【作者】 黄钰林；

【导师】 杨建宇；

【作者基本信息】 电子科技大学 ， 信息获取与探测技术， 2008， 博士

【摘要】 双基地SAR技术成为目前雷达技术领域的前沿研究热点。它收发分置,发射站远距离发射,接收站可以承载于小型无人机平台,近距离接收,具有反侦察、抗干扰和生存力强的特点,可以显著提高合成孔径雷达的实战效能。论文针对机载双基地SAR的关键技术,主要开展了如下工作:1)根据不同的波束指向、空间几何布局和飞行状态,研究了双基地SAR的工作模式及其特点,为回波建模提供了必要条件。针对平飞斜视工作模式,建立了回波信号模型。采用Loffeld模型,得到了回波精确的二维频谱。2)针对机载双基地SAR空间分辨率问题,根据收发站运动对目标产生的合多普勒关系,导出了双基地SAR空间分辨率数学表达式,分析了分辨率的方向,揭示了空间分辨率的主要决定因素及空变特性。3)针对机载双基地SAR时间、频率和相位同步问题,分析了同步误差对成像的影响,定量地给出了在一定分辨率条件下,同步误差的限制条件。提出了一种基于GPS的秒脉冲相位跟踪平滑技术,解决了相位跳变引起同步锁相环失锁的难题,实现了系统高稳定、高精度同步。4)针对非同步条件下收发站不关联、信号不相参的问题,提出了一种恒虚警检测-滑窗跟踪技术,解决了双基地SAR回波捕获与跟踪难题,实现了非同步回波的采集与存储。5)针对平台不规则运动和姿态扰动严重影响成像质量的问题,提出了一种配合双基地扩展CS算法的运动补偿算法,解决了双基地SAR平台运动和姿态误差引起图像散焦的难题。设计了一种高精度导航和姿态测量系统方案,为基于硬件平台的双基地SAR运动补偿技术提供了一种解决途径。6)设计了机载双基地SAR实验系统方案。突出双基地特点,采用典型工作模式,完成了成像实验,得到了国内第一幅车载、机载双基地SAR图像。验证了同步技术、成像算法和运动补偿算法的有效性。更多还原

【Abstract】 Bistatic SAR, which separates transmitting and receiving stations, has become a hot topic in radar area. Its transmitter and receiver are equipped on different platforms, which are separate with long distance. It has a number of advantages such as anti-detecting, anti-disturbing and high viability and can observably increase the efficiency in the war. To address a series of key problems for the bistatic SAR, the following work has been presented1) The airborne bistatic SAR operation modes and corresponding characteristics were studied to model radar echo, under certain conditions of different beam directions, space geometries, and flying models. Specifically, the echo for the squint range operation modes was modeled. Moreover, two-dimensional spectrum of the echo was accurately obtained by using the Loffeld model.2) Aiming at airborne bistatic SAR space resolution, mathematical expressions, directions and space-variant properties for space resolution of the airborne bistatic SAR were derived based on the Doppler characteristics of the transmitting and receiving stations. The main decisive factors and space variant characteristics of space resolution were expressed.3) Aiming at time, frequency and phase synchronization technology of airborne bistatic SAR, the impact of synchronization error on imaging was analyzed and, under the condition of a certain resolution, the error bounds were quantitatively derived. A pulse per second phase tracking smoothing technology using Global Position System (GPS) was proposed to deal with synchronization PLL missing lock caused by phase agile, and realize high stability and high accuracy synchronization.4) Considering non-association of transmitting and receiving stations and non-coherence of signals under the condition of non-synchronization, a Constant False Alarm Rate (CFAR) sliding-window tracking technology was proposed to capture and track the bistatic SAR echo, and realize non-synchronized echo acquisition and storage. 5) Towards irregular motion of platforms and the problem that disturbances of the attitude affect imaging quality, a motion compensation algorithm based on the bistatic extended Chirp Scanling (CS) algorithm was proposed. This method solves the problem of image focus out by flats motion and attitude disturbance on bistatic SAR. An airborne bistatic SAR high precision navigation and attitude measurement project were designed, providing a technical method for the airborne bistatic SAR motion compensation technology based on hardware platform.6) An experimental project on the airborne bistatic SAR was proposed. The experiment using typical bistatic operation modes was successful to obtain bistatic images. The first vehicleborne and airborne bistatic SAR images in China were obtained. The synchronization technology, imaging method and motion compensation method were validated in this experiment.更多还原