大斜视机载SAR多核DSP实时成像处理架构  

Highly Squinted Airborne SAR Real-time Imaging Processing Architecture Based on Multi-core DSP

作　　者：孟星伟 董兰 朱岱寅 MENG Xingwei;DONG Lan;ZHU Daiyin(Key Laboratory of Radar Imaging and Microwave Photonics,Ministry of Education,Nanjing 211106,China;College of Electronic and Information Engineering,Nanjing University of Aeronautics and Astronautics,Nanjing 211106,China)

机构地区：[1]雷达成像与微波光子教育部重点实验室,南京211106 [2]南京航空航天大学电子信息工程学院,南京211106

出　　处：《现代雷达》2021年第12期7-14,共8页Modern Radar

基　　金：国家重点研发计划基金资助项目(2017YFB0502700);国家自然科学基金资助项目(61671240);航空科学基金资助项目(20182052013)。

摘　　要：大斜视机载合成孔径雷达(SAR)具有很高的灵活性,能够在载机飞临目标区域前对目标进行提前、多次成像。然而,大斜视SAR的高精度成像算法通常较为复杂且计算量大,无法满足实时性需求。据此,文中提出了以极坐标格式算法为核心的多核数字信号处理器(DSP)实时成像处理架构。首先,将SAR回波数据进行两次平滑滤波并按比例方位抽取;然后,在基于尺度变换原理的距离向处理中融入距离单元徙动粗校正操作,以获取最大时域截取点数和降低后续处理的运算量,并与方位高精度Sinc插值级联实现回波信号数据域重采样;最后,采用自聚焦技术进一步补偿方位相位误差来获取高质量聚焦SAR图像。大斜视机载SAR实测结果表明,所提多核DSP处理架构可在0.873 s内完成方位与距离向10 K×4 K像素点数的数据处理,最终输出2 K×2 K图像并能够满足实时成像需求。Highly squinted airborne synthetic aperture radar(SAR)with a considerable flexibility has capability of target imaging in advance and repeatedly.Nevertheless,high-precision imaging algorithms for high squint SAR are generally complicated and have a great computational load that cannot meet the requirement on real time.In this paper,a real-time imaging processing architecture based on multi-core digital signal processor(DSP)is proposed,which is built on the polar format algorithm.First,two-cascade smooth filtering and azimuth down-sample operations are employed for processing the SAR echo data.Then,the principle of chirp scaling is exploited to the range resampling,into which coarse correction method of range cell migration is incorporated.As a consequence,the maximum number of time-domain intercept points and the reduction of computational load in subsequent processing are accomplished,which will be cascaded with high-precision sinc-based interpolation to realize the azimuth resampling.Finally,autofocus technique is employed for further compensating the azimuth phase error so as to obtain the highly focused SAR imagery.Experimental results using the measured high squint airborne SAR data indicate that the proposed DSP processing architecture is capable of processing the 10 K×4 K pixel points in azimuth and range within 0.873 s to generate 2 K×2 K imagery,and hence it can satisfy the requirement of real-time imaging design.

关 键 词：合成孔径雷达 极坐标格式算法 多核数字信号处理器 实时处理 

分 类 号：TN957.52[电子电信—信号与信息处理]