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分布式卫星SAR慢动目标检测及关键技术研究
【作者】 曾斌；
【导师】 黄顺吉；
【作者基本信息】 电子科技大学 ， 通信与信息系统， 2006， 博士
【摘要】 分布式卫星SAR系统是一种新概念星载SAR系统，它以小卫星群编队飞行，小卫星之间协同工作，共同完成单项或者多项任务。这种卫星组合可实现系统性能提升和功能增加，提高生存能力，提供更多的基线组合，并可实施规模生产和降低发射费用。由于分布式卫星SAR系统能够提供沿航迹基线和切航迹基线，因此能够同时实现沿航迹干涉(Along Track Interferometric：ATI)SAR和切航迹干涉SAR(Cross Track Interferometric SAR：CT-InSAR)功能。本文主要对分布式卫星SAR系统的沿航迹干涉SAR技术进行深入研究，主要工作如下。 分析了分布式星载SAR多普勒历程，研究了分布式星载SAR多普勒中心频率、多普勒调频率的计算方法，以及分布式星载SAR回波信号模型。在此基础上，建立了分布式星载SAR系统下慢动目标检测的ATI模型，分析了信号处理流程中的关键步骤，提出了一种基于去斜率处理的ATI动目标测速方法，可以减小运算量，提高运算速度。 研究了杂波和噪声影响下的ATI动目标检测技术。分析了杂波和噪声对干涉相位的影响情况，研究了相位门限法和双门限动目标检测法，并提出了一种自适应门限检测法。 研究了分布式卫星SAR系统影响测速精度的主要因素，分析并建立了相应误差模型。研究了相位噪声和测角误差对测速的影响情况；研究了卫星姿态变化对ATI测速的影响，包括基线测量、姿态变化引起的耦合相位以及切航向的速度分量等的影响，并给出了相应的精度要求；分析了地球球面效应的影响；研究了频率同步误差对干涉相位及测速的影响；建立了时间同步误差影响模型，分析了时间同步误差对干涉相位及测速的影响；得到了许多有价值的结论。 建立了分布式卫星SAR多通道动目标检测、定位和测速模型。分析了多通道条件下解速度模糊、速度方向模糊和盲速问题的方法。探讨了分布式卫星SAR系统中存在的沿航迹和切航迹混合干涉相位的分离问题，提出一种较为简单的混合干涉相位的分离方法。 本文的创新主要有： 提出了一种自适应门限检测法，解决了在噪声较大情况下，相位门限法和双门限法虚警概率较大的问题，能够较好的检测到动目标。 提出了一种结合去斜处理和短时傅立叶变换的动目标测速方法，该方法通过短时傅立叶变换，将动目标信息与杂波的分离，排除了杂波的影响，可较准确测
【Abstract】 SAR can operate at all weather and all time, and it also has certain capability of penetrating to some vegetation, which makes it widely used in many national economy aspects such as disaster and circumstance monitoring, so it is a very important instrument of space remote sensing. Distributed satellite SAR system is a new concept SAR system, which is combined with several satellites. The satellites work together to accomplish one or more tasks, which has equivalent function with a big satellite. The multi-satellite combination can improves system performances, add new functions, get advanced live capability, and supply more baseline combination. It can be realized by scale production, decreasing launch expense and circulating cost of the satellites.This dissertation mainly researches the along track interferometric SAR technology in the distributed satellite system, and the contributions are calculated as following.The Doppler history is analyzed of the spaceborne bistatic SAR, Doppler center frequency and Doppler FM rate computational methodsm are studied. Profits from the single SAR echo signal model, combines with the spaceborne bistatic SAR character.Set up the model of the micro satellites going with the primary, deduced particularly the velocity formula. Proposed one kind based on the slanting processing ATI algorithm to detect moving target, which reduced the operand, enhanced the operating speed.Analyzed the ATI technique in the influence of clutter and noise. First we analyze the influence of clutter to the interferometric phase, then the distribution of the phase and amplitude, and the CNR to false alarm. In this fundamental we compare the phase threshold only and the dual-threshold algorithm. Proposed one kind of auto-adapted threshold examines method.The dissertation analyzed in brief the influence of all kinds of error to ATI. Because the antennas were put in different platform, the model has inherent error. Analyzed the coupling phase because of the position offset and the influence to the velocity. Analyzed the influence of the gesture change of the satellite to the phase and brought forward the requirement to the gesture control. Analyzed the influence of the carry frequency and PRF error. Analyzed the influence of sphere effect of the Earth and amend the velocity formula. Analyzed the influence of the moving error of antennas