A Motion Compensation Method for Low Altitude Airborne SAR

Terrible disorder and serious uncertainty of the low-altitude airborne system’s motion increase the difficulty of SAR (Synthetic Aperture Radar) imaging This paper presents a motion compensation method that brings the RTK data of high precise position information into FFBP (Fast Factorized Back Projection) algorithm to get a high quality SAR image. The coordinates of the defined target area are different from the subimage’s coordinates, how to aim at the interested area under the polar coordinates is presented in order to increase the computation efficiency There are two methods to introduce the position information into FFBP to compensate motion error. One method is to approximate the track to a line, and the origins of the subimages are set on it. Another method set all the origins on the trace curve that bring in higher compensation precision and also higher complexity. Finally two practical results are presented to prove the algorithm’s availability, and also suggest the approximate compensation method (the former one) for efficiency reason when the asymptote of the aircraft’s trace is linear