42 



THE BELL SYSTEM TECHNICAL JOURNAL, JANUARY 1956 



newer double-gated pulse generator, while the pulse on the right was 

 produced by the regenerative pulse generator. It can be seen that they 

 appear to have about the same pulse width and shape. This is partly 

 due to the fact that the video amplifier bandwidth is not c^uite adequate 

 to show the actual shape, since in both cases the pulses are slightly 

 shorter than can be correctly reproduced through this amplifier. The 

 ripples on the base line following the pulses are also due to the video 

 amplifier characteristics when used with such short pulses. 



4. RESOLUTION AND MEASURING RANGE 



Fig. 5 shows a piece of equipment which was placed between the pulse 

 generator and the receiver to show the resolution which can be obtained. 

 This waveguide hybrid junction has its branch marked 1 connected to 

 the pulse generator and branch 3 connected to the receiver. If the two 

 side branches marked 2 and 4 were terminated, substantially no energy 

 would be transmitted from the pulser straight through to the receiver. 

 However, a short circuit placed on either side branch will send energy 

 through the system to the receiver. Two short circuits were so placed 

 that the one on branch 4 was 4 feet farther away from the hybiid junc- 

 tion than the one on branch 2. The pulse appearing first is produced l)y 

 a signal traveling from the pulse generator to the short circuit on branch 

 2 and then through to the receiver, as shown by the path drawn with 

 short dashes. A second pulse is produced by the signal which travels 



BRANCH 

 2 



SHORT 

 CIRCUIT 



BRANCH 



FROM 

 PULSER 



TO 

 RECEIVER 



FIRST PULSE PATH 

 SECOND PULSE PATH 



SHORT 



CIRCUIT 



DOUBLE-GATED PULSES 



REGENERATIVE PULSES 



Fig. 5 — W;iv(!guicle hyhriil ciicuil- uscxl to demonstrate resululion of milli- 

 microsecond pulses. Trace photographs of pulses from each type of generator ;iie 

 shown. 



