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was made to use existing standard types of equipment as far as possible. 

 The three telephone channels are now obtained by an adaptation of 

 carrier apparatus ordinarily ^ used for long-distance transmission over 

 open-wire lines. 



The six frequency bands (one for each direction for the three chan- 

 nels) are allocated as shown in Fig. 7. A d-c. telegraph channel is 

 also indicated. This figure likewise shows the frequency allocation 

 of the one telephone and four telegraph channels (three carrier and 



Fig. 4 — ^Shore end (core not lead covered) intermediate, and deep sea 

 types of cable. 



one direct current) now carried over each of the three older cables. 

 It will be noted that the band width of the new telephone channels is 

 considerably greater than that of the old ones, thus furnishing higher 

 quality speech transmission. In addition, a considerable range of 

 frequencies remains unused on the new cable. This range may be 

 developed when additional message telephone, broadcasting, or 

 telegraph facilities are needed. 



In adapting the existing type carrier apparatus for operation over 

 the new cable, the problems consisted chiefly in (a) providing for satis- 

 factory transmission over a circuit of considerably higher attenuation 

 than the apparatus was originally designed for and {b) providing the 



'"Carrier Systems on Long Distance Telephone Lines," Affel, Demarest and 

 Green, A. I. E. E. Transactions, Vol. 47, p. 1360, 1928. 



