THE FUTURE OF TRANSOCEANIC TELEPHONY 9 



signals except those arriving over one path. By providing additional 

 antenna directivity it makes possible operation in periods of reduced 

 signal strength, though it does not eliminate circuit interruptions at timesof 

 very severe disturbance. Single-sideband transmission and the musa are 

 now in regular use on the New York-London telephone circuits. 



The combination of modern short and long-wave technique now pro- 

 vides across the Atlantic a telephone service which is acceptable for general 

 commercial use, though admittedly of somewhat variable quality. Com- 

 plete interruption of short-wave service with inadequate long-wave service 

 to fall back on, remains the most serious limitation. Neither the reliability 

 nor the quality of transatlantic telephony is yet up to the standards of a 

 well-constructed and well-maintained wire line. 



As matters stand today the short-wave bands, carefully used, could be 

 made to handle a very substantially increased load. The long-wave band 

 is much more restricted yet it is on the long waves that we now depend 

 when short waves fail, as they do at times. Marked improvement in 

 reliability of present systems, or some altogether new and independent 

 system, is needed to provide an alternative group of circuits to insure 

 availability of service as users come to rely on it in their business and social 

 intercourse. This is one of the important factors that led to the develop- 

 ment of the transatlantic telephone cable. 



To predict the future development of transoceanic telephony is pre- 

 sumptuous, to say the least. So rapid has been the advance in the art of 

 communication and so revolutionary have been the discoveries in this field 

 that one is quite unwarranted in setting any limits to the progress that may 

 be achieved. However, there are some developments that have progressed 

 far enough in the laboratory to discuss with reference to their early applica- 

 tion; also there are pertinent indications as to the future of transoceanic 

 telephony apparent from consideration of developments which have occurred 

 in long-distance overland telephony. 



Perhaps the most significant recent development in land-line telephony 

 is that of broad-band transmission over open wires, cables and coaxial 

 conductors. Broad-band transmission means the treanmission by carrier 

 methods of a considerable group of telephone bands on closely spaced 

 channels. Over open-wire lines and over pairs in lead-covered cables, 12 

 telephone bands spaced at 4000-cycle intervals are commonly transmitted 

 in a group occupying a total band width of 48,000 cycles. With coaxial 

 conductors, the band has been increased to 2,000,000 cycles giving frequency 

 space for some 500 telephone channels and it may be expanded still further 

 when more channels are required. 



The application of broad-band methods to transoceanic radio telephony 

 may be anticipated with some confidence. To achieve it requires broad- 



