GB808891A - Test equipment for a radar set - Google Patents

Abstract

808,891. Testing radar systems. SPERRY RAND CORPORATION. July 12, 1957 [July 12, 1956], No. 22148/57. Class 40 (7). Relates to test equipment for radar set in which an echo box.21 is associated with the feed to the radar antenna so as to cause the production of an exponentially decaying echo pulse which may be limited in the receiver video amplifier 24 to provide a pulse B the width of which is a measure of the radar set performance in respect of receiver gain and alignment and transmitter power output. According to a first-feature of the invention, a pulse E is derived from the transmitter trigger pulse A by means of a chain of circuits 27, 28, 29, 31, 32, 33, including an adjustable delay device 32 and is combined with pulse B is network 26. Delay device 32 is adjusted so that, with the radar set operating at the correct level of performance, pulse E is located on the flat top of pulse B at the right-hand extremity. Any reduction of performance reduces the width of pulse B and causes pulse E to ride on the exponential trailing edge. The resulting fall in amplitude of the combined pulses is detected by means of a trigger circuit 34 whose triggering level is adjusted appropriately by a bias control 36 and whose output controls indicating lamps via. a circuit 37. According to a second feature of the invention, trigger circuit 34 is rendered inoperative by means of an inhibiting potential when the level of noise at the output of the receiver exceeds a predetermined amplitude. The output of the video amplifier 24 is applied to a circuit 39 which suppresses signal components of the lower frequency range occupied by radar pulse components and passes the higher frequency components comprised of noise. These components, after amplification are rectified at 38 to provide the inhibiting potential. Fig. 2 (not shown), gives a detailed circuit for units 34, 36, 38 and 39.