were all the quantities needed to conduct a quantitative analysis of 

 ice detection. 



When a target had been selected the range was increased until 

 the target disappeared from the radar scope or was out of radar 

 range. The course of the experimental vessel was reversed and 

 the range to the target closed. The maximum range at which each 

 radar detected the target was recorded and after it had once been 

 detected the signal strength of the echo was measured periodically. 

 It was always necessary to obtain the maximum range that the 

 10-cm. radar picked up the target while approaching as it was 

 mounted in front of the mast of the ship. This caused a dead spot 

 directly astern. When the range of the target had closed to roughly 

 1,000 yards, measurements of height, width, and form factor of the 

 target were taken. A photograph of the target was taken when- 

 ever possible in order to verify measurements of target size and to 

 obtain the actual cross sectional area presented to radar energy as 

 the experimental run was made. Also, whenever possible, photo- 

 graphs were taken of the PPI scopes of the two radars so that 

 permanent records of the difference in appearance of targets for 

 the two frequencies would be available. Along with data estab- 

 lishing target size and aspect as well as radar performance, weather 

 conditions existing during test runs were recorded as an aid in 

 examining any variation in performance arising from that source. 

 In addition to the normal shipboard weather measurements, the 

 temperature at the surface and level of the main deck, boat deck, 

 and flying bridge was taken. In this manner it was hoped that any 

 abnormal or subnormal results could be explained. 



Part of this procedure was eliminated during the 1946 season as 

 the personnel situation was so critical that all the measurements 

 desired could not be obtained. The personnel needed for this work, 

 were either missing or inexperienced. Also during the early part 

 of the ice season before shipboard operations were halted com- 

 pletely the turnover of radar personnel on the experimental vessel 

 was very great. This made it a necessity that the electronic re- 

 search officer personally supervise the taking of readings or take 

 most of the readings himself. As a result of this the needed co- 

 ordination between the combat information center (where the 

 radar indicators were located) and the bridge suffered considerably. 

 The data collected during the 1946 season, although not as complete 

 as those collected during the 1945 season, were sufficient to clarify 

 some main points. 



It is desirable that the investigation of the radar detection of 

 floating ice be continued in future years working with the ocean- 

 ographic program. Radar developed very rapidly during the war 

 and has been perfected to a high degree. Nevertheless, many kinks 

 are still to be ironed out. As new developments are made it is pro- 



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