FMCW体制毫米波SAR实时信号处理方法研究  

Real-Time Signal Processing Methods for Millimeter Wave FMCW SAR

作　　者：冯利鹏 王辉 郑世超 曾朝阳 陈翔 FENG Lipeng;WANG Hui;ZHENG Shichao;ZENG Zhaoyang;CHEN Xiang(Shanghai Key Laboratory of Remote Sensing and Millimeter Wave Information Acquisition and Application Technology,Shanghai Institute of Satellite Engineering,Shanghai 201109,China;Key Laboratory of Millimeter Imaging,Shanghai Academy of Spaceflight Technology,Shanghai 201109,China)

机构地区：[1]上海卫星工程研究所上海市毫米波空天信息获取及应用技术重点实验室,上海201109 [2]上海航天技术研究院毫米波成像技术重点实验室,上海201109

出　　处：《上海航天（中英文）》2022年第3期116-121,共6页Aerospace Shanghai（Chinese&English）

摘　　要：与脉冲体制合成孔径雷达(SAR)相比,调频连续波(FMCW)体制SAR具有体积小、重量轻、分辨率高、功耗低和低截获等一系列优点,目前小型或微小型SAR普遍采用FMCW工作体制。FMCW SAR在整个脉冲重复周期内都发射信号,其信号占空比达到了100%,为了减小数字接收机采样带宽,降低数据率,FMCW体制毫米波SAR一般采取解线频调接收的方式,但其数据量依然很大,而且机载平台受到气流的影响,运动误差很大,需要迭代估计与补偿,给实时处理模块带来了很大压力。为了提高整个机载FMCW SAR系统的信号实时处理性能,需要在算法层面进行改进。提出了一种两次子孔径误差估计和全孔径误差拼接补偿的FMCW SAR实时成像算法,使用相位梯度自聚焦(PGA)算法和图像偏置(MD)算法级联提取子孔径误差;然后进行子孔径误差拼接成全孔径误差补偿原数据,两维脉冲压缩后完成图像聚焦,提高了FMCW体制毫米波SAR成像算法的效率;最后使用机载Ka波段FMCW SAR实测数据,验证了该算法的有效性。Compared with pulse synthetic aperture radar(SAR), frequency modulated continuous wave(FMCW) SAR has a series of advantages,such as small volume,light weight,high resolution,low power consumption,and low interception. At present,FMCW system has been widely used in small or micro SAR. FMCW SAR transmits signals in the whole pulse repetition period(PRT),and its signal duty ratio reaches 100%. In order to reduce the sampling bandwidth of digital receiver and reduce the data rate,FMCW SAR generally adopts the method of dechirp reception. However,the data amount is still large. Moreover,since the airborne platform is affected by air flow and the motion error is large,iterative estimation and compensation are needed,which brings a great challenge to the real-time processing module. In order to improve the real-time performance of the whole FMCW SAR system,the algorithm should be modified. In this paper,an FMCW SAR real-time imaging algorithm with twice subaperture error estimation and full aperture error stitching compensation is proposed. The phase gradient autofocus algorithm(PGA)and map drift algorithm(MD)are used to extract the subaperture error in cascade. Then,the subaperture error is spliced into full aperture error compensation to complete the image focusing,which improves the efficiency of the FMCW millimeter wave SAR imaging algorithm. Finally,the effectiveness of the proposed algorithm is verified by the measured data of airborne Ka band FMCW SAR.

关 键 词：调频连续波 解线频调接收 运动误差 子孔径 相位自聚焦算法 图像偏置算法 

分 类 号：TN911.73[电子电信—通信与信息系统] TP391.9[电子电信—信息与通信工程]