EFFECT OF SIGNAL DISTORTION IN MORSE TELEGRAPHY 279 



value of about 30 per cent and considered the circuit unsatisfactory at 

 about 50 per cent. 



An analysis of the errors made by the operators for values of dis- 

 tortion from 30 per cent to 70 per cent indicated that a large number 

 of errors were due to confusion, as in the case of positive bias. For 

 large values of bias there were some errors which indicated an inter- 

 pretation of dashes as dots, although most of the errors were miscel- 

 laneous interpretations, together with a large number of letters added 

 and omitted. 



100 



96 



,92 



"He a 



"y 



Lie ht" 



8& 



64 



80 



Effect of 

 "Positive Characteristic Distortion 



ZO 30 40 50 



Per CeotDisbortion 



Fig. 4. 



60 



70 



80 



3. Effect of Characteristic Distortion 



During the tests with positive and negative characteristic distortion, 

 a peculiar effect of moderate amounts of such distortion on the opinion 

 of operators was noticed. In general, operators tend to call a circuit 

 "heavy," "light," or "unsteady." If the amount of characteristic 

 distortion is not large enough to warrant the term "unsteady," some 

 operators may call the circuit "light" while others may call it "heavy." 

 In a few cases the operators stated that the bias changed constantly 

 from one letter or word to another. The latter characterization is 

 probably the more accurate and accounts to some extent for the differ- 

 ence of opinion. When the amount of distortion becomes large enough 

 so that the operators consider a circuit "unsteady," they also call it 

 "light" in most cases. 



