THE L3 SYSTEM — TELEVISION TERMINALS 



935 



coupling coefficient can cause a reflection coefficient of 1 per cent in 

 certain sections at the frequency of 180° phase shift. 



2. The Q factors of both inductors are adjusted to be equal in each 

 section. 



3. The values of the capacitors are modified to compensate for the 

 presence of the parasitic capacitances associated with the shunt arm, 

 Fig. 11. 



The measured insertion loss characteristic and phase shift deviation 

 from linear phase slope for one model of the transmitting filter and delay- 

 equalizer is shown on Fig. 15. This has been reduced to video frequency 

 to show the detailed residual distortion which results from the addition 

 of the vestigial lower and upper sideband. The delay equalization is 

 maintained for about 200 kc above the loss cut-off to provide for at 

 least 30-db insertion loss at frequencies where the delay distortion 

 becomes large. Without this precaution the transient response is charac- 

 terized by a severe "cut-off ring" distortion which is a slowly damped 

 oscillation at cut-off frequency generated by high frequency signal 

 components. 



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 lij 



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0.5 



1.0 1.5 2.0 2.5 3.0 3.5 4.0 



FREQUENCY IN MEGACYCLES PER SECOND 



4.5 



5.0 



Fig. 15 — Measured pass band performance of a trial model of the transmitting 

 filters and equalizer. 



