704 



BELL SYSTEM TECHNICAL JOURNAL 



The noise suppression device, termed a "codan" (carrier operated 

 device anti-noise) is employed in connection with the receiver which 

 introduces a predetermined high loss into the audio-frequency portion 

 of the radio receiver during intervals when there is no incoming carrier, 

 and insures relatively quiet conditions on the receiving line. When a 

 carrier is received, the codan action removes this loss, allowing the 

 speech with which the carrier is modulated to pass from the receiver 



Fig. 2 — Marine radio compass installed on a trawler. 



