AEROGRAPHER'S MATE 3 & 2 



Most weather offices contributing to theCOMEDS 

 system should have a transmit facility and re- 

 ceive capability in each area. This system does 

 away with tape preparation entirely. Messages 

 are formatted and prepared on the keyboard dis- 

 play unit. Using this method, errors in trans- 

 mitted messages should decrease almost to 

 zero. As the message is typed on the key- 

 board, it is electrically stored and simultaneously 

 displayed on the display unit. This editing feature 

 permits you to correct such errors by changing 

 discrete characters or by adding or deleting 

 characters as needed without starting the message 

 over. All line signaling is done using the eight- 

 bit American Standard Code for Information In- 

 terchange (ASCII). This code makes use of a 

 parity check to ensure the validity of each 

 alpha-numeric character. 



The NOTAM-only circuit was eliminated with 

 the conversion to the COM EDS system; the re- 

 sponsibility of suppling NOTAMS to base op- 

 erations now rests with the weather office. 

 The observer terminal should be used for recipt 

 and transmission of NOTAMS. 



Automatic Response Query (ARQ) requests will 

 be made and responses received directly at the 

 work area where needed. Responses will be 

 directed to either the display unit (KD) or the 

 printer according to the directions. This pro- 

 cedure sharply reduces the amount of paper 

 being used. 



Automatic Polling 



Automatic polling of units on the COM EDS 

 circuit is accomplished by the computer sending 

 an invitation-to-send sequence which causes the 

 KD to respond in one of two ways: (1) If ready 

 to transmit, the KD sends its message begin- 

 ning at the location of the cursor, or (2) if 

 not ready to transmit, the KD sends a no- 

 traffic response. This polling is repeated for 

 each KD on the loop, thus completing the cycle. 



Dissemination Concept 



Messages may be sent by the computer at 

 any time. The messages are selectively addressed 

 and copied only by the receiving devices for 

 which they are designated. The concept for the 

 printer and the KD follows: 



(1) Printers - The computer sends a receive 

 device conditioning signal. The address code of 



each printer designated to receive the mes- 

 sage will then be sent, followed by the message. 



(2) Keyboard Display (KD) - The computer 

 sends a receive device conditioning signal and 

 one KD address code. This will cause the KD 

 to respond in one of two manners: (a) If the 

 KD is in a receive mode, the ready-to-receive 

 response will be sent to the computer which 

 then sends the message to the KD. (b) If the 

 KD is not ready to receive, a not-ready-to- 

 receive response is sent to the computer. The 

 message is sent to the computer, then to the 

 receive-only printer with which the KD is as- 

 sociated. 



NOTE: Complete details on procedures and 

 formats were not available at the time of this 

 writing. For a more complete and comprehen- 

 sive understanding of the system, refer to the 

 latest manual and instructions as they become 

 available. 



NAVAL COMMUNICATIONS 



Quite often, naval weather units must depend 

 on the naval communications system for the 

 dissemination of weather data. Of the several 

 methods of naval communications available, those 

 utilized most commonly are radiotelegraphy, 

 radioteletype, and radiofacsimile. 



Precedence of Message 



Precedence indicates to communications per- 

 sonnel the relative order in which a message 

 should be handled and delivered, and the rela- 

 tive order in which the action officer should 

 note its contents. Precedence is assigned by 

 the originator on the basis of the message con- 

 tent and how soon the addressee must have it. 

 Because precedence begins as soon as the mes- 

 sage is drafted, the originator and releasing 

 officer should handle the message with the same 

 speed they expect from communications person- 

 nel. 



No message should be given higher prece- 

 dence than that which will assure its reaching 

 the addressee in time for action. Unfortunately 

 for communications efficiency, this rule is all 

 too often disregarded. Originators should be 

 reminded by communicators that misuse of pre- 

 cedence tends to destroy the value of all pre- 

 cedence designators. 



Procedure signs (or prosigns) are single or 

 multiple letter groups which convey in standard 



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