Transatlantic Telephony — the Technical Problem 



By O. B. BLACKWELL 



Synopsis: This paper, which, as it was read, was prefatory' to the joint 

 meeting, describes in rather non-technical terms the engineering problems 

 involved in developing the transatlantic radio trunk by means of which 

 the American telephone system of some 18,000,000 stations can communi- 

 cate with the English telephone system of about 1,500,000 telephones, and 

 also with the telephone systems of other European countries. 



WE wish to give you a picture, necessarily very briefly sketched, 

 of the physical makeup of the transoceanic telephone circuit, 

 why it has been given its present form, and what further improvements 

 are expected as the result of development work now under way. 



The problem in brief is suggested by Fig. 1. A telephone system in 

 America of some 18,000,000 stations, and distances of upwards of 3,000 



Fig, 1 — Map showing U. S. and European telephone systems separated by ocean 



miles. A telephone system in England of about 1,500,000 telephones 

 and the possibilities already partly realized of wire extensions to the 

 other European nations. Three thousand miles of ocean between 

 these two systems. 



The establishment of a connection across the ocean presented two 

 problems. First, the problem of setting up the radio circuit between 

 the United 'States and England and second, the problem of making 

 this radio circuit function as a link between these two widely extended 

 telephone systems. 



Fig. 2 shows the geographical layout of the long wave transoceanic 

 circuit. The course followed by the currents in a connection is as 

 follows: voice currents originating at any substation in America are 



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