The Bell System Technical Journal 



Vol. XVIII October, 1939 No. 4 



Experience in Applying Carrier Telephone Systems 

 to Toll Cables 



By W. B. BEDELL, G. B. RANSOM and W. A. STEVENS 



THE application of carrier telephone systems to toll cable con- 

 ductors, particularly those conductors in existing cables, is 

 expected to become an important means of providing additional long 

 distance telephone circuits. Eight hundred and thirty-seven route 

 miles have been equipped in the United States to date, and 17 twelve- 

 channel systems have been placed in service, providing a total of 

 about 58,000 circuit miles. Late in 1939, 200 additional route miles 

 are expected to be completed which, together with additional systems 

 on existing routes, will add nine systems and about 48,000 circuit 

 miles to the above figures. 



The type of carrier system which has been installed is that described 

 by Messrs. C. W. Green and E. I. Green before the American Institute 

 of Electrical Engineers in 1938, and which is now designated as 

 type K.^ The problems incident to the application of this system to 

 toll cable conductors may be of general interest and it is the purpose 

 of this paper to describe some of these. This description will start 

 at the point where traffic needs have indicated that additional circuits 

 should be provided along a given route and economic and other con- 

 siderations have shown that they should be provided by means of 

 type K cable carrier telephone systems. For specific examples, refer- 

 ence will be made to the New York-Charlotte and Detroit-South Bend 

 projects, in which sections the application of the initial type K carrier 

 systems has been completed. Figure 1 shows the geographical loca- 

 tion of these installations, as well as some of those sections where 

 type K carrier systems will probably be installed in the future. 



^ For references see end of paper. 



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