星上SAR实时成像处理关键技术研究

发布时间：2017-12-27 10:03

本文关键词：星上SAR实时成像处理关键技术研究　出处：《北京理工大学》2016年博士论文　论文类型：学位论文

【摘要】：随着星载SAR成像技术的不断进步和应用需求的增加,在星上完成SAR实时成像处理已成为一种发展趋势。星载SAR成像算法复杂、处理量大,在星上环境对系统体积、重量、功耗的严格约束下,星上SAR处理系统的实时性难以保证。为了在单片FPGA上实现星载SAR成像所有处理流程,构建星上SAR实时成像处理系统,本文重点研究了星载SAR成像算法的实时性优化、SAR成像处理矩阵转置存储方法以及星载SAR成像算法中的多种超越函数的实现。论文主要工作及创新成果如下:1.对星载SAR成像算法、星上SAR实时成像核心处理器和系统架构进行研究。选择了以FPGA为核心处理器实现CS成像算法作为构建星上SAR实时成像处理系统的技术途径,提出了标准化、模块化、可扩展的星上SAR实时成像处理系统架构。2.针对星载SAR成像算法在FPGA实现中遇到的运算量大、实时性不足等问题,对多普勒参数估计方法进行选择和优化,研究了相位补偿因子对成像精度和实时性的影响,提出了一种补偿因子区域不变的CS成像算法。该方法在保证星载SAR算法成像质量的前提下,能够有效减小补偿因子的计算量,提高SAR成像算法处理效率。3.针对SAR成像处理过程中转置存储器的数据访问效率过低的问题,对SAR成像处理矩阵转置存储方法进行研究,提出了矩阵分块三维映射法和矩阵分块交叉映射法。这两种转置存储方法充分利用了转置存储器的数据访问时序特性,能够有效提高SAR成像处理过程中转置存储器的数据访问效率,提高SAR成像处理实时性。4.针对星载SAR成像算法中多种超越运算的FPGA实现占用资源过大的问题,对实现正余弦、反正切函数的传统CORDIC算法进行了角度覆盖范围、硬件资源、运算精度等方面的优化和改进,同时对实现反正余弦函数的双迭代结构的CORDIC算法进行了改进,解决了原算法计算结果超出反正余弦函数值域的问题,进而实现了一种多模式CORDIC算法,能够实现正余弦函数和反正余弦函数运算的实时切换,在正余弦、反正余弦函数都需要的算法实现中能够有效减少硬件资源占用。5.本文最后结合各章节研究内容,在单片FPGA上实现了星载SAR成像算法所有处理流程,进而构建了星上SAR实时成像处理系统原理样机,为实现星上SAR实时成像处理奠定了技术基础。
[Abstract]:With the continuous progress of satellite borne SAR imaging technology and the increase of application demand, it has become a development trend to complete SAR real-time imaging processing on the star. The spaceborne SAR imaging algorithm is complex and has a large amount of processing. Under the strict constraint of the volume, weight and power consumption of the satellite environment, the real-time performance of the SAR processing system on the satellite is difficult to guarantee. In order to realize on a single FPGA for Spaceborne SAR imaging of all processes, construction of spaceborne SAR real-time image processing system, this paper focuses on the realization of a variety of spaceborne SAR imaging algorithm, the real-time optimization of SAR imaging matrix transpose storage method and spaceborne SAR imaging algorithm of transcendental function. The main work and innovative results of this paper are as follows: 1. the research on the satellite borne SAR imaging algorithm, the core SAR real-time imaging core processor and the system architecture are carried out. The CS imaging algorithm based on FPGA as the core processor is chosen as the technical way to build real-time SAR imaging processing system. A standardized, modular and scalable SAR real-time imaging processing system architecture is proposed. Computation of 2. for Spaceborne SAR imaging algorithms encountered in the implementation of FPGA, the problem of real-time, the estimation of Doppler parameters selection and optimization method, studied the effect of phase compensation factor to the imaging accuracy and real-time, proposes a compensation factor invariant CS imaging algorithm. This method can effectively reduce the computation of compensation factor and improve the processing efficiency of SAR imaging algorithm on the premise of guaranteeing the imaging quality of the spaceborne SAR algorithm. 3., in view of the low efficiency of data access in transposed memory in the process of SAR image processing, we studied the matrix transposition storage method of SAR imaging processing, and proposed the matrix block three dimensional mapping method and the matrix block cross mapping method. The two transposition storage methods make full use of the data access timing characteristics of the transposed memory, which can effectively improve the data access efficiency of the transposed memory in the process of SAR imaging, and improve the real-time performance of SAR imaging. 4. for a variety of operations beyond the spaceborne FPGA SAR imaging algorithm to achieve resource is too large, the traditional CORDIC algorithm to realize the sine cosine and arctangent function is optimized and improved angle of coverage, hardware resources, operation accuracy, and implementation of the CORDIC double iterative algorithm of structure of sine and cosine functions the improved algorithm solves the original results beyond the range anyway cosine function, and implements a multi mode CORDIC algorithm can realize sine cosine function and cosine function anyway real-time switch operation, in the realization of sine and cosine, anyway, cosine function needs algorithm to reduce the hardware resource occupied. 5., finally, combined with the research contents of each chapter, we implemented all processing flow of spaceborne SAR imaging algorithm on single chip FPGA, and constructed the prototype of SAR real-time imaging processing system, which laid the technical foundation for real-time SAR imaging processing.
【学位授予单位】：北京理工大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN957.52

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