Threshold circuit for radar video signals

摘要

For a threshold circuit for radar video signals the radar coverage is divided into zones constituted by azimuth sectors and range rings, the zones being subdivided into cells formed by radar scans and range quants. The threshold circuit contains a first cell-averaging circuit (1) for determining the average echo strength in each zone pertaining to the azimuth sector that has been scanned by the radar beam. A first zone-averaging circuit (5) is connected to the first cell-averaging circuit (1) for determining from (1) the last established average echo strength of a zone, (2) the average echo strength of said zone as established after the previous scanning of the relevant azimuth sector by the radar beam, and (3) the average echo strength of zones adjoining in azimuth and range, a new average echo strength of the zone. From this new average value a threshold level is derived, which threshold level is applied to a gate circuit (10) to pass the video signals received in the individual cells of the relevant zone if said video signals exceed the threshold level.