高分辨率机载SAR信号处理研究
|
摘要
综合孔径雷达（SAR）是自五十年代发展起来的一种新型对地观测手段，
获取高分辨率和超高分辨率机载SAR图像是当今SAR发展的重要方向之一。
本文主要了研究SAR信号处理中的两部分内容：成像算法和自聚焦算法。并
把它们应用于处理实际数据，得到了正确结果。
首先引言从多个角度解释SAR的基本概念，介绍SAR的特点和应用。
论文第二章从脉冲压缩和合成孔径天线角度对SAR的基本原理进行分
析。第三章在基本原理的基础上给出成像算法的具体实现步骤，结合中科院电
子所的L-SAR数据，计算了合成孔径雷达的距离向分辨率和方位向分辨率。
经成像处理后得出雷达图像。
理想情况下，SAR回波多普勒信号是线性调频信号，采用合成孔径原理提
高方位向成像分辨率。然而，在实际系统中，回波信号总存在着不受欢迎的相
位误差。本文详细分析了相位误差对机载SAR图像的影响，这些相位误差在
成像处理中将以各种形式降低图像的质量，如几何畸变、分辨率降低、对比度
下降、出现虚假目标以及信噪比降低等。
获取高分辨率SAR图像的关键是包括自聚焦算法在内的运动补偿，自聚
焦技术通过补偿回波信号中的相位误差来获得高的聚焦精度。本文讨论了三种
自聚焦算法，并详细介绍了各自聚焦算法的具体实现步骤。
将自聚焦算法用于处理实际数据改善了图像质量，验证了他们的有效性。
Yuehua Liu (Major: Communications and Information System)
Directed by Professor Linjiao iing
Synthetic aperture radar (SAR) has been a new means for the observation of the earth’s surface since 1950’s. Currently, to obtain high resolution airborne SAR image is one of the most important directions of SAR. The research work of this thesis mainly focuses on two aspects, one is imaging algorithm, the other is autofocus algorithms. Use them to process real data, We get right results.
The introduction firstly explains the essentials of SAR in a variety of aspects. and also discusses its characteristics and application.
Chapter 2 treats the basic principle of SAR from views of pulse compression and synthetic array. Chapter 3 details the realization of imaging algorithm, for the real data recorded by Institute of Electronics, Chinese Academy of Sci ences(IECAS). I calculate its range resolution and azimuth resolution. After being dealt by imaging algorithm, radar images are obtained.
In ideal circumstances, the back scattered echo signal of SAR is chirp signal. With synthetic aperture theory, high azimuth resolution imaging to distant targets can be attained. However, in fact, undesirable phase errors exist. This paper analyzes the effect phase errors on the radar image in detail, such phase errors in a SAR si~na1 history degrade image quality in several ways, such as geometric distortion, loss of resolution, decrease in image contrast, spurious targets, and a reduction in signal-tonoise ratio.
To obtain high resolution SAR image, the key technique is motion compensation, which includes autofocus algorithm. Autofocus algorithm improve image quality by removing a large part of all kinds of phase errors in SAR echo signal. In this paper, I describe three autofocus algorithms, details the realization of those autofocus algorithms.
After applying autofocus algorithms to real radar data, results show that these algorithms are very efficient.
获取高分辨率和超高分辨率机载SAR图像是当今SAR发展的重要方向之一。
本文主要了研究SAR信号处理中的两部分内容：成像算法和自聚焦算法。并
把它们应用于处理实际数据，得到了正确结果。
首先引言从多个角度解释SAR的基本概念，介绍SAR的特点和应用。
论文第二章从脉冲压缩和合成孔径天线角度对SAR的基本原理进行分
析。第三章在基本原理的基础上给出成像算法的具体实现步骤，结合中科院电
子所的L-SAR数据，计算了合成孔径雷达的距离向分辨率和方位向分辨率。
经成像处理后得出雷达图像。
理想情况下，SAR回波多普勒信号是线性调频信号，采用合成孔径原理提
高方位向成像分辨率。然而，在实际系统中，回波信号总存在着不受欢迎的相
位误差。本文详细分析了相位误差对机载SAR图像的影响，这些相位误差在
成像处理中将以各种形式降低图像的质量，如几何畸变、分辨率降低、对比度
下降、出现虚假目标以及信噪比降低等。
获取高分辨率SAR图像的关键是包括自聚焦算法在内的运动补偿，自聚
焦技术通过补偿回波信号中的相位误差来获得高的聚焦精度。本文讨论了三种
自聚焦算法，并详细介绍了各自聚焦算法的具体实现步骤。
将自聚焦算法用于处理实际数据改善了图像质量，验证了他们的有效性。
Yuehua Liu (Major: Communications and Information System)
Directed by Professor Linjiao iing
Synthetic aperture radar (SAR) has been a new means for the observation of the earth’s surface since 1950’s. Currently, to obtain high resolution airborne SAR image is one of the most important directions of SAR. The research work of this thesis mainly focuses on two aspects, one is imaging algorithm, the other is autofocus algorithms. Use them to process real data, We get right results.
The introduction firstly explains the essentials of SAR in a variety of aspects. and also discusses its characteristics and application.
Chapter 2 treats the basic principle of SAR from views of pulse compression and synthetic array. Chapter 3 details the realization of imaging algorithm, for the real data recorded by Institute of Electronics, Chinese Academy of Sci ences(IECAS). I calculate its range resolution and azimuth resolution. After being dealt by imaging algorithm, radar images are obtained.
In ideal circumstances, the back scattered echo signal of SAR is chirp signal. With synthetic aperture theory, high azimuth resolution imaging to distant targets can be attained. However, in fact, undesirable phase errors exist. This paper analyzes the effect phase errors on the radar image in detail, such phase errors in a SAR si~na1 history degrade image quality in several ways, such as geometric distortion, loss of resolution, decrease in image contrast, spurious targets, and a reduction in signal-tonoise ratio.
To obtain high resolution SAR image, the key technique is motion compensation, which includes autofocus algorithm. Autofocus algorithm improve image quality by removing a large part of all kinds of phase errors in SAR echo signal. In this paper, I describe three autofocus algorithms, details the realization of those autofocus algorithms.
After applying autofocus algorithms to real radar data, results show that these algorithms are very efficient.
引文
[1] Brown W．M，Porcello L．J“An Introduction to Synthetic Aperture Radar”， IEEE Spectrum，Sept 1969：52-62．
[2] 杨士中， “合成孔径雷达”，国防工业出版社，1981．
[3] 禹卫东， “合成孔径雷达信号处理”，博士学位论文，1997． 5
[4] 徐德宝，“机载合成孔径雷达运动补偿研究”，硕士学位论文，1999． 6
[5] Carl Wiley，“Synthetic Aperture Radars”，IEEE Trans．AES．，Vol．21，No．3， May 1985．
[6] Brown W．M． Synthetic Aperture Radar．IEEE Trans．On AES，May． 1967：217-229
[7] Wiley C．A，“Synthetic Aperture Radars”，IEEE Trans．On AES，May． 1985：440-443．
[8] J．C．Curlander，R．N．McDonough，“Synthetic Aperture Radar：System and Signal Processing”，John Wiley & Sons，INC．
[9] J．C．Kirk，“Digital Synthetic Aperture Radar Technology”，IEEE international Radar Conference，1975
[10] 中国电子学会， “微波遥感学术会议论文集”，1988
[11] 张澄波， “综合孔径雷达原理、系统分析与应用”，科学出版社， 1989
[12] Donald R．Wehner，“High Resolution Radar'’，Artech House
[13] 王世一， “数字信号处理”，北京理工大学出版社，1987
[14] 沈凤麟，钱玉美， “信号统计分析基础”，中国科学技术大学出版 社， 1989
[15] Mehrdad Soumekh，“Synthetic Aperture Radar Signal Processing with MATLAB Algorithms”，John Wiley & Sons，INC．
[16] D．A．Ausherman，etc．“Development in Radar Imaging”，IEEE Trans．AES．， Vol．20，No．4，July，1984．
[17] 黄永红，毛士艺， “星载合成孔径雷达(SAR)成像处理快速近似算 法”，电子科学学刊，Vol．15，No．6，Nov．1993．
[18] 李立伟， “高分辨率机载合成孔径雷达中运动补偿问题的研究”，博士 学位论文，1998． 10
[19] John C．KIRK，JR．，Motion Compensation For Synthetic Aperture Radar，IEEE Trans．On Aerospace and Electronic systems．Vol．AES-11． No．3． May 1975
[20] P．H．Eichel，D．C．Ghiglia，and C．V．Jakowatz，Jr．，“Speckle processing method for synthetic-aperture-radar phase”，Optics Letters，Vol．14，No．1． January，1． 1989
[21] D．BLACKNELL，“SAR motion compensation using autofocus”．REMOTE SENSING，1991，Vol．12 NO．2，253-275．
[22] Li Xi，Liu Guosui，Jinlin Ni，Autofocus of ISAR Images Based on Entropy Minimization, IEEE Trans．On Aerospace and Electronic systems．Vol．35． No．4，October 1999
[23] Jorgen Dall，A New Frequency Domain Autofocus Algorithm for SAR，IEEE 1991
[24] W．G．Carrara，”Spotlight Synthetic Aperture Radar， Signal Processing Algorithm”，Artech House，1995
[25] Subaperture Autofocus for Synthetic Aperture Radar，IEEE Trans．On Aerospace and Electronic systems，Vol．30，No．2，April 4，1994
[26] J．R．Fienup，Synthetic-aperture radar autofocus by maximizing sharpness， Optics Letters，Vol，25，No．4，February 15，2000
[27] F．Berizzi and G．Corsini，Autofocusing of Inverse Synthetic Aperture Radar Images Using Contrast Optimization，IEEE Trans. Aerospace Electron， 1185-1191． 1996
[28] D.Blacknell, A.P. Blake, C.J. Oliver and R.G. White, A Comparison of BAR Multilook Registration and Contrast Optimization Autofocus Algorithms Applied to Real SAR Data, Radar'92 Conference(IEE Publication 365) , Oct.12,1992,363-366
[29] P.H.Eichel, and C.V.Jakowatz, Phase-gradient algorithm as optimal estimator of phase drivative, Optics Letters, Vol.14, No.1, Oct. 15, 1989
[30] D.E.Wahl, P.H. Eichel, D.C.Ghiglia, and C.V.Jakowatz, Phase Gradient Autofocus-A Robust Tool for High Resolution SAR Phase Correction, IEEE Trans. On Aerospace and Electronic systems, Vol.30, No.3, July 1994
[2] 杨士中， “合成孔径雷达”，国防工业出版社，1981．
[3] 禹卫东， “合成孔径雷达信号处理”，博士学位论文，1997． 5
[4] 徐德宝，“机载合成孔径雷达运动补偿研究”，硕士学位论文，1999． 6
[5] Carl Wiley，“Synthetic Aperture Radars”，IEEE Trans．AES．，Vol．21，No．3， May 1985．
[6] Brown W．M． Synthetic Aperture Radar．IEEE Trans．On AES，May． 1967：217-229
[7] Wiley C．A，“Synthetic Aperture Radars”，IEEE Trans．On AES，May． 1985：440-443．
[8] J．C．Curlander，R．N．McDonough，“Synthetic Aperture Radar：System and Signal Processing”，John Wiley & Sons，INC．
[9] J．C．Kirk，“Digital Synthetic Aperture Radar Technology”，IEEE international Radar Conference，1975
[10] 中国电子学会， “微波遥感学术会议论文集”，1988
[11] 张澄波， “综合孔径雷达原理、系统分析与应用”，科学出版社， 1989
[12] Donald R．Wehner，“High Resolution Radar'’，Artech House
[13] 王世一， “数字信号处理”，北京理工大学出版社，1987
[14] 沈凤麟，钱玉美， “信号统计分析基础”，中国科学技术大学出版 社， 1989
[15] Mehrdad Soumekh，“Synthetic Aperture Radar Signal Processing with MATLAB Algorithms”，John Wiley & Sons，INC．
[16] D．A．Ausherman，etc．“Development in Radar Imaging”，IEEE Trans．AES．， Vol．20，No．4，July，1984．
[17] 黄永红，毛士艺， “星载合成孔径雷达(SAR)成像处理快速近似算 法”，电子科学学刊，Vol．15，No．6，Nov．1993．
[18] 李立伟， “高分辨率机载合成孔径雷达中运动补偿问题的研究”，博士 学位论文，1998． 10
[19] John C．KIRK，JR．，Motion Compensation For Synthetic Aperture Radar，IEEE Trans．On Aerospace and Electronic systems．Vol．AES-11． No．3． May 1975
[20] P．H．Eichel，D．C．Ghiglia，and C．V．Jakowatz，Jr．，“Speckle processing method for synthetic-aperture-radar phase”，Optics Letters，Vol．14，No．1． January，1． 1989
[21] D．BLACKNELL，“SAR motion compensation using autofocus”．REMOTE SENSING，1991，Vol．12 NO．2，253-275．
[22] Li Xi，Liu Guosui，Jinlin Ni，Autofocus of ISAR Images Based on Entropy Minimization, IEEE Trans．On Aerospace and Electronic systems．Vol．35． No．4，October 1999
[23] Jorgen Dall，A New Frequency Domain Autofocus Algorithm for SAR，IEEE 1991
[24] W．G．Carrara，”Spotlight Synthetic Aperture Radar， Signal Processing Algorithm”，Artech House，1995
[25] Subaperture Autofocus for Synthetic Aperture Radar，IEEE Trans．On Aerospace and Electronic systems，Vol．30，No．2，April 4，1994
[26] J．R．Fienup，Synthetic-aperture radar autofocus by maximizing sharpness， Optics Letters，Vol，25，No．4，February 15，2000
[27] F．Berizzi and G．Corsini，Autofocusing of Inverse Synthetic Aperture Radar Images Using Contrast Optimization，IEEE Trans. Aerospace Electron， 1185-1191． 1996
[28] D.Blacknell, A.P. Blake, C.J. Oliver and R.G. White, A Comparison of BAR Multilook Registration and Contrast Optimization Autofocus Algorithms Applied to Real SAR Data, Radar'92 Conference(IEE Publication 365) , Oct.12,1992,363-366
[29] P.H.Eichel, and C.V.Jakowatz, Phase-gradient algorithm as optimal estimator of phase drivative, Optics Letters, Vol.14, No.1, Oct. 15, 1989
[30] D.E.Wahl, P.H. Eichel, D.C.Ghiglia, and C.V.Jakowatz, Phase Gradient Autofocus-A Robust Tool for High Resolution SAR Phase Correction, IEEE Trans. On Aerospace and Electronic systems, Vol.30, No.3, July 1994