Research On SAR Motion Compensation Based On Received Signals

Synthetic aperture radar(SAR) is a new type of radar system developed since 1950's. It breaks through the resolution limitation imposed by real aperture. With pulse compression techniques, two-dimensional high resolution imaging to distant targets can be realized. This thesis studies SAR motion compensation which based on the received signals.Chapter 1 explains the basic idea of the imaging radar. the history, the latest development and the applications of imaging radar. Auto-focus technology is also reviewed.Chapter 2 is divided into two main parts. First part introduces the source and classification of phase error, discusses phase gradient auto-focus arithmetic, brings forward its flow chart and process chart, finally checks its validity by realistic scene data. Second part analyzes the limitation of 2DPGA arithmetic , uses FFT rather than DCT to solve Poisson's equation confronted with in the step of phase unwrapping, filters out second order error before 2DPGA processing, selects quality scatters out of the same large pool(rectangular window) .With ameliorations above we can speed the estimation convergence by no iteration. The arithmetic achieves near-convergence focusing quality with nearly instantaneous delay.Chapter 3 amply analyzes Doppler frequency estimation based on image cost function, and present ameliorations, combines the original algorithm with FA, LBFS, genetic algorithm, bound function algorithm, branch and bound algorithm and compares their results.