START-STOP RECEIVERS 



219 



be larger; in negative skew, M£ and 5£ displacements tend to be larger. 

 The magnitude of the skew is defined as the difference between the mag- 

 nitudes of the fortuitous effects on space-to-mark and mark-to-space 

 transitions. 



Figure 3 showed the bias parallelogram of a receiver which had a local 

 margin of 10 to 90. Figure 5 shows the bias parallelogram of a perfect 



100 



-50 +50 



(A) PERFECT RECEIVER 



-50 +50 



(B) +10% BIAS 



-50 +50 



(C) -10% CIAS 



-50 +50 



(D) +5% SKEW 



100 



+50 



:) -5% SKEW 



-50 +50 



(F) 5% FORTUITOUS 



Fig. 5 — Effect of internal distortion on bias parallelogram. 



receiver and illustrates how the components of internal distortion affect the 

 shape of the bias parallelogram. The skewing of the corners of the par- 

 allelograms shown in Fig 5(D) and (C) led to the use of the term "skew" 

 for this effect. 



In telegraph transmission systems skew may be caused by the effect of 

 interference on a wave which has different slopes during mark-to-space and 



