Patent ID: 9110170
Filing Date: 2015-08-18
Classification: G01C,G01S

Abstract:
1. A method for autonomous terrain aided navigation of an airborne vehicle, upon receipt of a request for a terrain navigation update performing the steps of: determining a radar field-of-regard (FOR) search space about the vehicle's flight path from a navigation position estimate and an off-axis capability of the vehicle's multi-channel radar transceiver; searching a terrain elevation database within the search space to select a terrain segment having prominent terrain features that exhibit at least a minimum variation in elevation; computing an off-axis command angle for an antenna main beam to image the selected terrain segment; transmitting at least one RF pulse burst in a 2-35 GHz band in the antenna main beam at the off-axis command angle to illuminate terrain encompassing the selected terrain segment; simultaneously receiving and sampling the RF returns in at least three receive channels to produce a three-dimensional range/Doppler map in which each range/Doppler indexed cell includes a monopulse angle vector (x,y,z) and an intensity Q; converting the three-dimensional range/Doppler map into a three-dimensional image in (x,y,z); and correlating the three-dimensional image and the selected terrain segment in a reference frame of the database to provide a navigation position estimate of the airborne vehicle.