

 lowed by identification data, it means "Repeat 

 the indicated portion of your transmission." 

 The answer to SAY AGAIN is I SAY AGAIN, 

 followed by the repetition requested. Example: 

 WEASEL asks LONGSHOT to repeat all of his 

 last transmission, and LONGSHOT complies. 



Tins IS WEASEL — SAY AGAIN — OVER 

 THIS IS LONGSHOT — I SAY AGAIN — 

 WEASEL— THIS IS LONGSHOT — BREAK- 

 CHANGE BASE COURSE TO ZERO NINER 

 ZERO— MAINTAIN PRESENT DEPTH AND 

 SPEED— REPORT WHEN READY— BREAK 



If WEASEL missed only the word PRESENT, 

 he would frame his request as follows: 



THISIS WEASEL— SAY AGAIN— WORD AFTER 

 MAINTAIN — OVER 



When WEASEL has the complete m?ssage, he 

 sends a receipt. 



Canceling a Message 



To cancel a message in progress, cease 

 sending immediately and transmit the proword 

 DISREGARD THIS TRANSMISSION. Example: 

 LONGSHOT'S operator begins a massage, then 

 is ordered to delay it. 



WEASEL — THIS IS LONGSHOT — TAKE STA- 

 TION — DISREGARD THIS TRANSMISSION 

 — OUT 



Underwater telegraph procedure closely 

 parallels underwater telephone procedure. Con- 

 struction of messages is the same, and so are 

 principles of calling, receipting, correcting 

 errors, waiting, and obtaining repetitions. You 

 will notice two important differences, though: 

 Instead of using voice calls, you will use the 

 international call signs of the ships. Also, in- 

 stead of prowords, you will use prosigns. 



Call Signs 



Call signs are letters or letter-number com- 

 binations. They are used chiefly for identifica- 

 tion of a communication activity. By international 

 agreement, the United States has the use of the 

 first half of the A block (assigned to Army and 

 Air Force units) and all of the K, N, and W 

 blocks. You are already fam.'liar with the K and 

 W calls. They are assigned to commercial radio 

 stations. Your concern here is with the N calls, 

 assigned to the Navy, Marine Corps, and Coast 

 Guard. Naturally, your primary interest is with 

 U. S. Navy ship calls. 



The Navy assigns a 4-letter call to each of 

 its ships. Should the need arise, you can find 

 the international call of any Navy ship in ACP 

 113, Call Sign Book For Ships. Following are 

 a few examples . 



Shi2_ 



Call Sign 



USS Cony (DD 508) NILX 



USS O'Bannon (DD 450) NUJC 



USS DuPont (DD 941) NTIR 



USS Seawolf (SSN 575) NBWY 



Call 



Once a message is receipted for, it cannot be 

 canceled by means of the proword DISREGARD 

 THIS TRANSMISSION. Instead, a new message 

 must be sent. 



UNDERWATER TELEGRAPH PROCEDURES 



Knowledge of the Morse code itself will not 

 enable you to send a correct message. You also 

 miist have a working knowledge of simple radio- 

 telegraph procedure. You won't need to master 

 all the details because sonar communications are 

 kept to a bare minimum, and messages sent are 

 in brief, plain style. If you learn the procedure 

 given here, you will be able to handle any under- 

 water message you are likely to encounter. 



The call is a transmission directed to the 

 station with which you wish to communicate, 

 requesting that station to answer. Begin the 

 transmission with the call sign of the station 

 you are calling. Next, give the prosign DE(from), 

 then the call sign of your own sliip, and finally 

 the prosign K. In the following example the 

 USS Cony, a DD (call sign NILX), calls the 

 submarine Catfish (call sign NJRV): Call: NJRV 

 DE NILX K; reply: NILX DE NJRV K. Cony now 

 repeats the call without the prosign K and pro- 

 ceeds with the text of the message. 



After commimication is established, further 

 calling or answering incident to transmission of 

 a message usually is handled by abbreviated 

 calls. The abbreviated call omits the call sign 

 of the station called. If there is a possibility 



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