Fast backprojection algorithm for synthetic aperture radar

We introduce a new algorithm for time-domain backprojection of synthetic aperture radar (SAR) data. The algorithm reproduces images generated by standard backprojection pixel-for-pixel to any required tolerance, but it runs roughly /spl radic/N times faster for an N by N pixel image. Fast backprojection retains the advantages of standard backprojection: perfect motion compensation for any flight path, low artifact levels, unlimited scene size, perfect focus for arbitrarily wide bandwidths and integration angles, and strictly local processing (i.e., pulses can be processed as they are collected without along-track buffering or corner turns). The new algorithm also makes it possible to store the image in progress on disk (rather than in memory) with only a mild penalty in processing speed.