Research And Implementation Of Doppler Parameter Estimation For SAR

As the high resolution imaging radar, Synthetic Aperture Radar (SAR) has beenwidely used in military and civil. Doppler parameters are key parameters in the processingof SAR imaging, including the Doppler central frequency and Doppler frequency rate, andhave a great influence on SAR imaging. The error of Doppler central frequency will reducethe image signal-to-noise ratio, increase the azimuth ambiguity, and produce a shift in theposition of image target. Doppler frequency rate has a great effect on the focusing of theimage. With the development of high-resolution SAR, more and more researches focus onthe Doppler frequency estimator.Field Programmable Gate Array (FPGA) uses parallel architecture to realize the digitalsignal processing. It is especially suitable for high-speed signal processing, due to its datathroughput rate. Based on the research of Doppler parameters estimation algorithm, thispaper optimizes the structure of its hardware implementation to reduce the use of logicalresource. As a result of optimization, the whole imaging process (CS Algorithm) can beimplemented on a single FPGA chip. In this paper, the main work includes the followingaspects:1. After comparing various algorithms of Doppler central frequency estimation, choosetime-domain autocorrelation algorithm as the most suitable method to realize on FPGA chip.Optimize the algorithm and the hardware implementation structure, to reduce thecomplexity of the algorithm when realized as a digital circuit, and to save the logicalresource.2. After researching various algorithms of Doppler frequency rate estimation, chooseShift-And-Correlation algorithm as the most suitable method to realize on FPGA chip.Same with the implementation of Doppler central frequency, this paper focuses on theoptimization of the algorithm and the hardware implementation structure, to reduce thecomplexity of the algorithm when realized as a digital circuit, and to save the logicalresource.3. Doppler parameters can be realized by DSP chip and FPGA chip, this paper introduces the difference between these two designs about the effect on SAR real-timeimaging system. From the speed and calculation accuracy, compare the simulation resultsof these two designs. The result proves the necessary of Doppler parameter designed byFPGA chip, and the reliability of the design in this paper.