Patent ID: 6236351
Filing Date: 2001-05-22
Classification: G01S,H01Q,Y02A

Abstract:
A method, performed on an aircraft, for automatically adjusting the tilt angle of a radar antenna to limit ground clutter to acceptable levels, with the radar antenna scanning a forward field of view within a specified range, said method comprising the steps of:storing a terrain database including terrain cells identified by latitude and longitude intersections indexed by ilat and ilng values, with each terrain cell including a terrain elevation value;determining current location co-ordinate indices of the aircraft;for co-ordinates within the field of view and range, and based on the current location co-ordinate indices, determine minimum and maximum latitude and longitude index values;setting ilat equal to the minimum latitude index andsetting ilng equal to the minimum longitude index;(a) retrieving the terrain elevation at the co-ordinates specified by ilat and ilng from the terrain database;(b) based on the terrain elevation and distance between the current location co-ordinates and the point (ilat, ilng) calculating an elevation angle between a horizontal along the flight path of the aircraft and the terrain elevation point;(c) storing the calculated elevation angle;if ilng is less than the maximum longitude co-ordinate incrementing ilng else;if ilng is equal to the maximum longitude co-ordinate and ilat is less than the maximum latitude co-ordinate incrementing ilat and repeating steps (a), (b), and (c) else;adjusting the antenna to have a tilt angle equal to the elevation angle.