严重方位模糊下的合成孔径雷达微弱运动目标聚焦与参数估计方法
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摘要
针对现有运动目标聚焦方法存在的对多普勒模糊敏感、信噪比要求高、不能较好地实现无模糊运动参数估计的问题,提出一种严重方位模糊下的合成孔径雷达微弱运动目标聚焦与参数估计方法。首先,构造方位谱压缩函数压缩目标方位谱带宽;其次,应用二阶Keystone变换补偿距离弯曲;随后,通过所构造的距离走动补偿函数与吕氏分布变换(LVD)完成剩余距离徙动和多普勒徙动的补偿,进而实现目标能量聚焦;最后,结合参数粗估计结果,设计一种LVD域的无模糊参数精估计准则。仿真结果表明:该方法不受方位多普勒谱分裂与LVD域多普勒模糊的影响,具有较强的抗噪性,与Radon分数阶傅里叶变换的方法和基于非线性变换的方法相比,信噪比损失分别降低了约2 dB和15 dB。
A method for weak moving target focusing and parameter estimation of synthetic aperture radars is proposed to solve the problems that existing moving target focusing methods are sensitive to Doppler ambiguity, require high signal-to-noise ratio(SNR) and cannot estimate unambiguous parameter. Firstly, an azimuth spectrum compression function is constructed to compress the azimuth spectrum bandwidth of a target. Secondly, the second-order Keystone transform is applied to correct the range curvature. Then, the residual rang migration and Doppler migration are eliminated by a proposed range walk compensation function and the Lv's distribution(LVD), and the moving target energy focus is finally achieved. Meanwhile, a precise estimation criterion of unambiguous parameters in LVD domain is designed by combining rough parameter estimation results. Simulation results show that the proposed method works well in the presence of Doppler spectrum splitting and Doppler ambiguity in LVD domain and has good anti-noise performance. Comparisons with the Radon fractional Fourier transform method and the nonlinear transform-based method show that the proposed method reduces the loss of SNR by 2 dB and 15 dB, respectively.
A method for weak moving target focusing and parameter estimation of synthetic aperture radars is proposed to solve the problems that existing moving target focusing methods are sensitive to Doppler ambiguity, require high signal-to-noise ratio(SNR) and cannot estimate unambiguous parameter. Firstly, an azimuth spectrum compression function is constructed to compress the azimuth spectrum bandwidth of a target. Secondly, the second-order Keystone transform is applied to correct the range curvature. Then, the residual rang migration and Doppler migration are eliminated by a proposed range walk compensation function and the Lv's distribution(LVD), and the moving target energy focus is finally achieved. Meanwhile, a precise estimation criterion of unambiguous parameters in LVD domain is designed by combining rough parameter estimation results. Simulation results show that the proposed method works well in the presence of Doppler spectrum splitting and Doppler ambiguity in LVD domain and has good anti-noise performance. Comparisons with the Radon fractional Fourier transform method and the nonlinear transform-based method show that the proposed method reduces the loss of SNR by 2 dB and 15 dB, respectively.
引文
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[20] 陈展野,周宇,张林让,等.非均匀环境下利用单个数据集的STAP算法 [J].航空学报,2015,36(12):3938-3946.CHEN Zhanye,ZHOU Yu,ZHANG Linrang,et al.Single data set-STAP algorithm in heterogeneous environment [J].Acta Aeronautica et Astronautica Sinica,2015,36(12):3938-3946.
[2] CHEN Z Y,ZHOU Y,ZHANG L R,et al.General range model for multi-channel SAR/GMTI with curvilinear flight trajectory [J].Electronics Letters,2019,55(2):111-112.
[3] 陈士超,武其松,吴玉峰,等.一种大斜视双基地合成孔雷达的频率变标成像算法 [J].西安交通大学学报,2011,45(10):82-87.CHEN Shichao,WU Qisong,WU Yufeng,et al.A frequency scaling algorithm for high squint bistatic synthetic aperture radar [J].Journal of Xi’an Jiaotong University,2011,45(10):82-87.
[4] TANG S Y,LIN C H,ZHOU Y,et al.Processing of long integration time spaceborne SAR data with curved orbit [J].IEEE Transactions on Geoscience and Remote Sensing,2018,56(2):888-903.
[5] 李刚,许稼,彭应宁,等.基于混合积累的SAR微弱运动目标检测 [J].电子学报,2007,35(3):576-579.LI Gang,XU Jia,PENG Yingning,et al.SAR weak moving target detection based on hybrid integration [J].Acta Electronica Sinica,2007,35(3):576-579.
[6] XU H J,YANG Z W,TIAN M,et al.An extended moving target detection approach for high-resolution multichannel SAR-GMTI systems based on enhanced shadow-aided decision [J].IEEE Transactions on Geoscience and Remote Sensing,2018,56(2):715-729.
[7] OVEIS A H,SEBT M A.Coherent method for ground-moving target indication and velocity estimation using Hough transform [J].IET Radar Sonar Navigation,2017,11(4):646-655.
[8] 万俊,周宇,张林让,等.基于时间反转和降阶Keystone的SAR-GMTI快速聚焦方法 [J].航空学报,2018,39(6):321862.WAN Jun,ZHOU Yu,ZHANG Linrang,et al.A fast SAR-GMTI focusing method based on time reversal and reduced-order Keystone [J].Acta Aeronautica et Astronautica Sinica,2018,39(6):321862.
[9] BAI Y C,DAI Z N,ZHANG X G,et al.High accuracy velocity measurement based on Keystone transform using entropy minimization [J].Chinese Journal of Electronics,2016,25(4):774-778.
[10] ZHOU F,WU R,XING M D,et al.Approach for single channel SAR ground moving target imaging and motion parameter estimation [J].IET Radar Sonar Navigation,2007,1(1):59-66.
[11] KIRKLAND D.Imaging moving targets using the second-order Keystone transform [J].IET Radar Sonar Navigation,2011,5(8):902-910.
[12] PERRY R P,DIPIETRO R C,FANTE R.SAR imaging of moving targets [J].IEEE Transactions on Aerospace and Electronic Systems,1999,35(1):188-200.
[13] HUANG P H,LIAO G S,YANG Z W,et al.An approach for refocusing of ground moving target without target motion parameter estimation [J].IEEE Transactions on Geoscience and Remote Sensing,2017,55(1):336-350.
[14] XIN Z H,LIAO G S,YANG Z W,et al.A fast ground moving target focusing method based on first-order discrete polynomial-phase transform [J].Digital Signal Processing,2017,60:287-295.
[15] CHEN X L,GUAN J,LIU N B,et al.Maneuvering target detection via Radon-fractional Fourier transform based long-time coherent integration [J].IEEE Transactions on Signal Processing,2014,62(4):939-953.
[16] Lü X L,BI G A,WAN C R,et al.Lv’s distribution:principle,implementation,properties,and performance [J].IEEE Transactions on Signal Processing,2011,59(8):3576-3591.
[17] LUO S,BI G A,Lü X L,et al.Performance analysis on Lv’s distribution and its applications [J].Digital Signal Processing,2013,23:797-807.
[18] BARBAROSSA S,LORENZO P D,VECCHIARELLI P.Parameter estimation of 2D multi-component polynomial phase signals:an application to SAR imaging of moving targets [J].IEEE Transactions on Signal Processing,2014,62(17):4375-4389.
[19] ZHU S Q,LIAO G S,QU Y,et al.Ground moving targets imaging algorithm for synthetic aperture radar [J].IEEE Transactions on Geoscience and Remote Sensing,2011,49(1):462-477.
[20] 陈展野,周宇,张林让,等.非均匀环境下利用单个数据集的STAP算法 [J].航空学报,2015,36(12):3938-3946.CHEN Zhanye,ZHOU Yu,ZHANG Linrang,et al.Single data set-STAP algorithm in heterogeneous environment [J].Acta Aeronautica et Astronautica Sinica,2015,36(12):3938-3946.