方位向变速扫描星载TOPS SAR信号处理方法  

Signal Processing Method for Spaceborne TOPS SAR with Azimuth-Varying Speed Scanning

作　　者：陈阳阳 徐伟 黄平平[1,2] 谭维贤 CHEN Yangyang;XU Wei;HUANG Pingping;TAN Weixian(College of Information Engineering,Inner Mongolia University of Technology,Hohhot,Inner Mongolia 010051,China;Inner Mongolia Key Laboratory of Radar Technology and Application,Hohhot,Inner Mongolia 010051,China)

机构地区：[1]内蒙古工业大学信息工程学院,内蒙古呼和浩特010051 [2]内蒙古自治区雷达技术与应用重点实验室,内蒙古呼和浩特010051

出　　处：《信号处理》2025年第3期426-436,共11页Journal of Signal Processing

基　　金：国家自然科学基金(62071258,U22A2010)。

摘　　要：循序扫描地形观测模式(Terrain Observation by Progressive Scans,TOPS)是星载合成孔径雷达(Synthetic Aperture Radar,SAR)的一种工作模式,具有宽测绘带的特点。因为星载TOPS SAR的这一特点,该模式被广泛应用于军事和民用领域。在宽测绘带的条件下,TOPS SAR扫描场景内目标的类型会相对变多,目标的方位向分辨率需求也随着目标类型的增多而增多,但一般的TOPS SAR的方位向分辨率单一,不能满足大扫描区域内多种不同类型目标的方位向分辨率需求。方位向变速扫描星载TOPS SAR通过调整SAR天线波束的扫描速率对观测区域进行变速扫描,让不同方位位置的目标拥有不同的扫描时间,从而获得关于不同方位位置目标的不同信息量。因此方位向变速扫描星载TOPS SAR可以实现在同一扫描区域内获得多个方位向分辨率,从而同时满足多个不同类型目标的方位向分辨率需求。但对于方位向变速扫描的星载TOPS SAR信号,一般的信号处理方法不再适用。针对这一问题,本文结合方位向变速扫描星载TOPS SAR信号特点,提出了一种适用于方位向变速扫描TOPS SAR的信号处理方法。其中第一步,利用多普勒中心移除处理和方位向补零处理来尽量消除信号的多普勒混叠现象;第二步,通过去斜、升采样等处理让信号的方位向多普勒总带宽小于SAR系统的脉冲重复频率(Pulse Repetition Frequency,PRF),从而完全消除了信号的多普勒混叠现象;第三步,通过乘以原始多普勒历程恢复函数来恢复信号在没有处理前的多普勒历程,接着进行距离徙动矫正和距离向压缩;最后,采用瞬时信号相移函数和尺度傅里叶变换(Scaled Fourier Transform,SCFT)消除波束旋转中心到卫星的距离变化对方位向距离采样间隔的影响并进行方位向压缩得到SAR图像。通过点目标仿真实验和场景分布目标模拟实验,并对比目标的成像性能指标验证了目标成像结果�Terrain observation by progressive scans(TOPS)is a working mode of spaceborne SAR that has a wide swath.Because of this characteristic,spaceborne TOPS SAR finds wide application in the military and civilian fields.Under wide swath conditions,there tends to be a relatively wide range of target types within the TOPS SAR scanning scene.The azimuth resolution requirements of the targets increase with the increase in the number of target types.However,the azimuth resolution of conventional TOPS SAR is single,which does not accommodate the varying resolution requirements of different target types over a wide scanning range.Spaceborne TOPS SAR with azimuth-varying speed scanning addresses this limitation by adjusting the scanning rate of the SAR antenna beam.This adjustment allows targets at different azimuth positions to be scanned for varying durations,enabling the acquisition of the appropriate information about the targets on the basis of their azimuth positions.Consequently,spaceborne TOPS SAR with azimuth-varying speed scanning can achieve multiple azimuth resolutions within the same scanning area to meet the azimuth resolution requirements of a diverse array of target types simultaneously.However,the conventional signal processing method is no longer adequate for spaceborne TOPS SAR with azimuth-varying speed scanning.Therefore,this study proposes a novel signal processing method that is suitable for spaceborne TOPS SAR with azimuth-varying speed scanning,based on its signal characteristics.Initially Doppler centroid removal processing and azimuth zero padding processing to eliminate the Doppler aliasing phenomenon as much as possible.In the second step,the total azimuth Doppler bandwidth of the signal is made less than the pulse repetition frequency(PRF)of the SAR system via deramping processing,upsampling processing,and other forms of processing.Thus,the Doppler aliasing phenomenon of the signal is completely eliminated.In the third step,the Doppler history of the signal prior to processing is reconstructed by

关 键 词：循序扫描地形观测模式 方位向分辨率 变速扫描 多普勒带宽 

分 类 号：TN958[电子电信—信号与信息处理]