C.IRKIF.R Tl:l.r.l'llO.\y O.V ///(,// rOl.T.IGE I.IM-.S l(.5 



(irriiit wliilt- (■oinmimicKion lutwirii .li, li and C is rarrird on i>\vr 

 cimiits whifh arr idiiiposi'tl of a cirrit-r cirriiil ami a pinsical cir- 

 ruit <)|H'ratiiij; in taiuU-in. W'lu'n in llu- nnrni.il or iiDn-oiK-rali-d 

 conditions, earli of tlu'si' carrier tiTniin.ds is set ii)) lo reci-i\e a sij^nal 

 on fri'(]iifncy Fu lint wlit-n tlie rert-ivcr is reinmed from the swilcli- 

 hiH)k at any station to initiate a call, the carrier tenninai corre- 



Fig. l^ — 110 K.W Coupling Condensers Used for Coupling Carrier Circuit to a 

 110 K.V. Power Line 



sjiondini; to that telepiione is autonialicalK' set up to transmit on 

 frecjuency Fi and receive on frequency F«. When the ringing kc\' is 

 operated, pulses of frequency Fi are sent out and received at all of the 

 other carrier terminals. At the called station these pulses operate 

 a selector relay and ring the l>ell, and when the operator removes 

 his receiver from the switch-hook to answer the call, his carrier terminal 

 is automatically set up to transmit on frequency F> and recei\e on 



