A back-projection autofocus algorithm based on flight trajectory optimization for synthetic aperture radar imaging

In this paper, a new autofocus algorithm is presented for back-projection (BP) image formation of synthetic aperture radar (SAR) imaging. The approach is based on maximizing a cost function obtained by prominent points in different sub-apertures of constructed SAR image by varying the flight trajectory parameters. While image-quality-based autofocus approach together with BP algorithm can be computationally intensive, we use approximations that allow optimal corrections to be derived. The approach is applicable for focusing different signal processing algorithms by obtaining modified flight trajectory parameters. Different examples demonstrate the effectiveness of the new autofocus approach applied to the frequency modulated continuous wave mode SAR dataset.

[1]  J. D. de Wit,et al.  Development of a high resolution airborne millimeter wave FM-CW SAR , 2004, First European Radar Conference, 2004. EURAD..

[2]  L. P. Ligthart,et al.  First demonstration of an X-band airborne FMCW SAR , 2006 .

[3]  Patrik Dammert,et al.  Autofocus in fast factorized backprojection for processing of SAR images when geometry parameters are unknown , 2010, 2010 IEEE Radar Conference.

[4]  Joshua N. Ash,et al.  An Autofocus Method for Backprojection Imagery in Synthetic Aperture Radar , 2012, IEEE Geoscience and Remote Sensing Letters.

[5]  Leo P. Ligthart,et al.  Signal Processing for FMCW SAR , 2007, IEEE Transactions on Geoscience and Remote Sensing.

[6]  C. D. Gelatt,et al.  Optimization by Simulated Annealing , 1983, Science.

[7]  Riccardo Lanari,et al.  Synthetic Aperture Radar Processing , 1999 .

[8]  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).

[9]  Mateo Burgos-García,et al.  SAR System for UAV Operation with Motion Error Compensation beyond the Resolution Cell , 2008, Sensors.

[10]  Matthew C. Edwards,et al.  Design of a Continuous-Wave Synthetic Aperture Radar System with Analog Dechirp , 2009 .

[11]  Min Liu,et al.  A back-projection fast autofocus algorithm based on minimum entropy for SAR imaging , 2011, 2011 3rd International Asia-Pacific Conference on Synthetic Aperture Radar (APSAR).

[12]  Christophe Magnard,et al.  Focusing of Airborne Synthetic Aperture Radar Data From Highly Nonlinear Flight Tracks , 2009, IEEE Transactions on Geoscience and Remote Sensing.

[13]  Singiresu S. Rao,et al.  Optimization Theory and Applications , 1980, IEEE Transactions on Systems, Man, and Cybernetics.

[14]  M. Edrich.  Design overview and flight test results of the miniaturised SAR sensor MISAR , 2004, First European Radar Conference, 2004. EURAD..

[15]  Milan Horemuž,et al.  Polynomial interpolation of GPS satellite coordinates , 2006 .

[16]  Colin Gilmore,et al.  A comparison of imaging methods using GPR for landmine detection and a preliminary investigation into the SEM for identification of buried objects , 2005 .

[17]  W. Carrara,et al.  Spotlight synthetic aperture radar : signal processing algorithms , 1995 .

[18]  Wen-Qin Wang,et al.  Waveform-Diversity-Based Millimeter-Wave UAV SAR Remote Sensing , 2009, IEEE Trans. Geosci. Remote. Sens..

[19]  David E. Goldberg,et al.  Genetic Algorithms in Search Optimization and Machine Learning , 1988 .

[20]  David G. Long,et al.  microASAR: A Small, Robust LFM-CW SAR for Operation on UAVs and Small Aircraft , 2008, IGARSS 2008 - 2008 IEEE International Geoscience and Remote Sensing Symposium.

[21]  D. E. Goldberg,et al.  Genetic Algorithms in Search, Optimization & Machine Learning , 1989 .

[22]  Ian G. Cumming,et al.  Digital Processing of Synthetic Aperture Radar Data: Algorithms and Implementation , 2005 .

[23]  Charles V. Jakowatz,et al.  Phase gradient autofocus-a robust tool for high resolution SAR phase correction , 1994 .

[24]  M. Schenewerk.  A brief review of basic GPS orbit interpolation strategies , 2003 .

[25]  Russell C. Eberhart,et al.  A discrete binary version of the particle swarm algorithm , 1997, 1997 IEEE International Conference on Systems, Man, and Cybernetics. Computational Cybernetics and Simulation.

[26]  S. Quegan,et al.  Understanding Synthetic Aperture Radar Images , 1998 .

[27]  David G. Long,et al.  Improved processing of the casie SAR data , 2011, 2011 IEEE International Geoscience and Remote Sensing Symposium.