GB729239A - Improvements in radar systems - Google Patents

Abstract

729,239. Radar. MURPHY RADIO, Ltd. Sept. 21, 1953 [Sept. 19, 1952], No. 23628/52; Class 40 (7). In a radar having a stroke pulse generator and a stroke pulse drift controller, the rate of drift of the stroke pulse is related to the repetition frequency of the transmitter. The pulse generator and transmitter 1 of the radar may be associated with a strobe pulse generator 2 of known type providing a gating pulse at a time after the pulse from unit 1 dependent on the condition of the Miller integrator associated with valve 3. The anode-grid capacitor 5 of this integrator is coupled through resistor 6 to diode 7 and short negative pulses simultaneous with the transmitted pulse are fed over capscitor 8 to the cathode of this diode. The voltage at the integrator anode therefore rises by a small amount every time a pulse is transmitted and the interval between the transmitted pulse and the strobe pulse is correspondingly increased. The rate of drift of the strobe pulse is thus made dependent on the transmitter repetition frequency. When the strobe pulse drifts into coincidence with an echo signal received by receiver 9, a positive output pulse is generated by gate circuit 11 which is passed by capacitor 12 and diode 13 and fed to capacitor 9 to set back the strobe pulse in the opposite direction to its normal drift. With full coincidence the setting back is arranged to sufficiently exceed the advance caused by the pulse from the transmitter to ensure that the stroke will follow the echo signal even if the object causing it is changing range in the opposite sense to the normal pulse drift and not every transmitted pulse produces an echo signal. In addition, the output of the gating circuit (or of part of it using an auxiliary wide stroke) is used to reduce the repetition frequency of the radar when the stroke locks on to an echo. For this purpose an output is fed from the gate circuit to a relay 16 serving to modify the circuit of unit 1 and reduce the repetition frequency. Thus when the radar is used in conjunction with a responder beacon the demands made by it on the beacon time can be considerably reduced once the initial locking on has taken place and the beacon enabled to operate effectively with a larger number of interrogating devices. Specifications 690,480 and 718,038 are referred to.