niques employed, it has been the constant aim of the International 

 Ice Patrol to improve and perfect all phases of the communica- 

 tions involved. In 1950, many agencies responded to our long 

 standing request to make criticisms and suggestions for improv- 

 ing the communication procedures, and the United States Coast 

 Guard was able to incorporate most of these recommendations in 

 the communication plan for the 1951 ice patrol season. Some of 

 the more important changes and progressive measures adopted 

 were: 



(1) Relocation of Coast Guard Radio Argentia receivers to a 

 new site to eliminate the blocking previously caused by the 

 proximity of transmitting antennae. 



(2) Changes in times of broadcasts to reduce interference with 

 Navy Radio, Washington (NSS), and Canadian Radio, 

 Halifax, N.S. (CFH) schedules. 



(3) Introduction of new frequencies for ice broadcasts to elimi- 

 nate the interference and skipping encountered in frequen- 

 cies previously used. 



(4) Simultaneous transmissions of both morning and evening 

 ice broadcasts on all three frequencies to eliminate areas 

 of "skip" and give continuous coverage from the station 

 to extreme range. 



(5) Increased power output of transmitters. 



(6) Adoption of 468 kilocycles as an alternate working fre- 

 quency when 480 kilocycles is not readable. 



In 1951 the daily schedule of ice broadcasts to shipping was 

 commenced on March 13 and continued until the termination of 

 the ice season May 18. Each broadcast was preceded by the gen- 

 eral call to all ships (CQ) on 500 kilocycles after which the trans- 

 mitting station, NIK, announced the ice bulletin with the operating 

 signal to shift to 155, 5,320, and 8,425 kilocycles. After shifting 

 to these frequencies, there followed a 30-second delay to permit 

 shipboard operators to tune their receivers. The ice bulletin was 

 then broadcast twice on an automatic keying device with a con- 

 trolled timer, 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. Broadcast times were 

 at 0048 G.C.T. and 1248 G.C.T., with simultaneous transmissions 

 on 155, 5,320, and 8,425 kilocycles. The pattern of the ice bulletin 

 remained more or less unchanged throughout the season. The 

 preamble consisted of a definition of the extreme outer limits of 

 both field ice and icebergs, after which followed a chronological 

 7-day resume of ice conditions, the most recent information being 

 listed first. The usual distinction was made between ice sighted 

 by units of the International Ice Patrol, i.e., ice patrol aircraft 



