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BELL SYSTEM TECHNICAL JOURNAL 



at one end, the steady state will not be established within the network 

 until after some lapse of time, whereas it occurs at the terminating 

 resistance instantaneously. This property is, of course, to be ex- 

 pected from its steady-state characteristics. 



^ 7 



2Rt/L/2 

 Fig. 10 — Indicial voltages in distortionless network. 



It may be added that such networks would still give complementary 

 results if separated for any purpose by a symmetrical line in a circuit 

 which is terminated at each end by a resistance R and which has an 

 e.m.f. applied through one of the resistances. The separation of the 

 two complementary networks under these conditions would result in 

 the same current being received by the terminating resistance as when 

 both networks are together at one end, where it is known the networks 

 would produce no distortion. This follows immediately from the 

 reciprocal theorem. For by it we readily see that the same current 

 would be transmitted to the input terminals of the complementary 

 receiving network whether the first network was at one end or the 

 other. (These two cases are equivalent from the standpoint of received 

 current to turning the combined transmission line and first network 

 end for end.) 



4.2. Distortion Correction in Submarine Cable Circuit 

 The following illustration shows the improvement which can be 

 made in the shape of the arrival voltage at the end of a long submarine 

 cable circuit by distortion correction at the very low frequencies only. 

 Such an improvement would increase the speed of building up of d-c. 

 telegraph signals and hence allow a greater speed of signaling. 



