SWITCHED NETWORK FOR TIME MULTIPLEX SYSTEMS 1417 



2.0 



Fig. 7 — Computed transmission loss. 



that the signal be sampled at a rate at least tmce as large as its highest 

 frequency component. Since the cutoff occurs at w = 1, the sampling 

 angular freciuency should at least be ec^ual to 2. For illustration purposes 

 we have taken cos = 2.67 and co., = 5 for the angular sampling frequency 

 The value cos = 2.67 corresponds to a cutoff at 3 kc and a sampling rate, 

 of 8 kc. The ratio r/T was taken to be 1/125. The transmission through 

 the switched network as given by the zeroth approximation is shown for 

 both cases on Fig. 7. 



As expected the transmittance of the switched filter gets closer to that 

 of an ordinary filter as the switching frequency increases. 



VIII. THE SUCCESSIVE APPROXIMATION SCHEME 



The ideas involved in the successi^'e approximation scheme are simple 

 and straightforward. One point remains to be settled, namely the con- 

 vergence of the procedure. 



We shall assign a subscript 1 to the correction to be applied to the 



