ADVANCES IN CARRIER TELEGRAPH TRANSMISSION 



183 



channels is finite, some infiltration of undesired frequencies takes place. 

 Thus if a given channel is spacing and the adjacent ones marking, some 

 small fraction of the flanking carriers will find their way into the idle 



a NOMINAL POWER 



b I CHANNEL MARKING 

 OTHERS SPACING 



C I CHANNEL MARKING 

 OTHERS OPERATING 



C ALL CHANNELS MARKING 



I CHANNEL SPACING 

 OTHERS OPERATING 



I CHANNEL SPACING 

 OTHERS MARKING 



e AMBIENT NOISE 



(ALL CHANNELS SPACING) 



POWER TRANSMITTED PER TELEGRAPH CHANNEL IN dbm 



Fig. 11 — Interference in cable circuits. 



channel. Furthermore, if a channel is in operation, the sending filter 

 does not completely suppress the sideband components lying outside 

 the band assigned to it, and these pass freely through the receiving 

 filter of nearby channels. Unlike modulation, the effectiveness of 



