626 



BELL SYSTEM TECHNICAL JOURNAL 



In the figure it will be noted that trace (a) shows a perfect signal with 

 the arrows denoting the sensitive points for receiving each pulse located 

 directly at the center of each of the pulses 1 to 5. This is a normal 

 adjustment for a receiving distributor which, without change of this 

 adjustment, must be able to tolerate the distortions of various kinds 



PERFECT SIGNAL 



MARKING BIAS 



SPACING BIAS 



DISTORTIONS OTHER 

 THAN BIAS 



SENDING DISTRIBUTOR 

 TTT-lej % FASTER THAN 

 ' '-/RECEIVING DISTRIBUTOR 

 -.SENDING DISTRIBUTOR 



F-^>^\V:\V^-v^: \ 5.9 "/a SLOWER THAN 



) RECEIVING DISTRIBUTOR 



Fig. 5 — Effect of distorted signals on reception. 



experienced in service without failure to receive and properly identify 

 each pulse as a No. 1, 2, 3, 4 or 5 pulse. The other traces illustrate 

 certain types of distortions which may be experienced and the condi- 

 tions existing for their proper reception with this adjustment. These 

 traces will now be explained on a purely theoretical basis assuming an 

 ideal receiving machine without mechanical or other imperfections. 



Trace (b) shows the conditions in case of 25 per cent "marking bias" 

 in the received signals; that is, each marking pulse has been lengthened 



