. The Bell System technical journal . TEM TECHNICAL JOURNAL In this particular radar system the transmitting magnetron is pulsed from afree-running modulator and, therefore, the controlling timing reference pulsefor sweep purposes must be obtained from the modulator circuit. In many-other military radar systems it has proven desirable to time both the trans-mitter modulator and the receiver sweep circuits from a common controllablerepetition frequency source. As shown in Fig. 49, a positive synchronizingpulse as obtained from the transmitting modulator is delivered to the radarreceiver for ran
. The Bell System technical journal . TEM TECHNICAL JOURNAL In this particular radar system the transmitting magnetron is pulsed from afree-running modulator and, therefore, the controlling timing reference pulsefor sweep purposes must be obtained from the modulator circuit. In many-other military radar systems it has proven desirable to time both the trans-mitter modulator and the receiver sweep circuits from a common controllablerepetition frequency source. As shown in Fig. 49, a positive synchronizingpulse as obtained from the transmitting modulator is delivered to the radarreceiver for range timing reference and here applied to the clipper portionof the timing circuit. It was considered here desirable to clip or limit thetiming pulse to gain freedom from timing instability, due to possible ampli-tude variations and to eliminate any possible negative excursions of thetiming pulse which might cause faulty operation of the following multi-vibrator circuit. The multivibrator shown is a modified form of the one- STOP PULSE. l+B — !+B Fig. 49.—Radar Sweep Timing Circuit. Simplified schematic diagram. shot type described previously. The grid of W is normally maintained ata positive potential through its connection to the positive plate supply sourceand accordingly Vi is normally cut off. Upon application of the positive synchronization pulse to Fi and theresultant lowering of the plate potential of Vi the grid of F3 is driven belowcut-off decreasing the voltage drop across the common cathode resistanceand causing ¥> to conduct. This condition will be maintained until thecoupling condenser has discharged sufficiently to permit V^ to again the circuit here described, however, this controlling time constant hasbeen selected to be somewhat larger than tlie total period of the sweep rateand the termination of the sweep timing [julse is accomplished by an externalstoj) pulse applied as shown. This stop pulse is developed in the followingsweep amplifier cir
Size: 2855px × 876px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
