| Motion compensation (MOCO) is an essential part of high-resolution airbornesynthetic aperture radar (SAR) imaging. MOCO is an important research field ofairborne SAR signal processing. This thesis introduces the rationales and theimplementation of airborne SAR MOCO, and then studies the MOCO based on dataprocessing. MOCO based on data processing includes two categories: the one isMOCO for known motion errors and the other is that for unknown ones. This thesismakes some discusses about these two MOCO. In addition, it finishes the softwareand hardware design of real-time MOCO and imaging based on field programmablegate arrays (FPGAs). The thesis is comprised of five main components as follows:(1) Five typical image formation algorithms are studied, which are three algorithmsfor stripmap SAR: range-Doppler algorithm (R-DA), chirp scaling algorithm(CSA), range migration algorithm (RMA), and two for spotlight SAR: polarformat algorithm (PFA) and polar format based overlapped subaperture algorithm(PF-OSA). The rationales and processing steps of these algorithms are introducedin details. Comparison of their applicabilities and performances is made accordingto the quantities of range cell migration.(2) Different types of airborne SAR motion errors are analyzed, which are caused bythe deviations of the antenna phase centre. Since different phase errors havedifferent impacts on the SAR images, corresponding solutions are proposed.Finally the techniques of MOCO are classified and summarized.(3) Two-dimensional space-variant motion errors are studied comprehensively.Envelope correction, first-order compensation, second-order compensation,narrow beam compensation and wide beam compensation are discussed individually. Three narrow beam MOCO algorithms are deeply studied, includingMOCO integrated in R-DA, in CSA and in RMA. Some innovative research ismade in the wide beam MOCO. Three different wide beam MOCO algorithms areproposed for stripmap SAR, which are block by block compensation in frequencydomain, overlapped block processing and frequency division based MOCO.PF-OSA integrated with MOCO is an algorithm for spotlight SAR. The block byblock compensation achieves computation efficiency and precisioncompromisingly in the case of low-frequency errors. The last three ones adoptcompensation in time domain and can correct two-dimensional space-variant lowand high-frequency motion errors.(4) Auto-focus is an important motion compensation method of MOCO for unknownerrors. It consists of three kinds: sub aperture processing, inverse filtering andcost based approaches. Phase gradient auto-focus and entropy based auto-focus(stage by stage approaching, SSA) are introduced with simulation.(5) Real-time MOCO and imaging based on FPGAs are considered at last. On-boardreal-time imaging processor for space borne SAP, is implemented with Virtex-Ⅱchips from Xilinx Corporation. Test result of a point target is shown. Meanwhile,real-time imaging processor with MOCO for airborne SAR is also designed. Thewhole design is implemented on a single chip Virtex-Ⅳand simulation of a blockof data (128×128) is finished.
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