TRANSISTOR BINARY PULSE REGENERATOR 



1073 



regenerating a noise-dictated random code having the same pulse 

 density expected of a normal PCM signal. The results are shown on 

 Plate III(c). After passing through two repeaters the jitter has been 

 substantially removed as shown by the sharp vertical lines marking the 

 pulses. The thickening of the horizontal lines are produced by transients 

 produced by low frequency cut off distortion. In all these photographs 

 the oscillograph synchronization was obtained from the code generator. 



3.2 Possible Effects of Line Temperature Variations 



The gain and phase characteristics of a particular wire transmission 

 line is a function not only of its length but of temperature as well. To 

 the first order approximation the effect of an increase in temperature 

 may be considered as caused by an increase in the length of the line. 

 In order to better understand the effect of temperature change on re- 

 peater performance the following steps were taken; The repeater was 

 adjusted for optimum performance with 2.3 miles of line between it and 

 the preceding repeater and then the length of the connecting transmis- 

 sion line was decreased by about 25 per cent. It was found that for the 

 same interference on the input of the repeater no difference in the 

 performance of the repeater was observed. Plate IV shows a fixed code 

 signal after it has traversed 2.3 miles of equalized cable. Superimposed 



TWO-PULSE CODE 



lb) 



FOUR-PULSE CODE 



(C) 

 RANDOM CODE 



Plate III — (a), set code having 2 pulses out of possible 8; (b), set code having 

 4 pulses out of possible 8; (c), random code having an average of 4 pulses out of a 

 possible 8.1 (a and b), input signal plus interference; 2 (a and b), regenerated 

 output of 1; 3, expanded section of 2; 4, output of 2nd repeater; 5, output of 3rd 

 repeater; 6, output of 4th repeater. 1(c), input signal alone; 2(c), imput signal 

 plus interference. 



