ISAR成像中微多普勒现象及CLEAN技术研究
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摘要
逆合成孔径雷达(ISAR)是一种新型的二维高分辨成像雷达。目标中存在两种因素影响ISAR成像质量:目标中某种形式的微动部件,微动部分对回波造成复杂的调制形成微多普勒现象;目标中的强散射部件,强散射点的旁瓣会掩盖周围的弱点,并成为虚假目标。本文在转台成像模型的基础上着重研究了ISAR成像中的微多普勒效应的特征、对成像的影响、去除其影响的方法和运用CLEAN技术去除强散射点旁瓣以综合提高成像质量。
本文首先根据转台上微动的运动模型,建立散射点微动模型,在ISAR回波模型的基础上得到微动散射点的回波模型,根据回波模型研究分析ISAR成像中微动的回波特征,并分析了微动对ISAR成像处理的影响,通过了仿真实验验证。
其次,根据微动回波特征与主体回波特征的不同,研究了基于自适应高斯短时分数阶傅里叶变换的微多普勒抑制方法,首先将慢时间域回波信号分解为高斯线性调频信号之和,根据回波特征不同,分离为主体回波和微动回波两部分,主体回波用于成像处理,可以得到清晰的目标图像。针对FrFT遍历搜索计算量大的缺点,分析了两级搜索,提出了基于遗传算法的快速信号分解;仿真和实测数据实验验证了这种方法的有效性。
最后,根据ISAR成像点扩散函数理论,阐述了ISAR成像中旁瓣产生的原因;在此基础上,分别研究了相干CLEAN和序列CLEAN两种去旁瓣的技术,对两种CLEAN技术的性能进行了详细分析比较,序列CLEAN技术能够降低虚警率和增强抗噪性,但序列CLEAN时空复杂度大,提出了基于遗传算法的最佳路径搜索的序列CLEAN技术;仿真和实测数据验证了两种CLEAN技术去旁瓣的效果。
Inverse synthetic aperture radar (ISAR) is one kind of radar with high resolution in both two dimensions. There are two factors in the target interfering its ISAR image. One is micro-Doppler phenomenon, which is induced by the micro-motion structure of the target. This will induce additional modulation to the returns. Micro-Doppler Effect will lead to contaminations to the target’s ISAR image. The other is high sidelobes induced by strong scatters, which will submerge weak scatters and become false targets. Based on turntable imaging model, micro-Doppler signatures in ISAR imaging, influence on the imaging process and suppression of micro-motion interference and CLEAN Technology are studied respectively in this paper.
Firstly, based on the motion model, a point–scatter target with micro-motions is set up. The returns by the micro-motion scatter are deduced, then the signature of those returns and the influence of micro-motions on ISAR imaging is analyzed and simulated respectively.
Secondly, micro-Doppler effect suppression methods are studied based on the difference of micro-Motion and bulk returns. Adaptive Gauss Short-time Fractional Fourier Transform is performed to decompose the short-time returns into a summation of linear frequency modulation signals, which are divided into two parts: bulk returns and micro-motion returns. Finally the bulk returns is compressed to obtain target image. In order to improve the speed of traversal search, two step searching is firstly analyzed and then random searching based on genetic algorithm is present. The validity of both methods is verified by simulation and measured data. Finally, the sidelobes in ISAR imaging are analyzed based on the point spread function. And then coherent CLEAN technology and sequence CLEAN technology are introduced. A detailed comparison is carried out between them. Both of technologies could reduce the sidelobes, and sequence CLEAN can reduce false alarm rate and is robust to noise. Limited by high time-space complexity of sequence CLEAN, optional path searching based on GA is proposed. The validity of both methods is verified by simulation and measured data.
本文首先根据转台上微动的运动模型,建立散射点微动模型,在ISAR回波模型的基础上得到微动散射点的回波模型,根据回波模型研究分析ISAR成像中微动的回波特征,并分析了微动对ISAR成像处理的影响,通过了仿真实验验证。
其次,根据微动回波特征与主体回波特征的不同,研究了基于自适应高斯短时分数阶傅里叶变换的微多普勒抑制方法,首先将慢时间域回波信号分解为高斯线性调频信号之和,根据回波特征不同,分离为主体回波和微动回波两部分,主体回波用于成像处理,可以得到清晰的目标图像。针对FrFT遍历搜索计算量大的缺点,分析了两级搜索,提出了基于遗传算法的快速信号分解;仿真和实测数据实验验证了这种方法的有效性。
最后,根据ISAR成像点扩散函数理论,阐述了ISAR成像中旁瓣产生的原因;在此基础上,分别研究了相干CLEAN和序列CLEAN两种去旁瓣的技术,对两种CLEAN技术的性能进行了详细分析比较,序列CLEAN技术能够降低虚警率和增强抗噪性,但序列CLEAN时空复杂度大,提出了基于遗传算法的最佳路径搜索的序列CLEAN技术;仿真和实测数据验证了两种CLEAN技术去旁瓣的效果。
Inverse synthetic aperture radar (ISAR) is one kind of radar with high resolution in both two dimensions. There are two factors in the target interfering its ISAR image. One is micro-Doppler phenomenon, which is induced by the micro-motion structure of the target. This will induce additional modulation to the returns. Micro-Doppler Effect will lead to contaminations to the target’s ISAR image. The other is high sidelobes induced by strong scatters, which will submerge weak scatters and become false targets. Based on turntable imaging model, micro-Doppler signatures in ISAR imaging, influence on the imaging process and suppression of micro-motion interference and CLEAN Technology are studied respectively in this paper.
Firstly, based on the motion model, a point–scatter target with micro-motions is set up. The returns by the micro-motion scatter are deduced, then the signature of those returns and the influence of micro-motions on ISAR imaging is analyzed and simulated respectively.
Secondly, micro-Doppler effect suppression methods are studied based on the difference of micro-Motion and bulk returns. Adaptive Gauss Short-time Fractional Fourier Transform is performed to decompose the short-time returns into a summation of linear frequency modulation signals, which are divided into two parts: bulk returns and micro-motion returns. Finally the bulk returns is compressed to obtain target image. In order to improve the speed of traversal search, two step searching is firstly analyzed and then random searching based on genetic algorithm is present. The validity of both methods is verified by simulation and measured data. Finally, the sidelobes in ISAR imaging are analyzed based on the point spread function. And then coherent CLEAN technology and sequence CLEAN technology are introduced. A detailed comparison is carried out between them. Both of technologies could reduce the sidelobes, and sequence CLEAN can reduce false alarm rate and is robust to noise. Limited by high time-space complexity of sequence CLEAN, optional path searching based on GA is proposed. The validity of both methods is verified by simulation and measured data.
引文
1 V. C. Chen. Analysis of Radar Micro-Doppler Signature with Time-Frequency Transforms. Proceedings of the 10PthPIEEE Workshop on Statistical Signal and Array Processing, 2000: 463~466
2 V. C. Chen. F. Li, S.-S. Ho, H. Wechsler. Analysis of Micro-Doppler Signatures. IEE Proc.-Radar Sonar Navig, Vol.150, No.4, 2003:201~207
3 V. C. Chen. F. Li, Ho, S.-S, H. Wechsler. Micro-Doppler Effect in Radar: Phenomenon, Model and Simulation Study. IEEE Transactions on Aerospace and Electronic System, Vol. 42, No. 1, 2006: 2~21
4 R. E. Gardner. Report 5656, Naval Research Laboratory. Washington. DC, Aug. 1961
5 G. G. Fliss, D. L. Mensa. Instrumentation for RCS Measurements of Modulation Spectral of Aircraft Blades. Proceedings of the IEEE National Radar Conference, Los Angeles (USA): IEEE AES Society, 1986: 95~98
6 H. Schneider. On the Maximum Entropy Method for Doppler Spectral Analysis of the Radar Echoes from Rotating Objects. IEE International Conference, RADAR-87, 1987:279~291
7 J. Martin, B. Mulgrew. Analysis of the Theoretical Return Signal from Aircraft Blades. The Record of the IEEE International Conference Radar, New York (USA), 1990:569~572
8 R. E. Kleinman, R. B. Mack. Scattering by Linearly Vibrating Objects. IEEE Transaction on Antennas and Propagation, AP-27, 1979: 344~352
9 J. Van Bladel, De Zutter, D. Reflections from Linearly Vibration Objects: Plane Mirror at Normal Incidence. IEEE Transactions on Antennas and Propagation, AP-29, 1981: 629~636
10 De Zutter, D. Reflection from Linear Vibration Objects: Plane Mirror at Oblique Incidence. IEEE Transactions on Antennas and Propagation, Vol. AP-27, No.3 1982: 898~903
11 J. E. Gray. The Doppler Spectrum of Accelerating Objects. IEEE International Radar Conference, Arlington, VA, May 1990: 385 - 390
12 J. E. Gray. The Effect of Non-Uniform Motion on the Doppler Spectrum of Scattered Continuous Wave Waveform. IEE Proceedings on Radar, Sonar and Navigation, Vol. 150, No. 4, 2003: 262~270
13 M. S. Zediker, R. R. Rice, J. H. Hollister. Method for Extending Range andSensitivity of a Fiber Optic Micro-Doppler Ladar System and Apparatus Therefore. U. S. Patent 6847817, Dec. 8, 1998
14 T. Thayaparan, S. Abrol, E. Riseborough, L. Stankovic, D. Lamothe. Analysis of Radar Micro-Doppler Signatures from Experimental Helicopter and Human Data. IET Radar Sonar Navig, Vol. 1, No. 4, 2007: 289~29
15 A. Ghaleb, L. Vignaud, J-M. Nicolas. Fine Micro-Doppler Analysis in ISAR Imaging. Geoscience and Remote Sensing Symposium, IGARSS IEEE International, 2007:574~577
16 L. Stankovic, T. Thayaparan. Separation of Target Rigid Body and Micro-Doppler Effects in ISAR Imaging. IEEE Transaction on Aerospace and Electronic Systems, Vol. 42, No. 4, 2006:1496~1506
17 J. Li, H. Ling. Application of Adaptive Chrplet Representation for ISAR Feature Extraction from Targets with Rotating Parts. IEEE Proceedings on Radar Sonar and Navigation, Vol.150, No. 4, 2003: 284~291
18 Li Bin, Wan Jianwei, Yao Kangze, Wang Yan. ISAR Based on Micro-Doppler Analysis and Chirplet Parameter Separation. Synthetic Aperture Radar, 2007. APSAR 2007. 1st Asian and Pacific Conference, 2007: 379~384
19 Q. Zhang, H. Guan, Y. Q Bai. Separation of micro-Doppler Signal Using Extended Hough Transform. IEEE International Conference, 2006:361~364
20 Xueru Bai, Mengdao Xing, Feng Zhou. Imaging of Micromotion Targets With Rotating Parts Based on Empirical-Mode Decomposition. IEEE Transactions on Geoscience and Remote Sensing, Vol.42, No.11, 2008: 3514~3523
21陈行勇,刘永祥,黎湘,郭桂蓉.微多普勒分析和参数估计.红外与毫米波学报, Vol. 25, No. 5, 2006: 360~363
22陈行勇,刘永祥,黎湘,郭桂蓉.雷达目标微多普勒特征提取.信号处理, Vol. 23, No. 2, 2007: 222~226
23陈行勇,黎湘,姜斌.基于微多普勒特征的空中目标识别.现代雷达, Vol. 28, No. 10, 2006: 30~33
24高红卫,文树梁.微多普勒理论建模与仿真研究.中国电子科学研究院学报, Vol. 3, No. 1, 2008: 34~39
25高红卫,谢良贵,文树梁,匡勇.弹道导弹目标微多普勒特征提取.雷达科学与技术, Vol. 6, No. 2, 2008: 96~101
26孙照强,鲁耀兵,李宝柱.弹道目标进动特性的微多普勒研究与特性分析.航天电子对抗, Vol. 24, No. 1, 2008:7~9
27张琳,盛卫星,马晓峰.基于微多普勒效应的雷达目标识别算法.现代雷达, Vol. 29, No. 12, 2007: 35~39
28 Luo Ying, Chi Long, Zhang Qun, Jin Yaqiu. A Novel Method for Extraction of Micro-Doppler Signal. IEEE International Symposium on Microwave, Antenna, Propagation and EMC Technologies For Wireless Communications, 2007:1458~1462
29罗迎,池龙,张群,郭英.用慢时间域积分法实现雷达目标微多普勒信息的提取.电子与信息学报, Vol. 30, No. 9, 2008:2055~2059
30邱耀辉,刘忠,卢汝为,楼柯. CLEAN算法在天文图像空域重建中的应用.云南天文台台刊, No. 2. 2000: 1~9
31 J. Tsao, B. D. Steinberg. Reduction of sidelobe and speckle artifacts in microwave imaging: The CLEAN technique. IEEE trans. Antennas Propag., Vol. 36, No. 4, 1988: 543~556
32 Ranjan Bose, Avraham Freedman, B. D. Steinberg. Sequence CLEAN: A Modified Deconvolution Technique for Microwave Images of Contiguous Targets. IEEE trans on Aerospace and Electronic Systems, Vol. 38, No. 1, 2002: 89~97
33 I. S. Choi, H. T. Kim. Two-dimensional evolutionary programming-based CLEAN. IEEE trans. on Aerospace and Electronic Systems, Vol. 39, No. 1, 2002: 373~382
34 S.Yiping, L. Pingping. An improved method of ISAR image processing. Processing 35th Midewest Symposium Circuits and Systems, Vol. 2: 983~986
35 W. Yang, C. Jainwen, L. Zhong. Research on radar imaging of maneuvering targets. in Processing of International Radar Conference, 2003: 42~44.
36 Marco Martorella, Nicola. Acito and Fabrizio. Berizzi. Statistical CLEAN Technique for ISAR Imaging. IEEE tans. On Geoscience and Remote Sensing, Vol. 45, No. 11, 2007.
37 J. Li, R. Wu, V. C. Chen. Robust autofocus algorithm for ISAR imaging of moving targets. IEEE trans on Aerospace and Electronic Systems. Vol. 37, 2001: 1056~1069
38皮亦鸣,刘醒凡.逆合成孔径雷达图像的旁瓣清除技术.电讯技术, Vol. 32, No. 6, 1992: 6~8
39保铮,邢孟道,王彤.雷达成像技术.电子工业出版社, 2005:231~237
40庄钊文,刘永祥,黎湘.目标微动特性研究进展.电子学报. Vol. 35, No. 3, 2007: 520~524
41娄永杰. ISAR成像中微多普勒效应研究.哈尔滨工业大学硕士论文. 2009: 27~29
42曹志道,刘永坦,宿富林,许荣庆.实验ISAR外场实验及数据处理.逆合成孔径雷达论文集. 1996. 3:56~64
43尹志平.分数阶Fourier变换在逆合成孔径雷达成像处理中的应用.中国科技大学博士论文,2008:93-95
44 Ozaktas H M, et al. Digital Computation of the Fractional Fourier Transform. IEEE Trans on SP. 1999:1335~1347
45齐林,陶然,周永思.基于分数阶Fourier变换的多分量LFM信号的检测和参数估计.中国科学(E刊), Vol. 33, No. 8, 2003: 749~757
46王小平,曹立明.遗传算法—理论、应用与软件实现.西安交通大学. 2002: 18~50
47葛培明.改进的遗传算法及其在工程优化中的应用.西南交通大学博士论文. 2006: 16~20
48曾喻江.基于遗传算法的卫星星座设计.华中科技大学博士论文. 2007: 26~30
49 Ranjan Bose. Sequence CLEAN Technique Using BGA for Contiguous Radar Target Images with High Sidelobes. IEEE Transactions on Aerospace and Electronic Systems. Vol. 39, No. 1, 2003: 368~374
2 V. C. Chen. F. Li, S.-S. Ho, H. Wechsler. Analysis of Micro-Doppler Signatures. IEE Proc.-Radar Sonar Navig, Vol.150, No.4, 2003:201~207
3 V. C. Chen. F. Li, Ho, S.-S, H. Wechsler. Micro-Doppler Effect in Radar: Phenomenon, Model and Simulation Study. IEEE Transactions on Aerospace and Electronic System, Vol. 42, No. 1, 2006: 2~21
4 R. E. Gardner. Report 5656, Naval Research Laboratory. Washington. DC, Aug. 1961
5 G. G. Fliss, D. L. Mensa. Instrumentation for RCS Measurements of Modulation Spectral of Aircraft Blades. Proceedings of the IEEE National Radar Conference, Los Angeles (USA): IEEE AES Society, 1986: 95~98
6 H. Schneider. On the Maximum Entropy Method for Doppler Spectral Analysis of the Radar Echoes from Rotating Objects. IEE International Conference, RADAR-87, 1987:279~291
7 J. Martin, B. Mulgrew. Analysis of the Theoretical Return Signal from Aircraft Blades. The Record of the IEEE International Conference Radar, New York (USA), 1990:569~572
8 R. E. Kleinman, R. B. Mack. Scattering by Linearly Vibrating Objects. IEEE Transaction on Antennas and Propagation, AP-27, 1979: 344~352
9 J. Van Bladel, De Zutter, D. Reflections from Linearly Vibration Objects: Plane Mirror at Normal Incidence. IEEE Transactions on Antennas and Propagation, AP-29, 1981: 629~636
10 De Zutter, D. Reflection from Linear Vibration Objects: Plane Mirror at Oblique Incidence. IEEE Transactions on Antennas and Propagation, Vol. AP-27, No.3 1982: 898~903
11 J. E. Gray. The Doppler Spectrum of Accelerating Objects. IEEE International Radar Conference, Arlington, VA, May 1990: 385 - 390
12 J. E. Gray. The Effect of Non-Uniform Motion on the Doppler Spectrum of Scattered Continuous Wave Waveform. IEE Proceedings on Radar, Sonar and Navigation, Vol. 150, No. 4, 2003: 262~270
13 M. S. Zediker, R. R. Rice, J. H. Hollister. Method for Extending Range andSensitivity of a Fiber Optic Micro-Doppler Ladar System and Apparatus Therefore. U. S. Patent 6847817, Dec. 8, 1998
14 T. Thayaparan, S. Abrol, E. Riseborough, L. Stankovic, D. Lamothe. Analysis of Radar Micro-Doppler Signatures from Experimental Helicopter and Human Data. IET Radar Sonar Navig, Vol. 1, No. 4, 2007: 289~29
15 A. Ghaleb, L. Vignaud, J-M. Nicolas. Fine Micro-Doppler Analysis in ISAR Imaging. Geoscience and Remote Sensing Symposium, IGARSS IEEE International, 2007:574~577
16 L. Stankovic, T. Thayaparan. Separation of Target Rigid Body and Micro-Doppler Effects in ISAR Imaging. IEEE Transaction on Aerospace and Electronic Systems, Vol. 42, No. 4, 2006:1496~1506
17 J. Li, H. Ling. Application of Adaptive Chrplet Representation for ISAR Feature Extraction from Targets with Rotating Parts. IEEE Proceedings on Radar Sonar and Navigation, Vol.150, No. 4, 2003: 284~291
18 Li Bin, Wan Jianwei, Yao Kangze, Wang Yan. ISAR Based on Micro-Doppler Analysis and Chirplet Parameter Separation. Synthetic Aperture Radar, 2007. APSAR 2007. 1st Asian and Pacific Conference, 2007: 379~384
19 Q. Zhang, H. Guan, Y. Q Bai. Separation of micro-Doppler Signal Using Extended Hough Transform. IEEE International Conference, 2006:361~364
20 Xueru Bai, Mengdao Xing, Feng Zhou. Imaging of Micromotion Targets With Rotating Parts Based on Empirical-Mode Decomposition. IEEE Transactions on Geoscience and Remote Sensing, Vol.42, No.11, 2008: 3514~3523
21陈行勇,刘永祥,黎湘,郭桂蓉.微多普勒分析和参数估计.红外与毫米波学报, Vol. 25, No. 5, 2006: 360~363
22陈行勇,刘永祥,黎湘,郭桂蓉.雷达目标微多普勒特征提取.信号处理, Vol. 23, No. 2, 2007: 222~226
23陈行勇,黎湘,姜斌.基于微多普勒特征的空中目标识别.现代雷达, Vol. 28, No. 10, 2006: 30~33
24高红卫,文树梁.微多普勒理论建模与仿真研究.中国电子科学研究院学报, Vol. 3, No. 1, 2008: 34~39
25高红卫,谢良贵,文树梁,匡勇.弹道导弹目标微多普勒特征提取.雷达科学与技术, Vol. 6, No. 2, 2008: 96~101
26孙照强,鲁耀兵,李宝柱.弹道目标进动特性的微多普勒研究与特性分析.航天电子对抗, Vol. 24, No. 1, 2008:7~9
27张琳,盛卫星,马晓峰.基于微多普勒效应的雷达目标识别算法.现代雷达, Vol. 29, No. 12, 2007: 35~39
28 Luo Ying, Chi Long, Zhang Qun, Jin Yaqiu. A Novel Method for Extraction of Micro-Doppler Signal. IEEE International Symposium on Microwave, Antenna, Propagation and EMC Technologies For Wireless Communications, 2007:1458~1462
29罗迎,池龙,张群,郭英.用慢时间域积分法实现雷达目标微多普勒信息的提取.电子与信息学报, Vol. 30, No. 9, 2008:2055~2059
30邱耀辉,刘忠,卢汝为,楼柯. CLEAN算法在天文图像空域重建中的应用.云南天文台台刊, No. 2. 2000: 1~9
31 J. Tsao, B. D. Steinberg. Reduction of sidelobe and speckle artifacts in microwave imaging: The CLEAN technique. IEEE trans. Antennas Propag., Vol. 36, No. 4, 1988: 543~556
32 Ranjan Bose, Avraham Freedman, B. D. Steinberg. Sequence CLEAN: A Modified Deconvolution Technique for Microwave Images of Contiguous Targets. IEEE trans on Aerospace and Electronic Systems, Vol. 38, No. 1, 2002: 89~97
33 I. S. Choi, H. T. Kim. Two-dimensional evolutionary programming-based CLEAN. IEEE trans. on Aerospace and Electronic Systems, Vol. 39, No. 1, 2002: 373~382
34 S.Yiping, L. Pingping. An improved method of ISAR image processing. Processing 35th Midewest Symposium Circuits and Systems, Vol. 2: 983~986
35 W. Yang, C. Jainwen, L. Zhong. Research on radar imaging of maneuvering targets. in Processing of International Radar Conference, 2003: 42~44.
36 Marco Martorella, Nicola. Acito and Fabrizio. Berizzi. Statistical CLEAN Technique for ISAR Imaging. IEEE tans. On Geoscience and Remote Sensing, Vol. 45, No. 11, 2007.
37 J. Li, R. Wu, V. C. Chen. Robust autofocus algorithm for ISAR imaging of moving targets. IEEE trans on Aerospace and Electronic Systems. Vol. 37, 2001: 1056~1069
38皮亦鸣,刘醒凡.逆合成孔径雷达图像的旁瓣清除技术.电讯技术, Vol. 32, No. 6, 1992: 6~8
39保铮,邢孟道,王彤.雷达成像技术.电子工业出版社, 2005:231~237
40庄钊文,刘永祥,黎湘.目标微动特性研究进展.电子学报. Vol. 35, No. 3, 2007: 520~524
41娄永杰. ISAR成像中微多普勒效应研究.哈尔滨工业大学硕士论文. 2009: 27~29
42曹志道,刘永坦,宿富林,许荣庆.实验ISAR外场实验及数据处理.逆合成孔径雷达论文集. 1996. 3:56~64
43尹志平.分数阶Fourier变换在逆合成孔径雷达成像处理中的应用.中国科技大学博士论文,2008:93-95
44 Ozaktas H M, et al. Digital Computation of the Fractional Fourier Transform. IEEE Trans on SP. 1999:1335~1347
45齐林,陶然,周永思.基于分数阶Fourier变换的多分量LFM信号的检测和参数估计.中国科学(E刊), Vol. 33, No. 8, 2003: 749~757
46王小平,曹立明.遗传算法—理论、应用与软件实现.西安交通大学. 2002: 18~50
47葛培明.改进的遗传算法及其在工程优化中的应用.西南交通大学博士论文. 2006: 16~20
48曾喻江.基于遗传算法的卫星星座设计.华中科技大学博士论文. 2007: 26~30
49 Ranjan Bose. Sequence CLEAN Technique Using BGA for Contiguous Radar Target Images with High Sidelobes. IEEE Transactions on Aerospace and Electronic Systems. Vol. 39, No. 1, 2003: 368~374