194 



BELL SYSTEM TECHNICAL JOURNAL 



Listening tests over ten carrier links in tandem indicate that the design 

 objectives are sound and that a satisfactory reduction in delay distortion 

 has been achieved. 



8 



FREQUENCY IN KC 

 Fig. 16 — Delay of audio and carrier-frequency equalizers and delay of equalized pro- 

 gram terminal. 



APPENDIX 



For an infinitely long set of charged filaments of the type shown in Fig. 3 

 and located at co = c/2, 3a/2, Sa/2, etc., the insertion loss and phase may 

 be expressed by the infinite-product expansion of equation (1), 



[p^- K- j(n - l)a][p + K+ j{n - ^)a] 



A+i 



'-U 



n-1 [p 

 1 - 



= n 



kn - j{n - \)a\[p - K-\- Jin 



i2( p + kn)Tr/a 

 (In - \)jr 



^)a] 



1 - 



i2{p — kn)Tr/a 



(8) 



(2n - l)7r 

 Expression (8) is a standard form of product expansion and may be written 



A+jB ^ cos j(p + k „)ir/a 

 cos j{p — kn)ir/a 



(9) 



or 



A-\-jB = logcosi(/> + ^Jr/a — logcosy(/> — *„)7r/a (10) 



