AN IMPROVED THREE-CHANNEL CARRIER TELEPHONE SYSTEM 55 



and is then used to actuate a regulating mechanism. Changes in the 

 Hne transmission at this frequency are indicative of the changes at 

 all frequencies and the regulator functions to maintain a nearly 

 constant output level in all three-channel bands. 



LOW CHANNEL- 20. 7 KC. CARRIER 



i i I ' I I I I 1 I I 1 L 1 1 



zu 



?^ 

 u. 

 u 

 Ol- 



5s: 



10 15 



DAY or MONTH 



20 



25 



30 



Fig. 5 — Chart showing regulation for a period of one month on 

 system with one repeater. 



