ADVANCES IN CARRIER TELEGRAPH TRANSMISSION 



187 



circuit during normal operation, since the power transmitted over the 

 circuit then varies fortuitously over a range of 10.8 db for a 12-channel 

 circuit and 13.8 db for a 24-channel system, depending on the number 

 of channels which happen to be marking simultaneously. 



A 



2 4 6 8 10 12 14 16 18 20 22 24 26 



NOMINAL POWER AT REPEATER OUTPUT (DUE TO 12 MARKING CHANNELS) IN dbm 



uj 2.0 



1.5 



2295 

 FREQUENCY ON LINE IN CYCLES PER SECOND 



4335 



Fig. 13 — Crowding. H44 circuits. A. Relative crowding vs. power. 12 chan- 

 nel system. Channel No. 5 (1105 cycles per second). B. Crowding vs. frequency. 

 24 channel system. Total power at repeater output increased from 2.2 to 9.2 dbm. 



