794 



Popular Science Monthly 



When stations calling each other are 

 close by, or within easy communication 

 distance, it is not necessary to repeat the 

 call letters three times either in calling or 

 acknowledging. For instance, a so-called 

 "short call" might be as follows: 



"Dash-dot-dash-dot-dash KURde KSW" 

 and the acknowledgment or reply simply 



dot). This "End of message" signal is 

 written as a cross (+), and, as indicated 

 before, is often used at the end of any 

 transmission whether of a complete mes- 

 sage or not. The double-dash ( = ) signal, 

 dash-dot-dot-dot-dash, is used to separate 

 the preamble from the address, the address 

 from the text and the text from the 



i imi ta mi mm imiiiiiii i i m — i i w 



3 AM 



mi i i vmm tJTT-ngp-r 



J 



n: 



FI6. 14 



How the "break" or double-dash is used to separate the preamble from the address. Note the 

 extra space between the figures for the hour and those for the minutes in the space for time filing 



the letter "K," meaning "go ahead." Such 

 shortening of the time used for calling and 

 establishment of communication is very 

 helpful in working radio where much traffic 

 is to be handled, since every minute saved 

 for actual messages increases the number 

 of useful words which can be put through 

 in a given time. The formal symbols 

 should never be abbreviated to the point 

 where uncertainty creeps in, however, for 

 in such cases more time is lost in repeating 

 than would have been taken for a complete 

 transmission in the first place. 



The Authorized Message Form 



Assuming that the call and reply have 

 been given, the acknowledging station indi- 

 cating by "K" that it is ready to receive, 

 the calling station may begin its transmis- 

 sion of messages. According to the Naval 

 system (which is similar to that in use else- 



signature and should never be omitted. 

 The preamble referred to needs further 

 explanation. It contains the necessary 

 information for the operators' records, 

 and usually consists of seven parts, as 

 follows: (i) prefix, (2) station of origin of 

 the message, (3) number of the message, 

 (4) the signature-letters of the sending or 

 receiving operator, (5) the "check," or 

 number of words in the message, (6) the 

 date and hour the message was filed for 

 transmission, and (7) the route or "Via," 

 giving the call-letters or the stations which 

 have relayed the message up to that point. 

 The prefix is a code-letter symbol, such as 

 "TR" for a position report giving the loca- 

 tion of a ship at sea, "OFM"'for an official 

 message, "SVC" for a so-called "service 

 message" (which is one sent between sta- 

 tions and having to do with handling mes- 

 sages, accounts, traffic regulations, etc.), 



I I I □ I I H PTT 



HUHHI ■IIHB B 1II 

 G H T 



□ I I I I I I I I 1 I I I I I 1 I II I I I I I I I I I I I I I I I I I I I I I 1 I I I I I I I I I I I I I I I I I I i I I I i: 



FIG. 15 



The close of the specimen message, showing the double dash separating the text from the signa- 

 ture, and the cross, or " end of the message " character, spelled out in the usual way 



where) the message transmission may be 

 divided into six main parts, as follows: 

 (1) Attention signal, (2) Preamble, (3) 

 Address and route, (4) Text, (5) Signature, 

 and (6) End of message (dot-dash-dot-dash- 



"MSG" for a private or unofficial message, 

 or "RADIO" for a commercial message. 



The name of the station (2) is spelled out, 

 as is the day of the month under (8) — the 

 name of the month is omitted. The num- 



