588 



BELL SYSTEM TECHNICAL JOURNAL 



In order to compensate for this effect of varying temperature, a 

 regulating stage is added to the amplifiers at the various regulator 

 stations. Fig. 17 shows how the regulating network stage is added 

 to one of the amplifiers and also shows the general nature of the 

 regulating network circuit. Because of the peculiar and complicated 

 way the transmission loss of the cable circuit varies with temperature, 



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LOSS INTRODUCEC 

 BY LINE 



GAIN INTRODUCED 

 BY REPEATER 



106 206 560 1060 



CYCLES PER SECOND 



2000 



5000 8000 



16 — Attenuation-frequency characteristic of line equalizer and 50 miles of 16-ga. 



B-22 cable circuits. 



a somewhat complicated regulating network is called for. Front and 

 rear views of one of these regulating networks are shown in Figs. 11 

 and 12, the upper panel being the regulating network and the lower 

 the normal amplifier. Fig. 18 shows how the gain characteristic of 

 the amplifier is altered by different steps of the regulating network. 

 This is very closely complementary to the change in cable loss caused 

 by the temperature variations and thus it will be evident that the 

 effects of the temperature changes are largely eliminated. 



Delay Equalizers 



The velocity of transmission through a loaded cable decreases as 

 the frequency is increased toward the cutoff point of the loading. 

 To neutralize this effect, delay-equalizing networks are inserted in the 

 circuit which retard the lower frequencies, thus equalizing the velocity 



