A NEW TELEPlIOrOGKAPII SYSTEM 



569 



Delay distortion in H-44-25 cable circuits, which is largely the result 

 of the loading, has been compensated by delay networks consisting of 

 a basic unit correcting for 150 miles of composited 19-gauge side 

 circuit, adjustable in 10-mile steps, and a "mop-up" unit of four 

 sections for more complete compensation. A balanced lattice type of 

 structure was used in the design of these equalizers. Figure 13 



2 

 Z 



< 7.5 



7.1 



1400 1600 1800 2000 2200 



FREQUENCY IN CYCLES PER SECOND 



2800 



Fig. 13 — Delay characteristic of 135 miles of H-44 repeatered and composited side 

 circuit before and after equalization. 



illustrates the application of equalizer units to cable circuits and shows 

 the delay characteristics before and after equalization. Similar types 

 of delay equalizers have been applied to open-wire circuits, in which 

 case it is the equipment located at the repeater stations rather than 

 the line itself which is responsible for delay distortion. The delay 

 equalizers are normally located at terminal and bridging points on 

 the telephotograph network and at some intermediate points such as 

 junctions of open-wire and cable circuits. 



