Synthetic aperture radar imaging apparatus and methods for moving targets

Abstract

A synthetic aperture radar (SAR) system may employ SAR imaging to advantageously estimate or monitor a transit characteristic (e.g., velocity, acceleration) of a vehicle, for example a ground based vehicle or water based vehicle. A dual-beam SAR antenna illuminate a moving target with a first radar beam and a second radar beam at an angular offset relative to the first radar beam. Pulses may be transmitted and backscattered energy received simultaneously by the SAR transceiver via the first and second radar beams. A SAR data processor may generate a first image from the first radar beam and a second image from the second radar beam, co-registering the first and second images, comparing the location of the moving target in the first and second images, and estimate a velocity of the moving target based at least in part on the angular offset.

What is claimed is: 
     
         1 . A method of operation of a synthetic aperture radar (SAR) system to estimate the velocity of a moving target, the SAR system comprising:
 a dual-beam SAR antenna, a SAR transceiver and a SAR data processor, the SAR transceiver communicatively coupled to the dual-beam SAR antenna and to the SAR data processor;   the method comprising
 directing a first radar beam to illuminate the moving target in a region on a surface of the Earth by the dual-beam SAR antenna; 
 directing a second radar beam to illuminate the moving target by the dual-beam SAR antenna, the second radar beam at an angular offset relative to the first radar beam; 
 transmitting pulses and receiving backscattered energy simultaneously via the first and second radar beams by the SAR transceiver; 
 generating, by the SAR data processor, a first image from the first radar beam and a second image from the second radar beam; 
 co-registering the first and the second images by the SAR data processor; 
 comparing, by the SAR data processor, the location of the moving target in the first image and the second image; and 
 estimating, by the SAR data processor, a velocity of the moving target based at least in part on the angular offset.