Device for eliminating echoes of fixed or slowly moving targets in connection with airborne radar equipment

摘要

1. A device for eliminating echos of fixed or slowly moving targets in connection with a Doppler type airborne radar emitter-receiver and with an antenna sweeping alternately in one and the other direction, this device being fed from the video outputs of the radar receiver via a terminal E, by the successive sequences corresponding each to an antenna sweep in a given direction, the signals of these sequences being coded in binary words, further comprising memory means (9, 10, 11, 12, 13) for storing binary words, these means containing the signals relating to the latest antenna sweep at address locations defined each by the offset angle G of the radar axis and by the distance D of the target in this direction, and comprising correlation means (16) which receive the contents of the memory means (9, 10, 11, 12, 13) corresponding to the two latest antenna sweeps in this very direction, characterized in that it further comprises address modification means (2) which contain in the memory or receive the value T representing the duration of one antenna sweep, which receive permanently the values relating to the carrier velocity V, to the offset angle G of the antenna axis and to the distance D in which the target corresponding to this value G of the offset angle is located, and which calculates the values of DELTA G=arctg V.T.sin G/D+V.T.cos G and DELTA G=D.[2Root 1+2V.T.cos G/D +V**2 .T**2 /D**2 -1] in order to determine the corrected addresses (G-DELTA G, D+DELTA D) under which the binary words corresponding to the penultimate antenna sweep are registered, the correlation circuit (16) thus furnishing only such signals of the latest sweep which have no corresponding signals at the same address or at adjacent addresses relating to the penultimate sweep in this very direction.