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 



(a) S 



(b) imym 



(c) -^mym 



(d) mmm 



(e) 



+25 °U 



(f) wwm 



(g)MEMl 



{h)mmm. 



(■oMsm. 



(j)32SSiL 



_E2 



2S3_ 





ML 



iL 



inna. 



im 



im 



-50% ." 



m 



-25 % ' ' 



3^ |4 5 aiui^ 



'' ' ' +25'='/o 



I22L 



23_ 



2L 



ii-26% 



+55° 



-25 "/o 



PERFECT SIGNAL 



MARKING BIAS 



y SPACING BIAS 



DISTORTIONS OTHER 

 THAN BIAS 



W^7^ : 



SENDING DISTRIBUTOR 

 • .. .■ . . .. ■■ .. ii \6.7%FASTER THAN 

 ^■•■■■■•■••.■■•■•■■..••.■JrECEIVING DISTRIBUTOR 



-.SENDING DISTRIBUTOR 

 E-^:^\V:-\v.-v>; ) 5.9 % SLOWER THAN 



> RECEIVING DISTRIBUTOR 



Fig. 5 — Effect of distorted sit;nals 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 



