Abstract：A two-dimensional extrapolated notch filtering method was developed to suppress sidelobes due to isolated strong scatterers in polarimetric synthetic aperture radar (SAR) images and to maintain the statistical and polarization scattering characteristics. A Chirp-Z transform is used for the AR(1) parameter identification with two-dimensional signal extrapolation based on steady-state Kalman prediction theory. The strong scatterer signals are eliminated by filtering the extrapolated signal with a linear-phase equiripple notch filter. The mainlobes of the strong scatterer signals are recovered in the frequency domain and the image amplitude error is accurately compensated in the filtering process. Unlike both spatially variant apodization (SVA) and adaptive sidelobe suppression (ASS), this method preserves the image resolution, the statistics and the polarization scattering characteristics with a simpler procedure. The effectiveness of this method is demonstrated by simulated and real data.
李增辉, 常雯, 杨健. 基于外推陷波滤波的孤立强散射旁瓣抑制[J]. 清华大学学报（自然科学版）, 2015, 55(5): 503-507.
LI Zenghui, CHANG Wen, YANG Jian. Sidelobe suppression of isolated strong scatterers based on extrapolated notch filtering. Journal of Tsinghua University(Science and Technology), 2015, 55(5): 503-507.
Oliver C, Quegan S. Understanding Synthetic Aperture Radar Images [M]. Raleigh, NC, USA: SciTech Publishing, 2004.
Cumming I G, Wong F H. Digital Signal Processing of Synthetic Aperture Radar Data: Algorithms and Implementation [M]. London, UK: Artech House, 2004.
杨茹良, 李海英, 李世强, 等. 高分辨率微波成像 [M]. 北京: 国防工业出版社, 2013.YANG Ruliang, LI Haiying, LI Shiqiang, et al. High Resolution Microwave Imaging [M]. Beijing: National Defence Industry Press, 2013. (in Chinese)
杨科, 廖桂生, 徐青, 等. 改进的合成孔径雷达旁瓣抑制空间变迹算法 [J]. 电波科学学报, 2012, 27(6): 1158-1165.YANG Ke, LIAO Guisheng, XU Qing, et al. Improve SVA method or SAR sidelobe suppression [J]. Chinese Journal of Radio Science, 2012, 27(6): 1158-1165. (in Chinese)
DeGraaf S R. Sidelobe reduction via adaptive FIR filtering in SAR imagery [J]. IEEE Transactions on Image Processing, 1994, 3(3): 292-301.
Pastina D, Colone F, Lmobardo P. Effect of apodization on SAR image understanding [J]. IEEE Transaction on Geoscience and Remote Sensing, 2007, 45(11): 3533-3551.
Cao S, Zheng Y F, Ewing R L. Wavelet-based waveform for effective sidelobe suppression in radar signal [J]. IEEE Transactions on Aerospace and Electronic Systems, 2014, 50(1): 265-284.
Madisetti V K. The Digial Signal Processing Handbook [M]. 2nd ED. Boca Raton, FL, USA: CRC press, 2010.
Parks T W, McClellan J H. Chebyshev approximation for nonrecursive digital filters with linear phase [J]. IEEE Transaction Circuit Theory, 1972, CT-19 (2): 189-194.
Tseng C C. Design of two-dimensional FIR digital filters by McClellan transform and quadratic programming [J]. IEE Proc Vision, Image and Signal Processing, 2001, 148 (5) : 325-331.
LI Zenghui, XU Bin, YANG Jian, et al. A steady-state Kalman predictor-based filtering strategy for non-overlapping sub-band spectral estimation [J]. Sensors, 2015, 15: 110-134.
邓自立. 最优估计理论及其应用: 建模、滤波、信息融合估计 [M]. 哈尔滨: 哈尔滨工业大学出版社, 2005.DENG Zili. Optimal Estimation Theory with Applications-Modeling, Filtering and Information Fusion Estimation [M]. Harerbin: Harbin Institute of Technology Press, 2005. (in Chinese)