Ice patrol in 1949 will in all probability consist of only the synoptic 

 surface weather observations by the surface patrol vessels and the 

 oceanographic vessel, omitting all upper air observations. 



COMMUNICATIONS 



In 1948 the following daily schedule of ice broadcasts to shipping was 

 maintained from 15 March until 7 July. Each broadcast was preceded 

 by a general call on 500 kilocycles after which the transmitting station 

 (Radio Argentia, NWP) announced the NIDK ice bulletin with the 

 operating signal to shift to 480 and 8,100 kilocycles. After shifting to 

 these frequencies there followed a 30-second period of test signals to 

 permit receiver tuning. The ice bulletin was then broadcast twice, the 

 first transmission being made at 15 words per minute and the second 

 transmission at 25 words per minute, with a 2-minute interval between 

 transmissions. 



Time (G.c.t.) Frequency (kilocycles) Emission 



0118 480 A2 



0118 8,100 Al 



1318 480 A2 



1318 8,100 Al 



The above-mentioned times of transmission have been selected so that 

 each bulletin would contain the maximum amount of recently received 

 information, would be transmitted with the least number of breaks due 

 to silent periods, and would be completed during the hours when the 

 operators on single-operator ships were on duty. The morning broadcast 

 is timed so as to include a digest of the reports which increase in number 

 during the first few hours after daylight, with its improved visibility, 

 and the evening broadcast, so as to include the results of any aerial recon- 

 naissance made during the day, since the planes normally return to base 

 shortly before dusk. 



Each bulletin followed the same general pattern. The bulletin started 

 with the position(s) of the southernmost known ice. Following this, the 

 most recent ice information was given first, listing the ice from south to 

 north and east to west. As in previous years, a distinction was made 

 between ice sighted by units of the International Ice Patrol, i. e., the 

 surface vessel on patrol, the oceanographic vessel, or one of the ice patrol 

 aircraft, and that sighted by all other units. The former was listed as 

 ice sighted and the latter as ice reported. To avoid confusion during 

 periods of poor radio reception, all reports of obstructions such as buoys, 

 logs, mines, etc., were placed at the end of the bulletin. 



The importance of communications to the success of the International 

 Service of Ice Observation and Ice Patrol cannot be overly stressed. In 

 the past, criticism and comment from maritime agencies and vessels 

 making use of this service has resulted in increased efficiency and use- 



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