单脉冲前斜SAR成像信息处理技术研究

发布时间：2019-05-11 21:20

【摘要】：单脉冲前斜SAR系统通过雷达平台侧向机动使得SAR工作在前斜视模式下，进而实现目标跟踪，是解决复杂背景下对重要军事战略目标全天时、全天候精确跟踪问题的一种有效手段。单脉冲前斜SAR具有以下优点：一方面，采用二维高分辨SAR成像处理，有利于提高信杂比，并且获取的目标图像信息丰富，有利于提高复杂背景条件下的目标检测与识别能力；另一方面，采用SAR+单脉冲测角处理，不仅能够在距离、多普勒二维平面中分辨目标的各个散射点，大大降低测角闪烁误差；而且通过单脉冲处理对SAR图像的各个分辨单元进行方位与俯仰测角，可以获取目标的空间位置信息，有利于提高目标的定位和跟踪能力。本文主要针对单脉冲前斜SAR系统技术、角度信息提取方法、目标定位与跟踪方法等关键技术开展研究。论文主要工作及创新成果体现在以下几个方面：（1）研究了单脉冲前斜SAR系统技术。针对俯冲前斜SAR复杂的几何构型、分辨率非均匀的特点，对前斜SAR分辨特性进行了分析，提出了一种基于分辨椭圆的前斜SAR分辨率分析方法。基于广义模糊函数的定义，推导了斜平面上能够完备描述目标分辨特性的分辨椭圆；然后基于地距平面的成像特点，推导了地距分辨椭圆的解析表达式，获得了地距平面目标任意方向的分辨率，尤其可以得到目标沿最差方向和最优方向的分辨率；并在此基础上建立了描述系统分辨特性的误差敏感矩阵和误差敏感因子，提出了一种多参数联合约束的几何构型优化设计方法，与传统方法相比，能够反映系统分辨性能与系统参数、飞行航迹之间的约束关系，为系统几何构型优化设计提供了理论依据。（2）研究了单脉冲前斜SAR角度提取方法。针对单脉冲SAR测角中瞬时角度测量与SAR相干积累之间的矛盾，分析了角度测量误差与相干积累时间的关系，研究了SAR成像中的角度调制特性，建立了目标时变的角运动模型，提出一种基于最小全变差准则的单脉冲SAR角度估计方法，解决了单脉冲SAR时变角度测量的问题；接着分析了平台姿态扰动、SAR相干积累等引入的角度测量误差；然后针对单脉冲SAR图像中低信噪比目标测角误差大的问题，提出了一种基于SAR单脉冲角度测量和目标区域拓扑关系的多目标角度测量的方法，基于高信噪比的特显点目标，采用最小二乘准则在图像域中提取低信噪比目标的角误差，，并通过实测数据进行了验证，可以实现SAR图像中任意像素点的跟踪，有效提高了单脉冲前斜SAR的目标跟踪精度。（3）研究了单脉冲SAR目标定位与跟踪技术。单脉冲SAR可以同时获取目标的距离、多普勒、俯仰角、方位角四维信息，由于这四维信息是分别独立获取的，对目标定位时存在信息冗余问题，提出了俯冲前斜SAR条件下的多维联合定位方法，通过建立四维信息的数学模型，提取目标的定位信息，并在此基础上引入了目标的一阶角运动参数，降低了俯冲条件下高度变化和测量误差对目标定位精度的影响；并针对二维成像与一维前视跟踪方法开展了研究，分析了跟踪末段邻近目标的混叠情况，并根据飞行轨迹对方位向分辨率的影响，研究了大前斜SAR二维像与前视跟踪阶段目标一维像之间的关系，提出了基于SAR目标幅度和单脉冲角度联合估计的目标跟踪方法，实现了末端前视目标的角度跟踪。
[Abstract]:The single-pulse front-oblique SAR system makes the SAR work in the pre-strabismus mode through the lateral maneuver of the radar platform, and then the target tracking is an effective means to solve the problem of all-weather and accurate tracking under the complex background to the important military strategic target all day. The single-pulse front oblique SAR has the advantages that the two-dimensional high-resolution SAR imaging processing is adopted, the signal-to-noise ratio is improved, the acquired target image information is rich, and the target detection and identification capability under the complex background condition is improved; and on the other hand, The method not only can distinguish various scattering points of a target in a distance and a Doppler two-dimensional plane, and greatly reduces the angle-measuring flicker error by adopting the SAR + single-pulse angle-measuring process, The spatial position information of the target can be acquired, and the positioning and tracking capability of the target can be improved. In this paper, the key technologies such as single-pulse front-oblique SAR system technology, angle information extraction method, target location and tracking method are studied. The main work and innovative achievements of the paper are reflected in the following aspects: (1) The technology of single-pulse front-oblique SAR system is studied. In view of the complicated geometric configuration and non-uniform resolution of the pre-subduction oblique SAR, the resolution characteristics of the front oblique SAR are analyzed, and a resolution analysis method based on the resolution ellipse is presented. In this paper, based on the definition of generalized fuzzy function, it is deduced that the resolution ellipse of the object-resolved characteristic can be fully described on the oblique plane, and then, based on the imaging characteristics of the ground-distance plane, the analytical expression of the ground-distance-resolved ellipse is derived, and the resolution of arbitrary direction from the plane object is obtained. In this paper, the resolution of the target in the worst direction and the optimal direction can be obtained, and the error-sensitive matrix and the error-sensitive factor describing the resolution characteristics of the system are established on the basis of this, and a method for optimizing the geometric configuration of the multi-parameter joint constraint is proposed, which is compared with the traditional method. The relationship between the system resolution performance and the system parameters and the flight path can be reflected, and the theoretical basis for the optimization design of the system geometry is provided. According to. (2), the angle of the single-pulse front oblique SAR is studied. In view of the contradiction between the instantaneous angle measurement and the SAR coherent accumulation in the single pulse SAR angle measurement, the relation between the angle measurement error and the coherent accumulation time is analyzed, the angle modulation characteristic in the SAR imaging is studied, and the target time-varying angular movement is established. In this paper, a single-pulse SAR angle estimation method based on the minimum total variation criterion is proposed to solve the problem of time-varying angle measurement of single-pulse SAR, and then the introduction of the platform attitude disturbance, SAR coherent accumulation and so on is analyzed. In this paper, a method for multi-target angle measurement based on SAR single-pulse angle measurement and target area topological relation is proposed, based on the special display of the high signal-to-noise ratio, which is based on the SAR single-pulse angle measurement and the target area topological relation. The method of the invention can realize the tracking of any pixel point in the SAR image and effectively improve the target of the single-pulse front oblique SAR by using the least square criterion to extract the angular error of the low signal-to-noise ratio target in the image domain, The tracking precision is studied. (3) The target location of the single pulse SAR is studied. The single-pulse SAR can obtain the four-dimensional information of the distance, the Doppler, the pitch angle and the azimuth angle of the target at the same time, because the four-dimensional information is obtained independently, the problem of information redundancy exists when the target is positioned, and the multi-dimensional link under the condition of the pre-dive oblique SAR is proposed. The location information of the target is extracted by establishing a mathematical model of the four-dimensional information, the first-order angular motion parameter of the target is introduced, the altitude change and the measurement error of the target are reduced under the subduction condition, The influence of the precision on the accuracy is studied, the aliasing of the adjacent target in the end section is analyzed and the influence of the flight trajectory on the resolution of the azimuth is analyzed, and the one-dimensional image of the two-dimensional image of the front oblique SAR and the forward tracking stage is studied. The target tracking method based on the combination of SAR target amplitude and single pulse angle is proposed, and the end-end forward-looking target is achieved.
【学位授予单位】：北京理工大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TN957.52

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