56 



BELL SYSTEM TECHNICAL JOURNAL 



Still another effect of the transmission delay is to somewhat slow 

 up and perhaps otherwise interfere with conversations due to the 

 delay which is added to the ordinary time elapsing between question 

 and answer. F"or example, if a cable circuit is 5,000 kilometers long 



Fig. 45 — Thirty 4-wire repeaters and associated testing equipment. The repeaters 

 are arranged in groups of 3 with a minimum of cabling, each group being associated 

 with a phantom circuit and its 2 side circuits. 



and the voice waves travel 30,000 kilometers per second, the time 

 required for the waves to travel from one end of the circuit to the 

 other is }/^ second and to make a complete round trip, 3^3 second. 

 This }y^ second delay is evidently added to the ordinary time which 

 elapses between question and answer. In the United States cable 

 connections somewhat longer than 5,000 kilometers will be used in 



