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ACTA AERONAUTICAET ASTRONAUTICA SINICA ›› 2014, Vol. 35 ›› Issue (11): 3074-3081.doi: 10.7527/S1000-6893.2014.0168

• Electronics and Control • Previous Articles     Next Articles

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)

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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