【作者】 石晓进；

【导师】 张云华；

【作者基本信息】 中国科学院研究生院（空间科学与应用研究中心） ， 计算机应用技术， 2009， 博士

【摘要】 自从1974年Graham提出了InSAR的概念之后,随着SAR硬件技术的不断进步和发展,机载和星载InSAR实验数据不断增多,已有许多学者在InSAR理论和信号处理领域进行了大量的研究。但是由于缺乏观测地区精确的DEM数据,大多数工作集中在如何依据相干系数和残差点来进行定性和定量的信号处理分析,较少针对干涉信号处理的各个步骤对均方根测高精度的影响进行研究。本论文的目的是通过建立星载交轨InSAR仿真模型,以最终高程均方差为判断依据,分析InSAR信号处理各步骤中相关算法和参数对最终高程精度的影响,并针对在InSAR仿真模型的建立和InSAR信号处理过程中遇到的问题,提出一些新的思想和解决方法。本文首先建立地球-卫星轨道模型,并基于此模型建立了星载SAR和InSAR仿真模型,针对星载和机载SAR的不同点,估计了星载SAR的有效速度参数并对仿真回波数据进行了Chirp-Scaling (CS)算法成像,获得了正确的InSAR干涉条纹图。随后主要研究了InSAR信号处理关键步骤中的图像配准、相位滤波、相位解缠中各种不同算法和相关参数在不同信噪比下对最终高程精度的影响。针对在图像配准步骤遇到的传统配准方法精度不高和无法计算图像对间微小旋角的问题,提出了改进的相干系数法和Fourier-Mellin变换与相干系数法相结合的InSAR图像配准新方法。在干涉相位滤波方法研究中,比较了不同信噪比下,不同滤波算法、不同滤波窗口大小的效果,得到了各信噪比下的最佳滤波窗口长度,提出应对干涉相位图分块并按各区域平均相干系数使用不同长度的滤波窗口进行滤波的算法,与此同时还研究了将不同滤波算法组合进行多次滤波的效果,得出二次滤波通常可以取得比单次滤波更好效果的结论。在相位解缠研究中,分析了各解缠算法在不同信噪比和不同滤波窗口长度下的效果,得到了不同信噪比下应优先考虑的相位解缠方法。最后对分布式卫星多基线数据融合方法进行了研究,针对最大似然多基线数据融合方法和迭代多基线数据融合方法出现的问题,提出了最大似然法与迭代法相结合的新的多基线数据融合方法,并通过仿真试验,证明该方法可以取得更好效果。更多还原

【Abstract】 Up to now since L. C. Graham proposed the concept of interferometric synthetic aperture radar (InSAR) in 1974, numerous scientists, researchers and engineers have done a lot of works on InSAR theory and signal processing, and have made significant progresses with the advancement of InSAR hardware and increase of experimental data taken by both spaceborne and airborne systems. However many of them focuses on how to process the data and analyze the results qualitatively and quantitatively with correlation coefficients and residues, less of them focus on the accuracy issues, i.e. root-mean-square (rms) of height measurment involved in different processing steps because of lack of accurate (Digital Elevation Model) DEM data in experimental areas. The purpose of the dissertation is to build a spaceborne InSAR simulation model and analyze algorithms and parameters in key steps of InSAR signal processing in view of rms of height measurement based on our simulation model, some new algorithms and ideas have been proposed.The main work of dissertation is to firstly build a spaceborne SAR and InSAR simulation model based on orbital dynamics. According to the difference between airborne and spaceborne SAR imaging, the effective velocity must be estimated in the spaceborne SAR because the spaceborne Chirp Scaling algorithm need the parameter to take place of the satellite track velocity. After the spaceborne InSAR simulation model is correctly established and the right interferograms are obtained, analysis and discussions on height accuracy of algorithms and parameters involved in InSAR signal processing are conducted, such as InSAR image-pair registration, phase filtering and phase unwrapping. Detailed works and conclusions are summarized as follows,(1) In the issue of complex images registration, regarding to the problems of conventional InSAR images registration methods, such as inaccuracy and inability of calculation of small rotation angles between images pair, we put forward modified correlation coefficient algorithm and a new registration algorithm based on Fourier-Mellin transformation and correlation coefficient algorithm to solve the problems. We also analyze the influence of the multiple interpolations and the size of matching window on final height accuracy under different signal noise ratio (SNR).(2) In issue of noise filtering of interferogram, we firstly compare the effects of six common filtering algorithms with different window size of filter and then obtain the best filtering algorithm and the best window size of filter under different SNR. Moreover, we study the performance of multi-stage filtering method and the effect of combination of different filtering algorithms. The results show that two-stage filtering always has better effect than single-stage filtering and higher-stage filtering (three stages or more) is unnecessary.(3) In issue of phase unwrapping, we discuss the typical phase unwrapping algorithms in detail, and make a comprehensive comparison among them under different SNR and window size of filter, and draw conclusion on the most appropriate phase unwrapping algorithm under different SNR.(4) Finally, we investigate the interferometric baseline combination issue of longer length with shorter length formed by distributed satellites InSAR system. In view of the problems of maximum likehood multi-baseline data fusion method and iterative multi-baseline data fusion method, we propose a new multi-baseline data fusion algorithm by combining the advantages of maximum likehood and iterative methods. Our simulation show that the new algorithm performs much well than the above two methods do.更多还原