【作者】 赵俊娟；

【导师】 尹京苑；

【作者基本信息】 上海大学 ， 信号与信息处理， 2012， 博士

【摘要】 我国是地震灾害发生较为频繁的国家,地震监测和预报是国家防震减灾的核心工作。地壳在地震发生前会产生各种各样的变形,从而构成一个地壳形变场。对易发生地震的构造区域进行形变测量,是近年来预测地震的重要手段。CR-InSAR (Corner Reflector Synthetic Aperture Radar Interferometry)技术能以毫米级的精度获取地表形变信息。通过在断层等易发生地震的形变重点监测区域架设一定数量尺寸和规格严格统一的人工角反射器,CR-InSAR可实现大面积、长期性的连续高精度形变监测。关于CR-InSAR技术,过往的研究多侧重于基于CR稳定点的形变量提取算法的改进,而对人工角反射器本身的散射特性不做过多分析。事实上,系统地研究人工角反射器的散射特点,模拟反映人工角反射器散射特点的雷达散射截面(RCS)曲线是一项很有意义的工作：RCS分析的结果可以帮助选择合适的角反射器类型；指导如何在野外架设角反射器(主要包括方位角和入射角)；人工角反射器达到最大RCS值时有利于其在SAR影像上的识别,提高形变监测的精度。鉴于这些认识,论文把研究的焦点集中在RCS的模拟方法和实验验证研究上。论文系统阐述了常用的RCS预估方法,在比较了各种方法优缺点基础上,结合人工角反射器的物理特征,选择了物理光学法(PO)计算模拟人工角反射器的RCS变化曲线。应用于CR-InSAR的人工角反射器属于电大尺寸目标,采用高频近似算法-物理光学法对常用的几种人工角反射器(二面角、三角锥形三面角、矩形锥体三面角和正方形三面角)进行了RCS曲线模拟,分析了RCS值在不同尺寸、形状和角度下的变化规律。人工角反射器在制作、加工和布设和野外恶劣的自然条件下难免会产生形状的变化,影响自身的散射性能。利用PO算法,论文讨论了角度偏差、不平整度误差和打孔误差引起的RCS缩减情况。对于可能引发较大RCS缩减的物理性质,在实际操作过程中必须严格把关。京西北试验区位于首都圈内,地表干涉条件较好且有着稳定的形变速率。在该试验场内前后分期架设了34个角反射器,获取了多景ASAR影像。通过对影像上不同类型角反射器、同类型不同尺寸角反射器、相同角反射器不同时期的后向散射强度统计分析,论文验证了RCS模拟结果的可靠性,这为今后的科学布设人工角反射器试验场提供了理论指导。更多还原

【Abstract】 China is a country with frequent earthquake disaster. Earthquake monitoring and prediction is at the core of protection against and mitigation of earthquake disasters. The earth’s crust before the earthquake will produce all kinds of deformation, then form crustal deformation field. In recent years, tectonic deformation measurement in the area which is prone to earthquake is an important means to forecast the earthquake.The technique of Corner Reflector Synthetic Aperture Radar Interferometry (CR-InSAR) can obtain ground deformation information with millimeter-scale accuracy. Artificial corner reflectors set up in region of prone to earthquake su ch as default which have strictly uniform number, size and specifications. CR-I nSAR realizes large-area, long-term continuous high precision deformation moni toring using CR. However, past studies focus on improving algorithm of extrac tion deformation based on CR, and for artificial corner reflector itself scatterin g properties don’t make much analysis. In fact, it is a very significant job incl uding systematic research on scattering characteristics and simulating RCS curv e of CR. The results of the analysis RCS can help choose the right type of c orner reflector and provide guidance on how to set up CR in the fields (mainl y including azimuth and incident Angle).When RCS of artificial corner reflect or achieves maximum, it is easier to recognize CR from SAR. In view of the understanding, the paper is focusing on the simulation method to RCS and test ing its reliability based SAR images.This paper introduces the common prediction method on RCS. Compared to benefits and drawbacks of different method, we hold that physical optics is most suitable for simulating RCS of artificial corner reflector. Because artificial corner reflector is electrically large target, PO is relatively appropriate algorithm. In this paper, we simulate RCS curve of several common artificial corner reflectors such as dihedral corner reflector, triangular trihedral corner reflector, rectangular trihedral corner reflector, square trihedral corner reflector, and analyze RCS change rule in different size, shape and angle.Artificial corner reflector in production, processing and layout and field of the bad natural conditions will inevitably produce shape variation, influence their scattering characteristics. Based on PO, this paper discusses RCS shrinking caused by the deviation angle, the unevenness of error and punched by the error. Through study, in the actual operation process theses error must be strictly checks.The northwest area in Beijing is located in the capital circle where surface interference conditions are good and deformation rate is stable. In this test area, there are34corner reflectors, and many ASAR scene images have obtained. Based on SAR images, trough the analysis to CR backscatter intensity with different style, and different size but same style and different stage of one CR, we verify simulation results are reliable. These conclusions provide theoretical guidance for scientific layout artificial corner reflector in test field.更多还原