方素娟¹,
李光祚^1,,,
张益霏²,
郁文贤¹,
吴一戎^{1, 2}
1.上海交通大学电子信息与电气工程学院 上海 200240
2.中国科学院电子学研究所 北京 100190

详细信息

作者简介:方素娟：女，1970年生，研究员，研究方位为合成孔径雷达系统、雷达信号处理
李光祚：男，1985年生，博士生，研究方向为合成孔径雷达与合成孔径激光雷达信号处理
张益霏：男，1983年生，副研究员，研究方向为雷达系统、高分对地观测地面应用
郁文贤：男，1964年生，博士，教授，研究方向为雷达目标识别、遥感信息处理、融合导航定位技术
吴一戎：男，1963年生，博士，研究员，中国科学院院士，研究方向为合成孔径雷达、遥感卫星地面处理与应用系统技术等

通讯作者:李光祚　 hnyzlgz@163.com

中图分类号:TN958

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出版历程

收稿日期:2018-01-19
修回日期:2018-07-24
网络出版日期:2018-08-03
刊出日期:2018-12-01

Method for Frequency Error Compensation Based on Raw Data for SAR System with Bandwidth Synthesis

Sujuan FANG¹,
Guangzuo LI^1,,,
Yifei ZHANG²,
Wenxian YU¹,
Yirong WU^{1, 2}
1. School of Electronic Information and Electrical Engineering, Shanghai Jiaotong University, Shanghai 200240, China
2. Insititute of Electrics, Chinese Academy of Sciences, Beijing 100190, China


摘要
摘要:为了提高SAR系统的分辨率，在距离向可以通过发射一系列不同载频的窄带信号，通过信号处理的方法实现带宽合成，进而得到等效大带宽信号对应的分辨率。为有效实现带宽合成，要求不同子带回波的载频步进值严格已知，这在某些实际应用环境中，并不能总是满足，因而需要从回波数据中直接估计步进值。该文提出一种基于子带回波数据的载频误差估计与补偿方法。该方法基于压缩后子带回波数据多普勒相位与载频的关系，对子带图像进行干涉处理，提取差分相位，并利用差分相位沿方位向的冗余进行相干积累，获得以实际载频步进值为振荡频率的单频信号，进而通过频谱分析方法得到误差频率，并对子带间相位误差进行补偿。通过该方法，能够实现子带信号的相干合成，提升了SAR数据成像质量。实验数据的处理结果验证了该方法的有效性。
关键词:高分宽幅SAR/
带宽合成/
子带频率误差/
相位差分/
相干积累
Abstract:To improve the resolution of the SAR system, radar bandwidth should be improved. By means of synthetic bandwidth, wide bandwidth can be achieved with less hardware complexity. For frequency band synthesis SAR system, frequency difference should be accurately known. However, in the real measurement situation, the frequency difference may drift and should be estimated based on the raw data. In this manuscript, an effective method is proposed to estimate the frequency difference error and compensate the phase error. Based on the relation between the interferometric phase of subband echoes and frequency difference, the frequency difference drift is estimated. The interferometry between subband images yields the interferometric image. It is observed that in the yielded image, phase varies with range and the slope is proportional to the frequency difference. Also, the phase is redundant along azimuth. Based on the redundancy along azimuth, a new vector is formed. The vector is a sinusoidal signal with the frequency value corresponding to the relative range shift. Frequency analysis yields the value of the frequency difference error. Based on the proposed method, the SAR image is improved. The effectiveness of the method is verified by processing the real SAR data.
Key words:High Resolution and Wide Swath SAR (HRWS-SAR)/
Bandwidth synthesis/
Frequency difference drift/
Interferometric phase/
Coherent accumulation



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