doi:

DOI: 10.3724/SP.J.1300.2012.20035

Journal of Radars (雷达学报) 2012/1:3 PP.309-313

Study of Effects of Flat Surface Assumption to Synthetic Aperture Radar Time-domain Algorithms Imaging Quality


Abstract:
Time-domain algorithms have great application prospect in Ultra Wide Band Synthetic Aperture Radar (UWB SAR) imaging for its advantages such as perfect focusing and perfect motion compensation. We could adopt the flat surface assumption to simplify the imaging geometric model, when undulating terrain is imaged using time-domain algorithms. Nevertheless, the flat surface assumption leads to geometric errors, thereby affecting the imaging results. This paper studies the effects of this assumption on time-domain imaging algorithms, points out that it leads to position offset problem in the case of linear aperture, and it even leads to target defocusing problem in the case of non-linear aperture. The expression of position offset is given in this paper, as well as the restriction of the maximal offset of the non-linear aperture and the maximum elevation of the area in order to focus the targets. The conclusions are validated by simulated data, which is processed by one kind of time-domain algorithms, namely Back Projection (BP) algorithm.

Key words:Flat surface assumption,Undulating terrain,Time-domain algorithms,Back Projection (BP) algorithm

ReleaseDate:2014-07-21 16:24:02



[1] Vu V T, Sjogren T K, and Pettersson M I. On apodization techniques for ultra-wideband SAR imaging[C]. Proceeding of European Radar Conference, Rome, Italy, 2009: 529-532.

[2] McCorkle John W. Focusing of synthetic aperture ultra wideband data[C]. International Geoscience and Remote Sensing (IGRSS), Fairbora, USA, 1991: 1-5.

[3] Yegulalp A F. Fast Backprojection algorithm for synthetic aperture radar[C]. IEEE Radar Conference, Waltham, MA, 1999: 60-65.

[4] Ahmed I. Study of the local backprojection algorithm for image formation in ultra wideband synthetic aperture radar[D]. [Ph.D. dissertation], Sweden: Bleking Institute of Technology, 2008: 31-41.

[5] John McCorkle and Martin Rofheart. An order N2log(N) backprojector algorithm for focusing wide-angle wide- bandwidth arbitrary-motion synthetic aperture radar[C]. International Society for Optical Engineering (SPIE) AeroSense Conference, Orlando: FL, 1996: 25-36.

[6] Seung-Mok Oh and James H McClellan. Multiresolution imaging with quadtree backprojection[C]. 35th Asilomar Conference on Signals Systems & Computers, 2001: 105-109.

[7] Ulander L M H, Hellsten H, and Stenström G. Synthetic-aperture radar processing using fast factorized back-projection[J]. IEEE Transactions on Aerospace and Electronic Systems, 2003, 39(3): 760-776.

[8] Vu V T, Sjogren T K, and Pettersson M I. A comparison between fast factorized backprojection and frequency-domain algorithms in UWB low frequency SAR[C]. Proceeding of IEEE International Geoscience and Remote Sensing Symposium (IGARSS), Boston: MA, 2008: 1293-1296.

[9] Othmar Frey, Erich H Meier, and Daniel R Nüesch. Processing SAR data of rugged terrain by time-domain back-projection[C]. Proceedings of International Society for Optical Engineering (SPIE), Bellingham, Wash, 2005, Vol. 5980: 9-20.

[10] Prats P, Reigber A, and Mallorqui J J. Topography-dependent motion compensation for repeat-pass interferometric SAR systems[J]. IEEE Geoscience and Remote Sensing Letters, 2005, 2(2): 206-210.

[11] Jones C, Hensle S, and Michel T. Topography-dependent motion compensation: application to UAVSAR data[C]. 2009 IEEE Radar Conference, California, USA, May 4-8, 2009: 1-6.

[12] Prats P, Karlus A, Câmara de Macedo, et al. Comparison of topography-and aperture-dependent motion compensation algorithms for airborne SAR[J]. IEEE Geoscience and Remote Sensing Letters, 2007, 4(3): 349-353.

[13] Karlus A, Câmara de Macedo, and Scheiber R. Precise topography-and aperture-dependent motion compensation for airborne SAR[J]. IEEE Geoscience and Remote Sensing Letters, 2005, 2(2): 172-176.

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