地球同步轨道发射/天地多基接收SAR/ISAR复杂运动舰船目标成像方法研究

In comparison with the conventional imaging radar, the geosynchronous orbit (GEO) transmission /space and ground- based multistatic reception SAR/ISAR multistatic SAR/ISAR has many advantages and potential applications. However, it is not a simple task to obtain clear radar images of the ship targets in complex movements by using the high orbit transmission /ship and shore-based reception SAR/ISAR. The conventional radar imaging approaches are not applicable, due to the complex relationship between the radar echo characteristics and the spatial distribution structure of the receiver and the transmitter of the multistatic SAR/ISAR, and the randomness of the swing of ship targets in the high sea state. In this project, a imaging model of the multistatic radar imaging model will be constructed to exploit the relationship among the multistatic angel, the equivalent radar line of sight and the two-dimensional high-resolution, and to exploit the impact of space-time phase synchronization error on imaging quality. Based on the analysis of the characteristics of the complex echo of the random swinging ship targets in multistatic SAR/ISAR, a novel method will be constructed for precise time-frequency analysis and parameter estimation, such that the motion compensation and imaging problem about the complex moving ship targets in high sea state of the GEO high orbit transmission /ship and shore-based reception SAR/ISAR used can be solved. The proposed imaging methods will be verified by using the real target echo data obtained from the field experiment. Overall, the proposed multistatic SAR/ISAR imaging method takes advantages of the wide coverage of the GEOSAR and the fine imaging ability of the ISAR, which can provide clear radar images for the identification of the maritime targets in a wide range of sea area all-weatherly.

与常规成像雷达相比，GEO发射/天地多基接收SAR/ISAR具有独特的优势和应用前景。但如何获得该新体制雷达复杂运动舰船目标清晰的雷达图像一直是一个困难的课题。由于多基地SAR/ISAR收发分置的空间结构与雷达回波特性的复杂关系，以及舰船目标在高海情下自身摆动的随机性，常规的成像方法已经不再适用。本项目欲建立该多基地雷达成像模型，以探究长时间积累下多基地角、等效雷达视线与二维高分辨的关系以及空时相位同步误差对成像质量的影响。在分析随机摆动舰船目标多基雷达复杂回波特性的基础上，构造出适于该类回波精确时频分析与参数估计的新方法,以突破GEO发射/天地多基接收SAR/ISAR高海情下复杂运动舰船目标运动补偿和成像的关键技术。本项目将通过外场试验验证成像方法，最终研究出利用GEOSAR宽覆盖和地基ISAR精细成像优势的多基地SAR/ISAR成像方法,为全天候地实现海上目标识别提供清晰的雷达图像。

本项目利用GEO发射/天地基接收SAR/ISAR获得复杂运动舰船目标清晰的雷达图像，以实现海上目标的广域监视和精确雷达成像。主要研究内容和重要结果包括：(1)针对GEO发射/天地多平台接收SAR/ISAR收发分置空间结构建立成像模型，分析了该多基地分布雷达空间构型与成像距离和方位分辨率的关系；(2) 提出了基于单基GEOSAR大孔径、弯曲轨道下高精度斜距模型的去距离-方位耦合的运动补偿和成像方法;（3）深入研究了GEO发射/岸基或船载接收双多基地ISAR 高海情下非平稳运动舰船目标回波特性，提出了具有较高时频聚集性的时频分析新方法;（4）研究了基于时频分析新方法和目标随机摆动特性的GEO发射/岸基或船载接收SAR/ISAR 舰船目标的运动补偿与成像方法;（5）研究了GEO 发射/天地多平台接收成像雷达体制空时相位同步误差对成像质量的影响；（6）为验证成像机理与运动补偿及成像算法的有效性，进行了仿真和外场试验，提出了高海情（三级以上海情）下，GEO发射/天地多平台接收SAR/ISAR复杂运动舰船目标的成像新方法。. 本项目研究的地球同步轨道发射/天地多基接收SAR/ISAR 将是未来海上目标信息获取的重要手段，对于实现快速、大范围的海域监视，保卫我国领土安全，突破重大工程应用中的瓶颈问题，具有重要科学意义。本课题所研究的时频分析新方法，除可用来实现 ISAR 非平稳运动目标的成像外，可应用在信号处理领域中所涉及信号参数估计的问题。