基于动态PS的地基合成孔径雷达高精度形变测量技术研究

发布时间：2018-05-30 06:38

本文选题：合成孔径雷达 + 地基合成孔径雷达　；参考：《北京理工大学》2016年博士论文

【摘要】：作为一种新型的形变监测手段,地基合成孔径雷达(GBSAR)系统的形变测量精度能达到mm量级甚至亚mm量级,每次监测的覆盖范围能从几十米到几公里,获取的形变反演结果能够为边坡滑坡灾害的研究提供基础数据支持。正是因为存在这些优势,GBSAR形变监测技术有非常广阔的应用前景。在GBSAR形变监测技术的应用过程中,主要存在形变反演实时性和只能获取一维视线方向形变量两大问题。本文针对形变反演实时处理的问题,在高性能动态永久散射体(PS)选择、高精度误差相位补偿、动态PS实时形变反演处理三个方面开展了研究,并提出了基于动态PS理论的实时处理方法。在解决传统GBSAR形变测量技术只能反演视线方向形变量的问题时,通过引入星载多孔径干涉(MAI)理论,开展了基于GBSAR系统的二维形变测量技术研究。本文的主要研究内容和成果如下:(1)一般来说,传统的PS选择方法包括基于相关系数的PS选择方法和基于幅度离差的PS选择方法。针对使用传统PS点选择方法后,部分选出的PS点存在相位误差较大或选出的PS点集合随时间动态变化的问题,本文研究了基于幅度、相关系数和相位联合的动态PS点选择方法。为了解决PS点选择门限随场景动态变化的问题,本文利用SAR图像杂波分布理论估计SAR图像的杂波平均功率,并依据目标点的信杂比信息,自适应地确定PS点幅度选择门限。在面对PS点集合随时间动态变化的问题时,本文通过自适应调整幅度离差和幅度门限,保证PS点集合在整个观测时间内维持相对稳定。针对PS点相位质量随时间动态变化的问题,本文利用相关系数信息和相位信息对PS点集合进行分类和二次筛选,降低由部分PS点相位质量变差而给形变反演处理所带来的负面影响。(2)在GBSAR系统长时间的监测过程中,由于非理想因素的影响,系统有较大概率会出现重轨误差,进而导致零基线的观测条件难以稳定维持。针对重轨误差会降低形变反演精度的问题,本文研究了重轨误差相位和大气相位的联合补偿方法。为了建立重轨误差到干涉相位误差的函数关系,本文首先对轨道误差进行建模,推导了它对SAR成像后目标点相位误差的影响,并以此为基础,进一步提出了重轨误差转化为干涉相位误差的数学模型。为了补偿误差相位,本文以重轨误差相位模型和大气相位模型为基础,结合最小二乘理论,给出了高精度误差相位补偿方法,并且通过对仿真数据和实测数据的处理分析,验证了该方法的有效性。(3)针对GBSAR形变监测技术中对实时性的需求,本文在传统星载PS处理方法的基础上,研究了基于GBSAR系统的动态PS实时处理算法。在处理流程方面,动态PS实时处理算法并行开展PS选择处理和PS形变反演处理,并将整个处理过程划分为初始化阶段和形变反演阶段。针对长时间基线干涉图中PS点数量不足的问题时,本文采用SAR图像分组和更新主图像的方法,尽量使干涉图所对应的时间基线控制在一定范围内,来保证PS点数量不至过少。在解决由PS点状态随时间动态变化而导致某些区域无法反演形变的问题时,本文采用插值的方法,使得某些由于PS点消亡而无法计算形变量的区域也能获取形变信息。最后,通过对北京房山石矿场边坡实验、河北唐山迁安铁矿场边坡实验和山西吕梁林家坪边坡实验的实测数据处理结果进行分析,验证了基于GBSAR系统的动态PS实时处理算法具有实时高精度监测场景形变的能力。(4)针对传统GBSAR形变测量技术只能提取一维视线方向形变的限制,本文通过引入星载多孔径干涉(MAI)技术,开展了基于GBSAR模式的MAI二维形变测量技术研究。考虑到在星载模式下,几乎所有目标点都处于正侧视的观测状态,而在GBSAR模式下,部分目标点处于非正侧视的观测状态,本文首先在星载MAI理论的基础上,分别推导了GBSAR模式下正侧视目标和非正侧视目标的MAI形变反演方法,通过将这两种观测模式进行对比,发现MAI方法实际测量的是垂直于LOS方向的形变量;然后,在分析MAI方法形变反演精度的基础上,讨论了在GBSAR模式下MAI最优孔径选择问题,并且通过对SAR图像采用相干叠加处理,进一步提升了MAI形变测量精度;最后,通过实测数据处理结果的分析,验证了在GBSAR模式下利用MAI方法获取垂直于LOS方向形变的能力,对于信噪比较高且距离较近的目标,垂直于LOS方向的形变反演精度能达到mm量级甚至亚mm量级。
[Abstract]:As a new means of deformation monitoring, the deformation measurement precision of the foundation synthetic aperture radar (GBSAR) system can reach the magnitude of mm or even sub mm. The coverage range of each monitoring can be from several tens to several kilometers. The obtained deformation inversion results can provide basic data support for the study of slope landslide disaster. It is because of the existence of this method. Some advantages, GBSAR deformation monitoring technology has a very broad application prospect. In the application process of GBSAR deformation monitoring technology, there are two major problems of real-time deformation inversion and only one dimension line of sight variable. In this paper, a high performance dynamic permanent scatterer (PS) selection and high precision error are used to solve the problem of real time deformation inversion. Three aspects of differential phase compensation, dynamic PS real-time deformation inversion processing are studied, and a real-time processing method based on dynamic PS theory is proposed. In solving the problem that the traditional GBSAR deformation measurement technology can only inverse the line of sight variable, the two-dimensional shape based on the spaceborne multi aperture interference (MAI) theory is introduced, and the two-dimensional shape based on the GBSAR system is carried out. The main research contents and achievements of this paper are as follows: (1) in general, the traditional PS selection method includes the PS selection method based on the correlation coefficient and the PS selection method based on the amplitude deviation. After using the traditional PS point selection method, the partial PS points have a larger phase error or the selected PS point set with the time. In this paper, dynamic PS point selection method based on amplitude, correlation coefficient and phase combination is studied in this paper. In order to solve the dynamic change of PS point selection threshold with the scene, this paper uses the SAR image clutter distribution theory to estimate the average clutter power of the SAR image, and adaptively determines the PS according to the signal to clutter ratio information of the target point. In the face of the dynamic variation of the PS point set with time, this paper ensures the relative stability of the PS point set during the whole observation time by adjusting the amplitude and amplitude threshold adaptively. In view of the problem of the phase quality of the PS points with the time dynamic change, this paper uses the correlation coefficient information and the phase information to the PS point. The classification and two screening are used to reduce the negative effects of the phase difference on the phase quality of the PS points. (2) in the long time monitoring process of the GBSAR system, due to the influence of non ideal factors, the system has large probability of heavy rail error, which leads to the stability of the zero baseline observation conditions. The error of heavy rail can reduce the accuracy of the deformation inversion. In this paper, the joint compensation method of the error phase of heavy rail and the phase of the atmosphere is studied. In order to establish the function relation of the error of the heavy rail to the interference phase, this paper first models the orbit error and derives the effect of its effect on the phase error of the target point after SAR imaging. In order to compensate the error phase, this paper, in order to compensate the error phase, based on the phase model of the heavy rail error and the atmospheric phase model, and combined with the least square theory, gives a high precision error phase compensation method, and through the analysis of the simulation data and the measured data, it is verified. The effectiveness of this method. (3) in view of the demand for real-time in the GBSAR deformation monitoring technology, the dynamic PS real-time processing algorithm based on the GBSAR system is studied on the basis of the traditional spaceborne PS processing method. In the processing flow, the dynamic PS real-time processing algorithm is parallel to PS selection processing and PS deformation inversion processing, and the whole process is processed. The process is divided into initialization stage and deformable inversion stage. Aiming at the problem of insufficient number of PS points in long time baseline interferograms, this paper uses SAR image grouping and updating the main image to keep the time baseline corresponding to the interferogram within a certain range, to ensure that the number of PS points is not too small. At the time, the state of the PS point is resolved at any time. In this paper, the interpolation method is used to obtain the deformation information in some regions which are unable to calculate the shape variables due to the extinction of PS points. Finally, through the slope experiment of the Fangshan stone mine in Beijing, the slope experiment of the Qian'an iron ore field in Tangshan Qian'an, Hebei, and the edge of the Linjia Ping of Lvliang, Shanxi The experimental data processing results of the slope experiment are analyzed. It is proved that the dynamic PS real-time processing algorithm based on GBSAR system has the ability of real-time and high precision monitoring scene deformation. (4) in view of the limitation that the traditional GBSAR deformation measurement technology can only extract the one dimension line of sight direction deformation, this paper has introduced the spaceborne multi aperture interference (MAI) technology. Based on the GBSAR model, the MAI two-dimensional deformation measurement technology is studied. Considering that almost all target points are in the positive side view state under the spaceborne mode, and in the GBSAR mode, some target points are in the non positive side view state. In this paper, on the basis of the star borne MAI theory, the positive side view target under the GBSAR mode and the GBSAR model are derived. The MAI Deformation Inversion Method of the non positive side vision is made by comparing the two observation modes. It is found that the MAI method actually measured the shape variable perpendicular to the LOS direction. Then, on the basis of the analysis of the inversion accuracy of the MAI method, the selection of the MAI optimal aperture in the GBSAR mode is discussed, and the coherent superposition of the SAR image is adopted. With addition treatment, the accuracy of MAI deformation measurement is further improved. Finally, through the analysis of the measured data processing results, it is proved that the ability of using the MAI method to obtain the vertical deformation in the direction of LOS under the GBSAR mode is verified. For the target with high signal to noise and close distance, the accuracy of the inversion of the deformation perpendicular to the LOS direction can reach mm order of magnitude or even the sub mm order of magnitude.
【学位授予单位】：北京理工大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN958

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