CHAPTER 7 



COMMUNICATIONS EQUIPMENT AND 

 OPERATIONAL PROCEDURES 



One of the responsibilities of the Aerog- 

 rapher's Mate reaching greater proportions as 

 time goes by is the transmission and receipt 

 of weather data. Even though every Aerographer's 

 Mate in the Naval Weather Service is not di- 

 rectly connected with weather communications, 

 some time during his naval career he will be 

 responsible for the transmission and receipt 

 of weather data. 



It is the purpose in this chapter to present 

 to you as Aerographer's Mates the basic pro- 

 cedures and operation of the weather communi- 

 cations system. 



After weather observations have been taken 

 and entered on the appropriate forms, they must 

 be transmitted to other ships and stations. 

 Rapid communication for weather information is 

 imperative for reliable forecasting, as the 

 weather is often a rapidly changing condition. The 

 weather services use two means of transmission: 

 landline and radio. 



Landline is a network used for transmitting 

 data directly over fixed wire circuits from sta- 

 tion to station or from a control station to 

 a group of stations. The transmission and re- 

 ceipt of printed data over landline circuits are 

 accomplished by the use of teletypewriters. 

 The transmission and receipt of charted data, 

 such as weather maps, over landline circuits 

 are accomplished by the use of facsimile and 

 display equipment. 



Radio is used to transmit and receive data 

 where the use of landline circuits is either 

 impracticable or impossible. Radio is the means 

 by which Fleet Weather Centrals, Fleet Weather 

 Facilities, Fleet Numerical Weather Central, 

 National Weather Service, and FAA activities 

 transmit data to ships and overseas land sta- 

 tions, and vice versa. Data are transmitted by 

 radio on predetermined frequencies and at pre- 

 determined times. 



Printed data are transmitted and received 

 either by radioteletype or by radiotelegraphy. 

 Charted data are transmitted and received by 

 radio facsimile. 



TELETYPES 



The teletypewriter is little more than an 

 electrically operated typewriter. The prefix 

 "tele" means "at a distance." By operating 

 a keyboard similar to that of a typewriter, 

 signals are produced that cause the teletype- 

 writer to print the selected characters (letters, 

 figures, and symbols). The signals can be sent 

 by radio or landline s to cause the characters 

 to be printed or displayed on other teletype 

 machines. 



Because of the increasing variety of teletype 

 equipment installed afloat and ashore, it is 

 impractical to describe every piece of equip- 

 ment you are likely to encounter. The equip- 

 ment discussed in the ensuing paragraphs is 

 therefore representative of the types commonly 

 employed. 



SHORE TYPES 



The two types of teletypes normally employed 

 by weather units at shore activities are the 

 Teletype Corp Model 40, used when the weather 

 unit is a contributing station (fig. 7-1), and 

 the Model 28 R/O (receive only), used for re- 

 ceiving data from various FAA and military 

 circuits. 



Model 40 Teletypewriter 



The Model 40 teletypewriter, provided to all 

 naval weather units contributing to the ADCAD/ 

 OWS system, (Airways Data Collection and Dis- 

 semination/Operational Weather Support), is used 

 for transmitting and receiving weather data on 



123 



