FPGA Implementation of a SAR Two-dimensional Autofocus Approach
Guo Jiang-zhe① Zhu Dai-yin①② Mao Xin-hua①②
①(College of Electronic & Information Engineering, Nanjing University of Aeronautics & Astronautics, Nanjing 210016, China) ②(Radar Imaging & Microwave Photonics Technology Key Laboratory of Ministry of Education, Nanjing University of Aeronautics & Astronautics, Nanjing 210016, China)
For real-time autofocus of defocused images produced by Synthetic Aperture Radar (SAR), the twodimensional autofocus approach proposed in this study is used to correct the residual range cell migration and compensate for the phase error. Next, a block-wise Phase Gradient Autofocus (PGA) is used to correct the space-variant phase error. The Field-Programmable Gate Array (FPGA) design procedures, resource utilization, processing speed, accuracy, and autofocus are discussed in detail. The system is able to autofocus an 8K × 8K complex image with single precision within 5.7 s when the FPGA works at 200 MHz. The processing of the measured data verifies the effectiveness and real-time capability of the proposed method.
保铮, 刑孟道, 王彤. 雷达成像技术[M]. 北京: 电子工业出版社, 2005: 186-220. Bao Zheng, Xing Meng-dao, and Wang Tong. Radar Imaging Technology[M]. Beijing: Publishing House of Electronics Industry, 2005: 186-220.
[2]
Zhou Hui, Zhao Feng-jun, Yu Wei-dong, et al.. SAR imaging of ground moving targets with non-ideal motion error compensation[J]. Journal of Radars, 2015, 4(3): 265-275.
[3]
Wahl D E, Eichel P H, Ghiglia D C, et al.. Phase gradient autofocus-a robust tool for high resolution SAR phase correction[J]. IEEE Transactions on Aerospace and Electronic Systems, 1994, 30(3): 827-835.
[4]
卿吉明, 徐浩煜, 梁兴东, 等. 一种可用于实时成像的改进PGA算法[J]. 雷达学报, 2015, doi: 10.12000/JR15037. Qing Ji-ming, Xu Hao-yu, Liang Xing-dong, et al.. An improved phase gradient autofocus algorithm used in real-time processing[J]. Journal of Radars, 2015, doi: 10.12000/JR15037.
[5]
Warner D W, Ghiglia D C, Fitzgerrel A, et al.. Two-dimensional phase gradient autofocus[C]. Proceedings of SPIE Image Reconstruction from Incomplete Data, 2000, 4123: 162-173.
[6]
Zhu Dai-yin. SAR signal based motion compensation through combining PGA and 2-D map drift[C]. 2009 2nd Asian-Pacific Conference on Synthetic Aperture Radar, 2009: 435-438.
[7]
Kirk J C, Lefevre R, Van Dalen Wetters, et al.. Signal based motion compensation (SBMC)[C]. IEEE Radar Conference, 2000: 463-468.
[8]
毛新华, 朱岱寅, 朱兆达. 一种超高分辨率机载聚束SAR 2维自聚焦算法[J]. 航空学报, 2012, 33(7): 1289-1295. Mao Xin-hua, Zhu Dai-yin, and Zhu Zhao-da. 2-D autofocus algorithm for ultra-high resolution airborne spotlight SAR imaging[J]. Acta Aeronautica et Astronautica Sinica, 2012, 33(7): 1289-1295.
[9]
Sandia National Laboratories. A Publication Featuring What's New in Remote Sensing Technology at Sandia National Laboratories. http://www.sandia.gov/radar/ sar.html, 2004, 7.
[10]
Xie Yi-zhuang and Long Teng. Storage and pretreatment of SAR signal based on FPGA[C]. 9th International Conference on Signal Processing, 2008: 2380-2383.
[11]
熊君君, 王贞松, 等. 星载SAR实时成像处理器的FPGA实现[J]. 电子学报, 2006, 33(6): 1070-1072. Xiong Jun-jun, Wang Zhen-song, et al.. The FPGA design of on board SAR real time imaging processor[J]. Acta Electronica Sinica, 2006, 33(6): 1070-1072.
[12]
周芳, 唐禹, 张佳佳, 等. 机载高分辨聚束式SAR实时成像处理系统的FPGA实现[J]. 电子与信息学报, 2011, 33(5): 1248-1252. Zhou Fang, Tang Yu, Zhang Jia-jia, et al.. Real-time image formation for airborne high resolution spotlight SAR based on FPGA[J]. Journal of Electronics & Information Technology, 2011, 33(5): 1248-1252.
[13]
郑晓双, 禹卫东, 李早社. 机载SAR实时运动补偿和成像的FPGA实现[J]. 数据采集与处理, 2008, 23(5): 614-618. Zheng Xiao-shuang, Yu Wei-dong, and Li Zao-she. Real-time motion compensation and image formation for airborne SAR based on FPGA[J]. Journal of Data Acquisition & Processing, 2008, 23(5): 614-618.
[14]
郝智泉, 王贞松, 刘波. FPGA实时实现PGA算法的研究[J]. 计算机研究与发展, 2008, 45(2): 342-347. Hao Zhi-quan, Wang Zhen-song, and Liu Bo. Research on real-time realizing PGA algorithm in FPGA[J]. Journal of Computer Research and Development, 2008, 45(2): 342-347.
