航空学报 > 2014, Vol. 35 Issue (11): 3074-3081   doi: 10.7527/S1000-6893.2014.0168

机载SAR反投影图像自聚焦处理方法

王昕1,3, 朱岱寅2, 蒋锐3   

  1. 1. 毫米波国家重点实验室, 江苏 南京 210096;
    2. 南京航空航天大学 电子信息工程学院, 江苏 南京 210016;
    3. 南京邮电大学 通信与信息工程学院, 江苏 南京 210003
  • 收稿日期:2013-12-24 修回日期:2014-07-27 出版日期:2014-11-25 发布日期:2014-08-15
  • 通讯作者: 王昕,Tel.:025-83492250 E-mail: wangx@njupt.edu.cn E-mail:wangx@njupt.edu.cn
  • 作者简介:王昕 女, 博士, 讲师, 硕士生导师.主要研究方向: 雷达信号处理. Tel: 025-83492250 E-mail: wangx@njupt.edu.cn
  • 基金资助:

    中国博士后科学基金(2014M551630);江苏省博士后科研资助计划(1302089B);江苏省高校自然科学研究项目(14KJ B510024);中央高校基本科研业务费(NJ20140008);南京航空航天大学基本科研业务费(NS2013023); 毫米波国家重点实验室开放课题(K201506)

Autofocus Method of Airborne SAR Imagery Reconstructed via Backprojection

WANG Xin1,3, ZHU Daiyin2, JIANG Rui3   

  1. 1. State key Laboratory of Millimeter Waves, Nanjing 210096, China;
    2. College of Electronic Information Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China;
    3. College of Telecommunications and Information Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210003, China
  • Received:2013-12-24 Revised:2014-07-27 Online:2014-11-25 Published:2014-08-15
  • Supported by:

    China Postdoctoral Science Foundation (2014M551630); Jiangsu Planned Projects for Postdoctoral Research Funds (1302089B); Natural Science Foundation of the Jiangsu Higher Education Institutions of China(14KJB510024); Fundamental Research Funds for the Central Universities (NJ20140008); NUAA Fundamental Research Funds(NS2013023); Open Reasearch Program of State Key Laboratory of Millimeter Waves (K201506)

摘要:

反投影算法(BPA)是一种经典的时间域合成孔径雷达(SAR)成像处理方法.BPA对回波数据插值累加得到图像,运动误差导致的目标散焦沿不同的倾斜角度存在,无法直接应用现有的自聚焦算法.为此,提出了一种新颖的BPA图像运动补偿方案.基于反投影数据运动相位误差和距离徙动分析,研究了修正投影栅格成像,从而去除重建图像中目标散焦方向的空变特性.在中低分辨率配置下,重建SAR图像能够直接应用相位梯度自聚焦(PGA)等进行运动补偿.点目标仿真实验和实测数据结果验证了该算法的有效性.

关键词: 合成孔径雷达, 反投影算法, 相位误差, 运动补偿, 相位梯度自聚焦

Abstract:

Backprojection algorithm (BPA) is a classic time domain synthetic aperture radar(SAR) imaging method. Since the imagery reconstructed via BPA is derived via interpolation and accumulation of SAR phase history data, defocus due to motion error will along variant directions and hence traditional autofocus methods cannot be applied directly. To solve this problem, a novel autofocus method for BPA reconstructed imagery is proposed in this paper. Based on the analysis of motion phase error and range migration of BPA processed data, imaging grid is modified to eliminate the space variance of defocus in imagery. The reconstructed SAR imageries after modification can be motion compensated by the phase gradient autofocus (PGA) algorithm in low and moderate resolution cases. Point target simulation results and real data results validate this algorithm.

Key words: synthetic aperture radar, backprojection algorithm, phase error, motion compensation, phase gradient autofocus

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