Terrain aided navigation using multi-channel monopulse radar imaging

摘要

A terrain aided navigation using multi-channel monopulse radar imaging to provide a navigation position update. The monopulse radar transmits a single RF pulse transmission or multiple quick RF pulse train bursts to generate a monopulse radar image that can be correlated with a digital terrain segment to provide navigation updates when requested. The radar has monopulse and off-axis capability that allows for selection of a terrain segment within the radar's search area that will provide a good terrain correlation. The radar measurements are made on a range/Doppler cell-by-cell basis that includes angle information. The cells in the range/Doppler map corresponding to the antenna main beam return are converted into a high resolution (x,y,z) image and correlated to the selected terrain segment in the data base reference frame to provide an updated navigation position estimate.

主权项

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.