DISTORTION CORRECTION 



477 



These results were transformed to give a ladder type network 

 according to Section 2.5 and then incorporated in two of the dis- 

 symmetrical unbalanced full-shunt sections, as shown in Fig. 11. 





n 



Till Ljz 0/3 



V4 



^// -1-12 C/3 



n- 



'^2 



ILz3%B/zitCzz 



■J^2 



\Lz3%RzIt022 



-o *■ 



}' 



■R 



Fig. 11 — Distortion correcting network for submarine cable circuit. 



This transformation gives a different parallel resistance in the series 

 branch, namely, 



Ru' = 2a,RI{\ - flo). (68) 



Here Ru = 8565 ohms. The elements of 221 in the shunt branch of 

 the ladder type were determined from the inverse network relations 



-K11-R21 = L12IC22 = L^s/Cis — Rii'Roi' = i?^. 



Finally combining two resistances which are in series, R^ = R -\- R^i, 

 we have 



R21 = 359 ohms; C22 = 590.3 mf.; 



L23 = .0686 h.; R^/ = .39 ohm; 



and R2 = 58.51 ohms. 



In Fig. 12 are shown the steady-state propagation characteristics of 

 the uncorrected circuit, the correcting network, and the corrected 

 circuit; the latter indicates approximately ideal conditions up to 25 

 cycles per second. 



The improvement in shape of the arrival voltage due to this dis- 

 tortion correction can be seen from Fig. 13 which gives the ratio of 

 indicial to final voltage for both the uncorrected and corrected circuit, a 

 constant e.m.f . being impressed at the sending end at time t = 0. (These 

 were computed from the steady-state characteristics of the respective 

 circuits, using formulae based upon those given by J. R. Carson in 

 B. S. T. J., 1924, p. 563.) The building-up speed has been increased, 

 perhaps fourfold. The arrival voltage for the corrected circuit is 



