CiRRII-.R-CURREXT COM MU NIC A TION 



643 



As may be seen from Fig. 4, a carrier-equipped cable pro\ides a 

 d-c. telegraph circuit, and one voice-frequency and six carrier-fre- 

 quency telephone channels. The separation of the various channels 

 is efifected by means of electrical filters. Fig. 8 shows the band of 

 frequencies employed for each channel. For the d-c. telegraph this 



SANPEDPXD 



Ch.Jtot 



iimilarko 

 Ch t 



Loaded 



Cable 

 toL A 



j!^nrja 



Ch.2 ko C 

 Similar to 



Ch.l 



Loaded 



L_| 1 TTT — ^?ff^--| j-i 



1 I — t — ow^ — Otft- — I I — 



Cable 

 Hut 



AVALON 



Ch.2ko6 



Similar ko 



Ch.l 



— QrpTKc 



HybCoil 



Swbd 

 CMl^ 



q3=B4Sa— 



Ch.2to6 



Similar to 



Ch.l 



separation is effected at the terminals of the cable as is shown in 

 Fig. 5. The telegraph circuit requires a continuous d-c. path, whereas 

 the telephone channels require the insertion of an inequality ratio 

 insulating transformer at the ends of the cable in order to properly 

 join the 43-ohm grounded cable circuit with the 600-ohm metallic 



