VARIABLE EQUALIZERS 



233 



pression. The particular forms of the functions gsix) and gb(x) are 

 not of great interest. It is important, however, to know their maxi- 

 mum values, which are respectively 0.03 and 0.002. 



FREQUENCY 



Fig. 2 — Diagram to illustrate symmetrical characteristics obtained from the 

 equalizers described in the paper. 



The first two terms in equation (6) can evidently be identified with 

 the quantities appearing on the right-hand side of the ideal regulator 

 equation (1). So far as these terms are concerned, the variable char- 

 acteristics are always strictly proportional to (p. The departure from 

 the ideal is measured by the remaining terms of (6). For ordinary 

 values of (p the series converges so rapidly that only the term in 

 g3{x)<p^ is important. Since the maximum value of gsix) is known an 

 estimate of the distortion is easily made, although some allowance is 

 necessary for the possibilities of "splitting differences" in the design 

 process. With the help of these allowances, however, it turns out that 

 the distortion should be about 0.1 db when the maximum value of ^ 

 is 1 neper, corresponding to a total variation in attenuation of about 



