机载干涉合成孔径雷达运动补偿
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摘要
在机载干涉SAR(InSAR)系统中,由于气流等不稳定因素的影响,载机飞行过程中会发生位置偏移和姿态变化,载机位置偏移和姿态变化引起的运动误差影响雷达天线相位中心位置和雷达波束指向,从而影响SAR成像质量和InSAR高程反演精度。因而,对其进行运动补偿是保证成像质量和高程测量精度的关键。本文结合仿真和实测数据对机载InSAR运动补偿进行了系统的分析和总结。
本文首先分析了位置偏移和姿态变化对SAR成像质量和InSAR高程反演精度的影响,接着研究了基于定位定向系统(POS)测量数据和基于回波数据的运动补偿方法。
在基于POS的运动补偿方法中,利用高精度的POS测量数据获得位置偏移和姿态变化,将位置偏移和姿态变化统一等效为天线相位中心的位置变化,再按理想参考轨迹进行包络和相位补偿,并考虑地形起伏、方位空变、距离空变的影响,从而实现基于高精度POS测量数据的精确运动补偿。
实际中,考虑到POS测量精度的限制,我们进一步研究基于回波数据的运动补偿方法。由于运动误差必然会反映在雷达接收的回波数据中,从回波数据中可以估计得到多普勒参数,进而获得载机运动参数,利用估计的运动参数完成SAR运动补偿;对于InSAR基线变化引起的干涉相位误差,我们利用方位配准偏移量来估计基线沿视线方向的线性变化量和利用谱分割子孔径方法进行时变基线误差估计,从而完成InSAR的运动补偿。
Subject to unstable disturbances, such as atmospheric turbulence, an airborne SAR interferometry (InSAR) platform may deviate from a nominal, straight-line track with its attitude variance. The unstable movements of an airborne InSAR platform lead to defocused radar images and degraded Digital Elevation Model (DEM) accuracy. Therefore, it is necessary to compensate the motion errors. The focus of this dissertation is on analyzing the motion compensation of airborne InSAR using simulation and practical data.
In this dissertation, the effects of position and attitude errors on the SAR image quality and DEM accuracy are first analyzed, and then two strategies based on the accurate POS data and the echo data are investigated to compensate the motion errors.
For the method based on the POS data, the location and attitude variations are equivalent to the position deviation of the antenna phase centre (APC) from the ideal straight-line track, and then the envelope and the phase are compensated to the ideal reference track, taking account of the effects of the topography, azimuth and range dependence.
In practical case, considering the limitation of POS accuracy, the compensation based on the echo data is investigated. The motion parameters can be estimated from the received echo data by using the Doppler parameter estimation techniques, and the motion compensation is then carried out. For the interferometric phase errors caused by the time-varying baseline, two methods based on the registration error and the spectral diversity are investigated to compensate the InSAR motion compensation.
本文首先分析了位置偏移和姿态变化对SAR成像质量和InSAR高程反演精度的影响,接着研究了基于定位定向系统(POS)测量数据和基于回波数据的运动补偿方法。
在基于POS的运动补偿方法中,利用高精度的POS测量数据获得位置偏移和姿态变化,将位置偏移和姿态变化统一等效为天线相位中心的位置变化,再按理想参考轨迹进行包络和相位补偿,并考虑地形起伏、方位空变、距离空变的影响,从而实现基于高精度POS测量数据的精确运动补偿。
实际中,考虑到POS测量精度的限制,我们进一步研究基于回波数据的运动补偿方法。由于运动误差必然会反映在雷达接收的回波数据中,从回波数据中可以估计得到多普勒参数,进而获得载机运动参数,利用估计的运动参数完成SAR运动补偿;对于InSAR基线变化引起的干涉相位误差,我们利用方位配准偏移量来估计基线沿视线方向的线性变化量和利用谱分割子孔径方法进行时变基线误差估计,从而完成InSAR的运动补偿。
Subject to unstable disturbances, such as atmospheric turbulence, an airborne SAR interferometry (InSAR) platform may deviate from a nominal, straight-line track with its attitude variance. The unstable movements of an airborne InSAR platform lead to defocused radar images and degraded Digital Elevation Model (DEM) accuracy. Therefore, it is necessary to compensate the motion errors. The focus of this dissertation is on analyzing the motion compensation of airborne InSAR using simulation and practical data.
In this dissertation, the effects of position and attitude errors on the SAR image quality and DEM accuracy are first analyzed, and then two strategies based on the accurate POS data and the echo data are investigated to compensate the motion errors.
For the method based on the POS data, the location and attitude variations are equivalent to the position deviation of the antenna phase centre (APC) from the ideal straight-line track, and then the envelope and the phase are compensated to the ideal reference track, taking account of the effects of the topography, azimuth and range dependence.
In practical case, considering the limitation of POS accuracy, the compensation based on the echo data is investigated. The motion parameters can be estimated from the received echo data by using the Doppler parameter estimation techniques, and the motion compensation is then carried out. For the interferometric phase errors caused by the time-varying baseline, two methods based on the registration error and the spectral diversity are investigated to compensate the InSAR motion compensation.
引文
[1] Farrel J.L. Effection of navigation errors in maneuvering SAR[J]. IEEE Trans. Aeros. and Electro. Syst., 1973, 9(5): 750-776.
[2] Kirk J. C. Motion compensation for SAR[J]. IEEE Trans. Aeros. and Electro. Syst.,1975, 11(3): 338-348.
[3] Moreira A. Huang Y. Airborne SAR processing of highly squinted data using a Chirp Scaling approach with integrated motion compensation[J]. IEEE Trans Geosc. and Remote Sens., 1994, 32(5): 1029-1039.
[4] Moreira J.R. A new method of aircraft motion error extraction from radar raw data for real time motion compensation[J]. IEEE Trans. Geosci. Remote Sensing, 1990,28(4): 620-626.
[5] Wahl D.E, Eichel P.H, Ghiglia D.C. Phase gradient autofocus - a robust tool for high resolution SAR phase correction[J]. IEEE Trans. Aerosp. Electron. Syst.,1994, 30(3): 827-834.
[6] Madsen S.N.,et a1. Topographic M apping Using Radar Interferometry:Processing Techniques.IEEE Transactions on Geoscience and Remote Sensing,1993,31(1):246~ 256.
[7] Stevens,D.R.,et a1 . Options for Airborne Interferometric SAR Motion Compensation,IEEE Transactions on Oeoscience and Remote Sensing,1995,33(2):409～420.
[8] Bullock R.j.,Brennan P.V.,Griffiths H.D. Two-look roll compensation for aircraft-borne interferometric SAR without phase unwrapping[J].Electroics Letters 17th,2005,41(6);367-368.
[9] Reigber.A. Correction of residual motion errors in airborne SAR interferometry,”IEE Electron .Lett.,vol 37,no.17,pp.1083-1084.Aug.2001.
[10] Parts.P and.Mallorqui J.J. Estimation of azimuth phase undulations with multisquint processing in airborne interferometric SAR images.IEEE Trans.Geosci.Remote Sensing,vol.41,no.6,PP.1530-1533,June 2003.
[11]保铮,邢孟道,王彤.雷达成像技术[M] .北京:电子工业出版社, 2005.
[12] Scheiber Rolf and Robert.Paulraj. Origin and Correction of Phase Errors in Airborn Airborne Repeat-Pass SAR Interferometry.IEEE.2001.
[13] Reigber.A, Parts P and Mallorqui.J.J. Refined estimate of time-varyingbaseline errors in airborne SAR[J] IEEE Geosci and Remote Sensing letters,vol.3,no.1,January 2006.
[14] Soumekh.M. Synthetic Aperture Radar Signal Processing.New York:John wiley &. Sons,INC,1999.
[15] Stevens D.R.,Cumming I.G. and Gray A.L. Options for airborne interferometric SAR motion compensation[J]. IEEE Trans Geosci. Remote Sensing, 1995, 33(2):409-420.
[16] Scheiber R. A three-step phase correction approach for airborne repeat-pass interferometric SAR data[C]. in Proc. IGARSS, vol.2, Toulouse, France, 2003,pp. 1190-1192.
[17] Prats P, Reigber A and Mallorqui J. Topography-Dependent motion compensation for repeat-pass interferometric SAR systems[J].IEEE Geosci.Remote Sensing Lett., 2005, 2(2): 206-210.
[18] Macedo K and Scheiber R. Precise Topography and aperture-dependent motion compensation for airborne SAR[J]. IEEE Geosci. Remote Sensing Lett., 2005,2(2): 172-176.
[19] Cumming I.G. and Wong F. H. Digital Processing of Synthetic Aperture Radar Data Algorithms and Implementation. Norwood, MA: Artech House, 2005.
[20] Cumming I.G. A spatially selective approach to Doppler estimation for frame-based satellite SAR processing. IEEE Trans. Geosci. Remote Sens., vol. 42, no. 6, pp. 1135-1148, Jun. 2004.
[21] Cumming I.G. and Li.S.. Improved Slope Estimation for SAR Doppler Ambiguity Resolution. IEEE Trans. Geosci. Remote Sens., vol. 44, no. 3, pp. 707-718, Mar. 2006.
[22] Madsen S..N. Speckle theory: modelling, analysis, and applications related to synthetic aperture radar data[D]. Ph.D.thesis (report LD62), Electromagnetics Institute.Lyngby, Denmark.Nov.1986.
[23] Reigber A.,Scheiber P. and Mallorqui J.J. Options for High-Precision Motion compensation for Airborne Differential SAR Interferometry.IEEE.2003.
[24] Madsen S.N. Estimating the Doppler Centroid of SAR Data[J]. IEEE Trans.on.AES, 1989, 25(2): 134-140.
[25] Li F. K.,Held D.N., Curlander J., and Wu C. Doppler parameter estimation for spaceborne synthetic aperture radars. IEEE Trans. Geosci. Remote Sens., vol. GE-23, no. 1, pp. 47-56, Jan. 1985.
[26] Madsen S. N. Estimating the Doppler centroid of SAR data. IEEE Trans. Aerosp. Electron. Syst., vol. 25, no. 2, pp. 134-140, Mar. 1989.
[27] Bamler R. Doppler frequency estimation and the Cramer-Rao Bound[J]. IEEE Trans.on.GRS, 1991, 29(3): 385-389.
[28] Bamler R. and Runge H., PRF-ambiguity resolving by wavelength diversity, IEEE.Trans.Geosci.Remote.Sens.vol.29,no.6,pp 997-1003,Nov.1991.
[29] Cumming I.G.,shu Li. Adding sensitivity to the MBLF Doppler Centroid Estimator[J]. IEEE Transactions.on. GRS,VOL.45,NO.2,February 2007.
[30] Li F K., Held D. N., Curlander J. C., Wu C. Doppler Parameter Estimation for Spacebome Synthetic Aperture Radars[J]. IEEE Trans.on.GRS, 1985, 23(3): 47-56.
[31] Wahl D.E., Eichel P. H, Ghiglia D. C, Jakowatz C. V. Jr. Phase Gradient Autofocus-a Robust Tool for High Resolution SAR Phase Correction[J]. IEEE Trans.on.AES, 1994, 30(3): 827-835.
[32] Reigber A. Correction of residual motion error in airborne SAR interferometry.IEEE Electron.Lett.,vol.37,no.17,pp.1083-1084,Aug.2001.
[33] Scheiber.R and Moreira.A. Coregistration of interferometric SAR images using spectral diversity.IEEE Trans Geosci. Remote Sensing,vol.38,Sept.2000.
[34] Prats P., Reigber A.and Mallorqui J.J. Interpolation-free coregistration and phase-correction of airborne SAR interferograms. IEEE Geosci.Remote Sens.Lett.,vol.1,no.3,pp.188-191,Jul.2004.
[35] Parts P., Reigber A. and Mallorqui J.J. Efficient Detection and Correction of Residual Motion Errors in Airborne SAR Interferometry,IEEE.2004.
[2] Kirk J. C. Motion compensation for SAR[J]. IEEE Trans. Aeros. and Electro. Syst.,1975, 11(3): 338-348.
[3] Moreira A. Huang Y. Airborne SAR processing of highly squinted data using a Chirp Scaling approach with integrated motion compensation[J]. IEEE Trans Geosc. and Remote Sens., 1994, 32(5): 1029-1039.
[4] Moreira J.R. A new method of aircraft motion error extraction from radar raw data for real time motion compensation[J]. IEEE Trans. Geosci. Remote Sensing, 1990,28(4): 620-626.
[5] Wahl D.E, Eichel P.H, Ghiglia D.C. Phase gradient autofocus - a robust tool for high resolution SAR phase correction[J]. IEEE Trans. Aerosp. Electron. Syst.,1994, 30(3): 827-834.
[6] Madsen S.N.,et a1. Topographic M apping Using Radar Interferometry:Processing Techniques.IEEE Transactions on Geoscience and Remote Sensing,1993,31(1):246~ 256.
[7] Stevens,D.R.,et a1 . Options for Airborne Interferometric SAR Motion Compensation,IEEE Transactions on Oeoscience and Remote Sensing,1995,33(2):409～420.
[8] Bullock R.j.,Brennan P.V.,Griffiths H.D. Two-look roll compensation for aircraft-borne interferometric SAR without phase unwrapping[J].Electroics Letters 17th,2005,41(6);367-368.
[9] Reigber.A. Correction of residual motion errors in airborne SAR interferometry,”IEE Electron .Lett.,vol 37,no.17,pp.1083-1084.Aug.2001.
[10] Parts.P and.Mallorqui J.J. Estimation of azimuth phase undulations with multisquint processing in airborne interferometric SAR images.IEEE Trans.Geosci.Remote Sensing,vol.41,no.6,PP.1530-1533,June 2003.
[11]保铮,邢孟道,王彤.雷达成像技术[M] .北京:电子工业出版社, 2005.
[12] Scheiber Rolf and Robert.Paulraj. Origin and Correction of Phase Errors in Airborn Airborne Repeat-Pass SAR Interferometry.IEEE.2001.
[13] Reigber.A, Parts P and Mallorqui.J.J. Refined estimate of time-varyingbaseline errors in airborne SAR[J] IEEE Geosci and Remote Sensing letters,vol.3,no.1,January 2006.
[14] Soumekh.M. Synthetic Aperture Radar Signal Processing.New York:John wiley &. Sons,INC,1999.
[15] Stevens D.R.,Cumming I.G. and Gray A.L. Options for airborne interferometric SAR motion compensation[J]. IEEE Trans Geosci. Remote Sensing, 1995, 33(2):409-420.
[16] Scheiber R. A three-step phase correction approach for airborne repeat-pass interferometric SAR data[C]. in Proc. IGARSS, vol.2, Toulouse, France, 2003,pp. 1190-1192.
[17] Prats P, Reigber A and Mallorqui J. Topography-Dependent motion compensation for repeat-pass interferometric SAR systems[J].IEEE Geosci.Remote Sensing Lett., 2005, 2(2): 206-210.
[18] Macedo K and Scheiber R. Precise Topography and aperture-dependent motion compensation for airborne SAR[J]. IEEE Geosci. Remote Sensing Lett., 2005,2(2): 172-176.
[19] Cumming I.G. and Wong F. H. Digital Processing of Synthetic Aperture Radar Data Algorithms and Implementation. Norwood, MA: Artech House, 2005.
[20] Cumming I.G. A spatially selective approach to Doppler estimation for frame-based satellite SAR processing. IEEE Trans. Geosci. Remote Sens., vol. 42, no. 6, pp. 1135-1148, Jun. 2004.
[21] Cumming I.G. and Li.S.. Improved Slope Estimation for SAR Doppler Ambiguity Resolution. IEEE Trans. Geosci. Remote Sens., vol. 44, no. 3, pp. 707-718, Mar. 2006.
[22] Madsen S..N. Speckle theory: modelling, analysis, and applications related to synthetic aperture radar data[D]. Ph.D.thesis (report LD62), Electromagnetics Institute.Lyngby, Denmark.Nov.1986.
[23] Reigber A.,Scheiber P. and Mallorqui J.J. Options for High-Precision Motion compensation for Airborne Differential SAR Interferometry.IEEE.2003.
[24] Madsen S.N. Estimating the Doppler Centroid of SAR Data[J]. IEEE Trans.on.AES, 1989, 25(2): 134-140.
[25] Li F. K.,Held D.N., Curlander J., and Wu C. Doppler parameter estimation for spaceborne synthetic aperture radars. IEEE Trans. Geosci. Remote Sens., vol. GE-23, no. 1, pp. 47-56, Jan. 1985.
[26] Madsen S. N. Estimating the Doppler centroid of SAR data. IEEE Trans. Aerosp. Electron. Syst., vol. 25, no. 2, pp. 134-140, Mar. 1989.
[27] Bamler R. Doppler frequency estimation and the Cramer-Rao Bound[J]. IEEE Trans.on.GRS, 1991, 29(3): 385-389.
[28] Bamler R. and Runge H., PRF-ambiguity resolving by wavelength diversity, IEEE.Trans.Geosci.Remote.Sens.vol.29,no.6,pp 997-1003,Nov.1991.
[29] Cumming I.G.,shu Li. Adding sensitivity to the MBLF Doppler Centroid Estimator[J]. IEEE Transactions.on. GRS,VOL.45,NO.2,February 2007.
[30] Li F K., Held D. N., Curlander J. C., Wu C. Doppler Parameter Estimation for Spacebome Synthetic Aperture Radars[J]. IEEE Trans.on.GRS, 1985, 23(3): 47-56.
[31] Wahl D.E., Eichel P. H, Ghiglia D. C, Jakowatz C. V. Jr. Phase Gradient Autofocus-a Robust Tool for High Resolution SAR Phase Correction[J]. IEEE Trans.on.AES, 1994, 30(3): 827-835.
[32] Reigber A. Correction of residual motion error in airborne SAR interferometry.IEEE Electron.Lett.,vol.37,no.17,pp.1083-1084,Aug.2001.
[33] Scheiber.R and Moreira.A. Coregistration of interferometric SAR images using spectral diversity.IEEE Trans Geosci. Remote Sensing,vol.38,Sept.2000.
[34] Prats P., Reigber A.and Mallorqui J.J. Interpolation-free coregistration and phase-correction of airborne SAR interferograms. IEEE Geosci.Remote Sens.Lett.,vol.1,no.3,pp.188-191,Jul.2004.
[35] Parts P., Reigber A. and Mallorqui J.J. Efficient Detection and Correction of Residual Motion Errors in Airborne SAR Interferometry,IEEE.2004.