INTRODUCTION TO SONAR 



Proword 



Meaning 



THIS IS This message is from . 



TIME What follows is the time or 



date-time group of this 

 message. 



TO This message is for action 



by and is directed to 



WAIT I must pause for a few 



seconds. 



WAIT OUT I must pause for longer than 



a few seconds. 



WILCO I have received and under- 

 stood your message, and 

 you have the assurance 

 of the command that it 

 will be complied with. 

 (This type of answer re- 

 quires CO's permis- 

 sioa) 



WORD AFTER .... The word after (word) 



(word) is . 



WORD BEFORE . 



(word) 



WRONG 



The word before (word) 

 is . 



Your last transmission 

 was incorrect. The cor- 

 rect version follows. 



INTERNATIONAL MORSE CODE 



The International Morse code is a telegraphic 

 alphabet, which is another way of saying that it 

 Is a dot and dash communication system. The 

 code is pronounced by saying "dit" and "dah," 

 not "dot" and "dash," so forget about dots and 

 dashes and think only in terms of dits and dahs. 

 The group of dits and dahs representing each 

 character must be made as one unit, with a 

 clear break between each dit and dah, and a 

 much more distinct break between characters. 



Never try to identify a character by counting 

 dits and dahs. Don't let yourself get into this 

 habit. It's a temptation at first, but you won't 

 be able to count fast enough when the code speed 

 picks up. Learn sound patterns instead. To 

 tmderstand what this requirement means, rap 

 out the pattern beginning "Shave and a haircut." 

 You recognize this ditty from its characteristic 

 rhythm, not because it has a certain number of 

 beats in it. You must learn code the same way. 

 Each character has its own distinctive sound 

 pattern. With study and drill you wUl learn to 

 recognize each pattern as fast as you now 

 recognize "Shave and a haircut." The accent 

 always falls on dahs, and you should pronounce 

 each rhythmical combination with that rule in 



mind. Go through the alphabet several times 

 to get the feel of the sound of the dit-dah com- 

 binations. 



The Code 



In the pronunciation guide for the soimds of 

 the characters in the accompanying list, the 

 sounds are written out phonetically insofar as 

 possible. The short sound "dit" actually takes 

 on the sound "di." The "i" is very short and 

 the "t" is dropped. 



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