REGENEKATION OF BINARY MICROWAVE PULSES 



71 



fied by another traveling-wave amplifier and fed back into the loop in- 

 put thus completing the circuit. 



The synchronizing equipment starts out with an oscillator going at 

 approximately 78 kc. A pulse generator is locked in step with this os- 

 cillator. The output of the pulser is a negative 3 microsecond pulse as 

 shown in Fig. 3A. After being amplified to a level of about 75 volts 

 this pulse is applied to the helix of the first traveling-wave tube to re- 

 I duce the gain of this tube during the 3-microsecond interval. Out of each 

 12.8/xsec interval pulses are allowed to circulate for O.S/xsec but are blocked 

 I for the remaining 3Msec thus allowing the loop to return to the quiescent 

 i condition once during each period as shown on Figs. 3A and 3C. 



The S^sec pulse also synchronizes a short-pulse generator. This unit 

 delivers pulses which are about 25 millimicroseconds long at the base 

 and spaced by 12.8/isec, i.e., Avith a repetition frequency of 78 kc. See 

 Fig. 3B. 



In order to simulate a PCM system it was decided to circulate pulse 



CIRCULATING INTERVAL 

 9.8/ZS 



QUENCHING 

 INTERVAL 



-3//S-*| 



(A) GATING CYCLE 



(B) SHORT SYNCHRONIZING PULSES 



--24 GROUPS OF PULSES 





(C) CIRCULATING PULSE GROUPS 



GROUP GROUP GROUP 

 1 2 3 



lOOMyUS 



^ k ^^-o.4;uS-^^ I (D) PULSE GROUPS (EXPANDED) 



■ ' |300M/US| I I 



I 



(E) TIMING WAVE (40MC) EXPANDED 





 TIME 



Fig. 3 — Timing events in the circulating loop. 



