Precision focusing algorithms for spaceborne Synthetic Aperture Radar (SAR)

The two-dimensional transfer function is derived from the Synthetic Aperture Radar (SAR) imaging model. Using this expression, the approximations made in the classical range-Doppler and recent chirp-scaling algorithms are examined. An alternative algorithm to the chirp-scaling algorithm is presented. Unlike the chirp-scaling algorithm, this algorithm does not require the transmitted signal to be a linear FM signal and can be easily incorporated into processors using the range-Doppler algorithm. The processing starts with range compressed data rather than from the raw SAR data. Results from processing simulated point targets and the Seasat Goldstone area data show comparable image quality.