Video Processor for Transponder Pulses

Abstract

Circuit detects interrogation signals from air-traffic-control station and determines whether transponder of airplane should respond. Circuit examines relative magnitudes of first two pulses in three-pulse sequence of interrogation signal. On basis of relative magnitudes, circuit decides whether main lobe of interrogating radar beam is received (response should be generated) or only side lobe received (and interrogation ignored). Circuit simple and inexpensive.