THE N-1 CARRIER SYSTEM 



29 



ing repeaters there may be. The arrows at "a" and "b" show the line change 

 expected for extreme ranges of ambient temperature for 8 miles of 19-guage 

 toll cable. The group terminal regulators have characteristics about like 

 those of the HL repeater. It can be seen that it would take a most extra- 

 ordinary set of line conditions to require the channel regulator to com- 

 pensate for as much as ±5 db change at its input. Despite the doubling of 



5cn 



0.5 1.0 1.5 2.0 2.5 3.0 



FREQUENCY IN KILOCYCLES PER SECOND 



3 

 O 



a. 

 u 4 



z 



m 



O 5 

 Z 

 < 

 X 

 «-> 6 



5 6 7 8 9 10 11 12 



1000 CYCLE OUTPUT AT "O" LEVEL IN DECIBELS 



ABOVE 1 MILLIWATT 



Fig. 16(a) — T)^ical channel net loss frequency characteristic, 

 (b) — Typical channel limiting characteristics. 



circuit variations by the expandor circuit, Fig. 14 indicates that the overall 

 channel net loss can be expected to stay within about d=2 db. 



Figure 15 shows the speed with which the thermistor regulator in the 

 repeater restores the output to normal when subjected to a line change. 

 An increase of input from the line of 6.5 db, for example, requires a 5-minute 

 wait for the output to get within .25 db of its final value. The regulator 

 operates more slowly on decreasing line input. It is essential that the regula- 

 tor move rather slowly to avoid false regulation on accidental short-dura- 

 tion line hits. 



