Patent ID: 7479920

Claim:
A method of terrain mapping and/or obstacle detection for aircraft, comprising: (a) transmitting a non-scanning beam that illuminates the terrain and/or obstacles; (b) receiving a Doppler shifted signal that is Doppler frequency shifted by an amount dependent on an angle between a line of flight of the aircraft and scatterers that reflect the transmitted beam; (c) determining the angle from the Doppler frequency; (d) determining the range of at least some of said scatterers; and (e) determining the azimuth and elevation of the scatterers, wherein a backscatter Doppler signal from a terrain cell or object, located on the opposite side of the aircraft's line of flight from a range cell or object of interest and falls within the same range cell and same Doppler filter is suppressed by a null, common to both sum and difference patterns of an antenna receiving said Doppler shifted signal.