4 THE BELL SYSTEM TECHNICAL JOURNAL, JANUARY 1957 



merged repeaters than at present. This will make possible a further 

 widening of the transmission band which could provide for more tele- 

 phone circuits with accompanying decrease in cost per speech channel 

 or the widened band could be utilized for television transmission. Much 

 work, however, is yet to be done to mature the transistor art to the level 

 of that of the thermionic electron tube and thus insure the constancy of 

 characteristics and long trouble-free life that this transatlantic service 

 demands. 



The present transatlantic telephone cable whose technical properties 

 are presented in the accompanying papers, however, gives promise of 

 large reduction in costs of transoceanic communications on routes where 

 the traffic justifies the provision of large traffic capacity repeatered 

 cables. The thirty-six, four-kilocycle channels which each cable of the 

 two-way system provides, are the equivalent of at least 864 telegraph 

 channels. A modern telegraph cable of the same length without repeaters 

 would provide only one channel of the same speed. The first transat- 

 lantic telegraph cable operated at a much slower speed, and transmitted 

 only three words per minute. The greater capacity of future cables will 

 reduce still further the cost of each communication circuit provided in 

 them. Such considerations point to the economic attracti\'eness, where 

 traffic potentials justify it, of providing broad band repeatered cables 

 for all telephone, telegraph and teletypewriter service across ocean 

 barriers. 



The new transatlantic telephone cable supplements the service 

 now provided by radio telephone between the European and North 

 American Continents. It adds greatly to the present traffic handling 

 capacity of this service. The first of these radio circuits was brought 

 into operation between London and New York in 1927. As demands for 

 service have grown, the number of circuits has been increased. We are, 

 however, fast approaching a limit on further additions, as almost all 

 possible frequency space has now been occupied. The submarine tele- 

 phone cable has come therefore at an opportune time; further growth 

 in traffic is not limited by traffic capacity. 



Technical developments over the years by the British Post Office and 

 Bell Telephone Laboratories have brought continuing improvement in 

 the quality, continuity and reliability of the radio circuits. The use of 

 high freciuency transmission on a single side band with suppressed 

 carrier and steerable receiving antenna are typical of these developments. 

 Even so, the route, because of its location on the earth's surface, is 

 particularly susceptible to ionospheric disturbances which produce 

 quality deterioration and at times interrupt the service completely. 



