116 



BELL SYSTEM TECHNICAL JOURNAL 



\ 68 KC ; FILiERS 



Fig. 5 — Pilot supply circuit. 



Transmission Performance 

 In general, the performance requirements set down as objectives in 

 the development of this system were based on the assumption that 

 five carrier links operating in tandem and over a 4000-mile circuit 

 should give satisfactory, high-grade service. 



< z 



us < 



1 o 



> z 



0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6 

 FREQUENCY IN KILOCYCLES PER SECOND 



Fig. 6 — Channel frequency characteristics. 



