Two-Stage Focusing Algorithm for Highly Squinted Synthetic Aperture Radar Imaging

Highly squinted synthetic aperture radar (SAR) data focusing is a challenging problem with difficulty to correct the severe range-azimuth coupling and motion errors. Squint minimization processing with the range-walk correction is widely adapted to simplify the decoupling processing, while it destructs the azimuth-shift invariance of conventional SAR transfer function. In this paper, a two-stage focusing algorithm (TSFA) is proposed to generate a focused imagery for the highly squinted airborne SAR. In the proposed algorithm, conventional range cell migration correction and azimuth matched filtering are performed and a fine focusing stage is established to correct the azimuth variance. In the fine focusing procedure, the coarse-focused image is divided into azimuth blocks to accommodate the correction of azimuth-variant residual range migration and phase terms. Moreover, precise motion compensation is embedded into the TSFA procedure to form an accurate airborne SAR imagery, which may be called the extended TSFA. In order to balance the processing precision and computational load, optimal selection of block size is investigated in detail. Both simulated and real measured airborne SAR data sets are used to validate the proposed approaches.

[1]  Ian G. Cumming,et al.  Signal properties of spaceborne squint-mode SAR , 1997, IEEE Trans. Geosci. Remote. Sens..

[2]  Chibiao Ding,et al.  Precise Focusing of Airborne SAR Data With Wide Apertures Large Trajectory Deviations: A Chirp Modulated Back-Projection Approach , 2015, IEEE Transactions on Geoscience and Remote Sensing.

[3]  Mengdao Xing,et al.  Focus Improvement of Highly Squinted Data Based on Azimuth Nonlinear Scaling , 2011, IEEE Transactions on Geoscience and Remote Sensing.

[4]  Wei Song,et al.  Comparison of two-step and one-step motion compensation algorithms for airborne synthetic aperture radar , 2015 .

[5]  Jordi J. Mallorquí,et al.  Comparison of Topography- and Aperture-Dependent Motion Compensation Algorithms for Airborne SAR , 2007, IEEE Geoscience and Remote Sensing Letters.

[6]  M.R. Ito,et al.  A chirp scaling approach for processing squint mode SAR data , 1996, IEEE Transactions on Aerospace and Electronic Systems.

[7]  Wang Jun,et al.  A New Improved Step Transform Algorithm for Highly Squint SAR Imaging , 2011, IEEE Geoscience and Remote Sensing Letters.

[8]  Mengdao Xing,et al.  Azimuth Overlapped Subaperture Algorithm in Frequency Domain for Highly Squinted Synthetic Aperture Radar , 2013, IEEE Geoscience and Remote Sensing Letters.

[9]  Mengdao Xing,et al.  An Azimuth Frequency Non-Linear Chirp Scaling (FNCS) Algorithm for TOPS SAR Imaging With High Squint Angle , 2014, IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing.

[10]  Gianfranco Fornaro,et al.  Azimuth-to-Frequency Mapping in Airborne SAR Data Corrupted by Uncompensated Motion Errors , 2013, IEEE Geoscience and Remote Sensing Letters.

[11]  Richard Bamler,et al.  A comparison of range-Doppler and wavenumber domain SAR focusing algorithms , 1992, IEEE Trans. Geosci. Remote. Sens..

[12]  F. Rocca,et al.  SAR data focusing using seismic migration techniques , 1991 .

[13]  Alberto Moreira,et al.  Airborne SAR processing of highly squinted data using a chirp scaling approach with integrated motion compensation , 1994, IEEE Trans. Geosci. Remote. Sens..

[14]  Ian G. Cumming,et al.  Interpretations of the omega-K algorithm and comparisons with other algorithms , 2003, IGARSS 2003. 2003 IEEE International Geoscience and Remote Sensing Symposium. Proceedings (IEEE Cat. No.03CH37477).

[15]  Yi Liang,et al.  A Frequency-Domain Imaging Algorithm for Highly Squinted SAR Mounted on Maneuvering Platforms With Nonlinear Trajectory , 2016, IEEE Transactions on Geoscience and Remote Sensing.

[16]  Rolf Scheiber,et al.  Precise topography- and aperture-dependent motion compensation for airborne SAR , 2005, IEEE Geoscience and Remote Sensing Letters.

[17]  Yihui Lu,et al.  Time-varying step-transform algorithm for high squint SAR imaging , 1999, IEEE Trans. Geosci. Remote. Sens..

[18]  Tat Soon Yeo,et al.  New applications of nonlinear chirp scaling in SAR data processing , 2001, IEEE Trans. Geosci. Remote. Sens..

[19]  Daoxiang An,et al.  Extended Nonlinear Chirp Scaling Algorithm for High-Resolution Highly Squint SAR Data Focusing , 2012, IEEE Transactions on Geoscience and Remote Sensing.

[20]  R. Keith Raney,et al.  Precision SAR processing using chirp scaling , 1994, IEEE Trans. Geosci. Remote. Sens..

[21]  Giorgio Franceschetti,et al.  On center-beam approximation in SAR motion compensation , 2006, IEEE Geoscience and Remote Sensing Letters.

[22]  Yihui Lu,et al.  A new subaperture approach to high squint SAR processing , 2001, IEEE Trans. Geosci. Remote. Sens..

[23]  Zheng Bao,et al.  Focus Improvement of High-Squint SAR Based on Azimuth Dependence of Quadratic Range Cell Migration Correction , 2013, IEEE Geoscience and Remote Sensing Letters.

[24]  Mandy Eberhart,et al.  Spotlight Synthetic Aperture Radar Signal Processing Algorithms , 2016 .

[25]  N. Hamano,et al.  Digital processing of synthetic aperture radar data , 1984 .

[26]  Ian G. Cumming,et al.  A Two-Dimensional Spectrum for Bistatic SAR Processing Using Series Reversion , 2007, IEEE Geoscience and Remote Sensing Letters.

[27]  Alberto Moreira,et al.  Extended wavenumber-domain synthetic aperture radar focusing with integrated motion compensation , 2006 .

[28]  Alberto Moreira,et al.  SAR Processing with Motion Compensation using the Extended Wavenumber Algorithm , 2004 .