398 



BELL SYSTEM TECHNICAL JOVRXAL 



filter will contain a quantizinjj; disturbance not shown in (e) which was not 

 present in the input signal. 



A signal that uses regularly occurring ON-OFF pulses can be "regener- 

 ated" and repeated indefinitely without degradation. A pulse can be 

 "regenerated" by equipment which transmits an undistorted pulse provided 

 a somewhat distorted pulse is received, and transmits nothing otherwise. 



BINARY NUMBER 



I I I i I I I I I i 



DECODED NUMBER 



WEIGHTED EQUIVALENT 



16 i 8 ; 4 ; 2 1 1 



I i I ; 1 I I 



J — L 



16 ; I 1 2 ; 



n =^ 



Fis;. 2 — Binar\' and decimal equivalents. 



Thus, the received signal at the output of the final decoder is of the same 

 quality as one produced by a local monitoring decoder. To accomplish 

 this result, it is necessary, of course, to regenerate the digit pulses before 

 they have been too badly mutilated by noise or distortion in tlie transmission 

 medium. 



The regenerative ])roperty of a quantized signal can be of great importance 

 in a long repeated system. I'"or example, with a con\cntional system each 

 repeater link of a lOO-link system must huNc a signal-to-noise ratio 20 db 



