OSA在高分辨率SAR成像算法中的应用
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摘要
合成孔径雷达(SAR)是五十年代发展起来的一种高分辨率成像雷达，它结合了合成孔径原理和脉冲压缩技术，从而在距离向和方位向上获得很高的分辨率。本文首先对SAR系统两种主要的工作模式即条带模式(Stripmap)和聚束模式(spotlight)及其相应的一些成像算法做了简单的研究和介绍，然后详细介绍了重叠子孔径(Overlapped Sub-aperture Algorithm,OSA)算法的基本原理，结合极坐标格式算法(PFA)和相位梯度自聚焦(PGA)算法，对条带模式SAR回波数据进行成像处理。
论文第一章简单回顾了SAR技术的历史、现状和发展趋势，以及SAR的特点和应用范围。
论文第二章首先介绍了线性调频信号及其压缩原理，给出了相关的计算机仿真结果，然后介绍了机载条带模式SAR标准的距离-多普勒(R-D)算法以及Chirp-Scaling(CS)算法成像过程，最后给出了R-D算法和CS算法的点目标计算机仿真结果。
论文第三章对聚束模式SAR成像处理中应用相当广泛的极坐标格式成像算法(PFA)进行了详细的介绍，然后对PFA算法的成像分辨率进行了分析。
论文第四章研究了重叠子孔径(OSA)算法的基本原理，并给出了具体的推导过程和实现方法，该算法在很大程度上降低了聚束模式SAR去斜率处理后出现的系统误差项的影响。最后通过计算机仿真，验证了此算法的可行性和有效性。
论文第五章研究利用OSA算法提高聚束SAP方位成像分辨率，详细介绍了利用OSA算法对PFA算法中去斜率处理产生误差项进行补偿的原理，给出了具体的实现流程。
论文第六章研究利用OSA算法处理条带SAR数据。首先研究了条带模式SAR和聚束模式SAR之间的关系，然后结合OSA算法和PFA算法，对条带模式SAR数据进行成像处理，并指出对条带模式SAR方位向数据进行重叠子孔径划分后，可以利用FFT变换代替PFA算法中的部分或全部CZT变换。本章还研究了相位梯度自聚焦算法(PGA)的基本原理和实现流程，以及结合PGA算法的OSA算法实现方法，最后给出了Ku波段条带模式SAR实际数据成像结果。
论文第七章对全文的工作进行总结，指出有待进一步研究的问题。
Synthetic aperture radar (SAR) is a new type of high resolution imaging radar. It acquires high range resolution and high azimuth resolution by means of combining the principle of synthetic aperture and pulse compression techniques. This paper analyzes the principle of Overlapped Sub-aperture Algorithm(OSA), and presents a method for processing strip-map SAR data by using OSA combined with Polar-Format processing Algorithm(PFA).Chapter 1 reviews the history, present situation and main trend of SAR, whereafter describes its characteristic and applied domain. Chapter 2 demonstrates the theory of Linearity Frequency Modulation, and then studies the imaging algorithm of basic Range-Doppler Algorithm and Chirp-Scaling Algorithm. The computer simulation of point target are presented.Chapter 3 makes comprehensive research into PFA(polar format algorithm) which is widely used in spotlight SAR imaging processing, and presents the resolution of processed images. In Chapter 4, the principle and implementation method of Overlapped Sub-aperture Algorithm(OSA) is described in detail. By using OSA, the system errors resulting from deramp-processing of SAR data are reduced. Computer simulation indicates that the algorithm is feasible and effective.Chapter 5 presents a method of improving the imaging resolution of PFA by using OSA to compensate the system errors resulting from deramp-processing. Chapter 6 discusses the relation between spotlight SAR and stripmap SAR, and presents a method for processing stripmap SAR data by using OSA. This Chapter also demonstrates the principle of PGA, and describes a method of combining OSA with PGA. The results of SAR raw data imaging demonstrate the feasibility of this method.Chapter 7 summarizes the whole work of this thesis and points out the problems to be solved in the future.
论文第一章简单回顾了SAR技术的历史、现状和发展趋势，以及SAR的特点和应用范围。
论文第二章首先介绍了线性调频信号及其压缩原理，给出了相关的计算机仿真结果，然后介绍了机载条带模式SAR标准的距离-多普勒(R-D)算法以及Chirp-Scaling(CS)算法成像过程，最后给出了R-D算法和CS算法的点目标计算机仿真结果。
论文第三章对聚束模式SAR成像处理中应用相当广泛的极坐标格式成像算法(PFA)进行了详细的介绍，然后对PFA算法的成像分辨率进行了分析。
论文第四章研究了重叠子孔径(OSA)算法的基本原理，并给出了具体的推导过程和实现方法，该算法在很大程度上降低了聚束模式SAR去斜率处理后出现的系统误差项的影响。最后通过计算机仿真，验证了此算法的可行性和有效性。
论文第五章研究利用OSA算法提高聚束SAP方位成像分辨率，详细介绍了利用OSA算法对PFA算法中去斜率处理产生误差项进行补偿的原理，给出了具体的实现流程。
论文第六章研究利用OSA算法处理条带SAR数据。首先研究了条带模式SAR和聚束模式SAR之间的关系，然后结合OSA算法和PFA算法，对条带模式SAR数据进行成像处理，并指出对条带模式SAR方位向数据进行重叠子孔径划分后，可以利用FFT变换代替PFA算法中的部分或全部CZT变换。本章还研究了相位梯度自聚焦算法(PGA)的基本原理和实现流程，以及结合PGA算法的OSA算法实现方法，最后给出了Ku波段条带模式SAR实际数据成像结果。
论文第七章对全文的工作进行总结，指出有待进一步研究的问题。
Synthetic aperture radar (SAR) is a new type of high resolution imaging radar. It acquires high range resolution and high azimuth resolution by means of combining the principle of synthetic aperture and pulse compression techniques. This paper analyzes the principle of Overlapped Sub-aperture Algorithm(OSA), and presents a method for processing strip-map SAR data by using OSA combined with Polar-Format processing Algorithm(PFA).Chapter 1 reviews the history, present situation and main trend of SAR, whereafter describes its characteristic and applied domain. Chapter 2 demonstrates the theory of Linearity Frequency Modulation, and then studies the imaging algorithm of basic Range-Doppler Algorithm and Chirp-Scaling Algorithm. The computer simulation of point target are presented.Chapter 3 makes comprehensive research into PFA(polar format algorithm) which is widely used in spotlight SAR imaging processing, and presents the resolution of processed images. In Chapter 4, the principle and implementation method of Overlapped Sub-aperture Algorithm(OSA) is described in detail. By using OSA, the system errors resulting from deramp-processing of SAR data are reduced. Computer simulation indicates that the algorithm is feasible and effective.Chapter 5 presents a method of improving the imaging resolution of PFA by using OSA to compensate the system errors resulting from deramp-processing. Chapter 6 discusses the relation between spotlight SAR and stripmap SAR, and presents a method for processing stripmap SAR data by using OSA. This Chapter also demonstrates the principle of PGA, and describes a method of combining OSA with PGA. The results of SAR raw data imaging demonstrate the feasibility of this method.Chapter 7 summarizes the whole work of this thesis and points out the problems to be solved in the future.
引文
[1]张澄波，“综合孔径雷达：原理、系统分析与应用”，科学出版社，1989
[2]John C.Curlander, et al., "Synthetic Aperture Radar Systems and Signal Processing". John Wiley&Sons, INC.,1991
[3]刘永坦，“雷达成像技术”，哈尔滨工业大学出版社，1999
[4]J.C.Kirk, " Digital Synthetic Aperture Radar teehnology, ",IEEE International Radar Conference, 1975
[5]中科院电子所二室，“机载合成孔径雷达实时数字成像处理器通过鉴定”，电子学报，Vol．23，No．2，Feb．1995
[6]李春升，李景文，周荫清，“空载合成孔径雷达技术及展望”，电子学报，Vol．23，No．10，Oct．1995
[7]M. Soumekh, Synthetic Aperture Radar Signal Processing with MATLAB Algorithm, New York: Wiley 1999
[8]禹卫东，合成孔径雷达信号处理研究，博士论文，南京航空航天大学，1997
[9]孙泓波，顾红等，“机载合成孔径雷达成像算法研究”，系统工程与电子技术，Vol．23，No．9 2001
[10]李春升，黄岩等，“基于Chirp Sealing算法的星载SAR成像处理实现方法”电子学报，Vol．24 No．26 June 1996
[11]R.K.Raney, H.Runge,R.Bamler, I.G.Cumming and F.H.wong, "Precision SAR Processing Using Chirp Sealing",IEEE Trans.GE., Vol.32,No.4,July 1994
[12]A.Moreira, J.Mittermayer and R.Scheiber, "Extended Chirp Scaling Algorithm for Air and Spacebome SAR Data Processing In Stripmap and Imaging Modes",IEEE Trans.GE.,Vol.34,No.5,Sept.1996
[13]R.Bamler, "A Comparison of Range-Doppler and Wave-number domain SAR Focusing Algorithm",IEEE Trans.GE.,Vol.30,pp.706-713,July 1992
[14]A.Moreira. "Real-Time Synthetic Aperture Radar(SAR) Processing with a New Subaperture Approach",IEEE Trans.GE.,Vol.30,pp.714-721,1992
[15]K.H. Wu and M.R.Vant," Extensions to the Step Transform SAR Processing Technique",IEEE Trans.AES.,Vol.21,No.3,May 1985
[16]路益蕙，“机载合成孔径雷达(SAR)距离高分辨的实现”，电子学报，Vol．20，No．3，Mar．1992
[17]禹卫东，吴淑梅，“距离-多普勒方法中的几种插值算法比较”，电子与信息学报，Vol．23,No．3,May．2001
[18]Walter G.Carrara, et al., "Spotlight Synthetic Aperture Radar Signal Processing Algorithms" Norwood MA,Artech House, 1995
[19]S. I. Tsunoda, "Lynx: A high-resolution synthetic aperture radar", SPIE Aerosense 1999,Vol. 3704
[20]Giorgio Franeeschetti,Rieeardo Lanari," Synthetic Aperture Radar Processing', pp:259-271
[21]孙进平，袁运能．“CZT在聚束SAR极坐标格式成像算法中的应用”，系统工程与电子技术．Vol．24．No．10．2002
[22]王世一，“数字信号处理”，北京理工大学出版社，1997,pp：151-156
[23]程佩青，“数字信号处理教程”，清华大学出版社，1995．8，pp：241-246
[24]Doerry, A.W., "Patch Diameter Limitations due to High Chirp Rates in Focused Synthetic Aperture Radar Images",IEEE Transactions on Aerospace and Electronic Systems,No.4,October 1994 pp. 1125-1129
[25]Doerry.A.W., "Synthetic Aperture Radar Processing with Tiered Subapertures",Sandia National Laboratories Report SAND94-1390,June 1994
[26]Wahl D E, Eiehel P H, et al. Phase gradient autofoeus-a robust tool for high resolution SAR phase correction[J]. IEEE Transactions on Aerospace and Electronic Systems, 1994,30(3):827-835
[27]李立伟，毛士艺．“相位梯度自聚焦的离散域分析与实现”，北京航空航天大学学报．Vol．25 No．2 April 1999
[28]Eiehel, P., Jakowatz, C., Jr. Phase gradient autofoeus as an optimal estimator of the phase derivative. Optics Letters, Vol. 14, No.20, Oct., 1989
[29]Jakowatz, C., Jr, Wahl, D. E. Eigenveetor method for maximum-likelihood estimation of phase errors in synthetic-aperture-radar imagery. Journal of the Optical Society of America, Vol. 10 Dee, 1993
[2]John C.Curlander, et al., "Synthetic Aperture Radar Systems and Signal Processing". John Wiley&Sons, INC.,1991
[3]刘永坦，“雷达成像技术”，哈尔滨工业大学出版社，1999
[4]J.C.Kirk, " Digital Synthetic Aperture Radar teehnology, ",IEEE International Radar Conference, 1975
[5]中科院电子所二室，“机载合成孔径雷达实时数字成像处理器通过鉴定”，电子学报，Vol．23，No．2，Feb．1995
[6]李春升，李景文，周荫清，“空载合成孔径雷达技术及展望”，电子学报，Vol．23，No．10，Oct．1995
[7]M. Soumekh, Synthetic Aperture Radar Signal Processing with MATLAB Algorithm, New York: Wiley 1999
[8]禹卫东，合成孔径雷达信号处理研究，博士论文，南京航空航天大学，1997
[9]孙泓波，顾红等，“机载合成孔径雷达成像算法研究”，系统工程与电子技术，Vol．23，No．9 2001
[10]李春升，黄岩等，“基于Chirp Sealing算法的星载SAR成像处理实现方法”电子学报，Vol．24 No．26 June 1996
[11]R.K.Raney, H.Runge,R.Bamler, I.G.Cumming and F.H.wong, "Precision SAR Processing Using Chirp Sealing",IEEE Trans.GE., Vol.32,No.4,July 1994
[12]A.Moreira, J.Mittermayer and R.Scheiber, "Extended Chirp Scaling Algorithm for Air and Spacebome SAR Data Processing In Stripmap and Imaging Modes",IEEE Trans.GE.,Vol.34,No.5,Sept.1996
[13]R.Bamler, "A Comparison of Range-Doppler and Wave-number domain SAR Focusing Algorithm",IEEE Trans.GE.,Vol.30,pp.706-713,July 1992
[14]A.Moreira. "Real-Time Synthetic Aperture Radar(SAR) Processing with a New Subaperture Approach",IEEE Trans.GE.,Vol.30,pp.714-721,1992
[15]K.H. Wu and M.R.Vant," Extensions to the Step Transform SAR Processing Technique",IEEE Trans.AES.,Vol.21,No.3,May 1985
[16]路益蕙，“机载合成孔径雷达(SAR)距离高分辨的实现”，电子学报，Vol．20，No．3，Mar．1992
[17]禹卫东，吴淑梅，“距离-多普勒方法中的几种插值算法比较”，电子与信息学报，Vol．23,No．3,May．2001
[18]Walter G.Carrara, et al., "Spotlight Synthetic Aperture Radar Signal Processing Algorithms" Norwood MA,Artech House, 1995
[19]S. I. Tsunoda, "Lynx: A high-resolution synthetic aperture radar", SPIE Aerosense 1999,Vol. 3704
[20]Giorgio Franeeschetti,Rieeardo Lanari," Synthetic Aperture Radar Processing', pp:259-271
[21]孙进平，袁运能．“CZT在聚束SAR极坐标格式成像算法中的应用”，系统工程与电子技术．Vol．24．No．10．2002
[22]王世一，“数字信号处理”，北京理工大学出版社，1997,pp：151-156
[23]程佩青，“数字信号处理教程”，清华大学出版社，1995．8，pp：241-246
[24]Doerry, A.W., "Patch Diameter Limitations due to High Chirp Rates in Focused Synthetic Aperture Radar Images",IEEE Transactions on Aerospace and Electronic Systems,No.4,October 1994 pp. 1125-1129
[25]Doerry.A.W., "Synthetic Aperture Radar Processing with Tiered Subapertures",Sandia National Laboratories Report SAND94-1390,June 1994
[26]Wahl D E, Eiehel P H, et al. Phase gradient autofoeus-a robust tool for high resolution SAR phase correction[J]. IEEE Transactions on Aerospace and Electronic Systems, 1994,30(3):827-835
[27]李立伟，毛士艺．“相位梯度自聚焦的离散域分析与实现”，北京航空航天大学学报．Vol．25 No．2 April 1999
[28]Eiehel, P., Jakowatz, C., Jr. Phase gradient autofoeus as an optimal estimator of the phase derivative. Optics Letters, Vol. 14, No.20, Oct., 1989
[29]Jakowatz, C., Jr, Wahl, D. E. Eigenveetor method for maximum-likelihood estimation of phase errors in synthetic-aperture-radar imagery. Journal of the Optical Society of America, Vol. 10 Dee, 1993