On The Study Of Airborne Synthetic Aperture Radar Imaging And Autofocus Algorithm

Nowadays, more and more high resolution is required in widely used SAR field. It.seems very impoftant to develop high-resolation and ultra-high-resolutionairbome SAR. However, along wth the requirement of the high-resolution, manyproblems come fOrth, the core of Which is to eliminate the phase errors brought bythe motion errors.The aim of this dissertation is to find an effectively way to comPensate the motionerrors. At first, we stlldied the SAR and its imaging theory, and accomPlished the..imaging of the realistic airbome SAR data using the Range-Doppler algorithm onthe basis of analyzing SAR imaging theory. The fairly well imaging resultsindicate that the Range-Doppler algorithm is effective on the condition of side-looking withoat squillt. After that, we discussed some sources of motion errorsand introduced the influence of phase errors to imaging, and came to anconclusion that phase errors is one of the dominating reasons decreasing imagingquality In this dissertation, the experiments of point target imaging were done toexplain the problem aroused by quadratic and cubic phase errors influent theimaging. In order to effectively eliminate or reduce the influence of motion ermrsto imaging, thIee representative autofocus a1gorithJns were discussed, i.e. MaPDrift, Shift and Correlation, Phase Gradient Autofocus. Poini target simulationwas also carried oul. Different amofocus algorithms were used to compensate themotion errors of airbome SAR data, their merits and defects were representedaccording to the comparison and analysis of the imaging results.Based on the above works, a comparatively integrated program was developed.The program include the imaging process of SAR original echo data, theautofocus algorithm and multi-looks technique of the SAR image post-treatment.