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BELL SYSTEM TECHNICAL JOURNAL 



from which we can measure the total time of rise due to both the 

 aperture and frequency Hmitation. The abscissa is the product of 

 N = lirfc and the time, /. Any one curve serves for a wide range 

 of values of N and T as long as their product is the same. Call the 

 new time of rise r. Then we can plot a relation as on Fig. 16 between 



28 



24 



20 



16 



Nr 



12 



4 6 12 16 20 24 28 



NT 



Fig. 16— Sluggishness due to distortion as a function of the aperture width and 



frequency restriction 



Nt and NT from which we can draw conclusions as to the relative 

 effects of aperture and frequency distortion. 



Below the knee of this curve we have approximately 



Nr = l-K 

 1 



and the frequency cut-off determines the whole distortion. Similarly 

 above the knee 



iVr = A^r + TT 



r = r + 



Vc 



and the controlling influence is that of the aperture. 



