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BELL SYSTEM TECHNICAL JOURNAL 



receiving station on its own side of the ocean, thus bringing in the 

 possibility of local oscillations and distortions. 



For either the long or short waves then it is very advantageous, in 

 fact practically necessary, to employ switching devices actuated by 

 the voice waves themselves to prevent the effects just stated. In this 

 diagram you will note drawn so as to involve the wire connections both 

 to the transmitting and the receiving station at each end a rectangle 

 which is labeled " voice-actuated apparatus. " This is so arranged 

 that when there is no transmission on the circuit the wires connecting 

 to each of the transmitting stations are short-circuited, making both 

 transmitting stations inactive. Speech coming in then at one of the 

 ends from a telephone subscriber operates a relay which opens the wire 

 circuit to the transmitting station at his end and at the same time 

 short-circuits the receiving path at the same end. 



One interesting phase of this voice-operated switching mechanism 

 is the employment of a delay circuit. At the New York terminal of 

 the circuit, when the voice currents reach it from some distant sub- 

 scriber and after these voice currents have actuated the switching 



TRANSOCEANIC CIRCUIT POWER LEVELS 



i,ooaooo,ooo 



loaooaooo 



io,ooaooo 



1000,000 

 100,000 



laooo 



1,000 



001 



jooqi 



X)00,OI 

 000,001 

 .0000001 

 jOOCOOOOI 



Fig. 14 — Diagrams showing energy levels 



mechanism noted above, they pass into an artificial line down which 

 they travel, are reflected and travel back to the sending end of the 

 artificial line. In this way the voice waves are allowed to idle away 



