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摘要: 双基合成孔径雷达(SAR)采用收发平台分置的方式,能够实现复杂环境下对地海面场景和目标的高分辨成像,具有配置灵活、隐蔽性好、抗干扰能力强、获取目标信息丰富等优势,在高精度遥感测绘、隐蔽成像、精确打击等多个领域具备重要应用价值。成像处理是获得双基SAR高分辨图像的关键步骤,而双基SAR的回波模型、回波特性与传统单基SAR有显著的不同,需要对处于不同模式、不同构型下的双基SAR研究相应的成像处理方法。该文分别针对机载双基SAR、高速高机动平台双基SAR、星源异构双基SAR、星载同构双基SAR等典型模式,以及双基SAR运动补偿方法和运动目标成像等方面,分别阐述和分析了其中的关键问题,并梳理了国内外相关的解决思路和研究进展,最后对双基SAR成像处理技术的未来发展趋势进行展望。Abstract: The bistatic synthetic aperture radar (SAR) system, which employs spatially separated transmitting and receiving platforms, provides high-resolution imaging of terrestrial and maritime scenes and targets in complex environments. Its advantages include flexible configuration, strong concealment capabilities, high interference resistance, and comprehensive target information acquisition, making it valuable in high-precision remote sensing mapping, covert imaging, and precision strikes. Image processing is critical for obtaining high-resolution bistatic SAR (BiSAR) images. However, the echo model and characteristics of BiSAR substantially differ from those of traditional monostatic SAR, necessitating specialized image processing methods tailored to various operational modes and configurations. This study examines key challenges and solutions for several BiSAR configurations, including airborne BiSAR, BiSAR with high-speed and highly maneuverable platforms, spaceborne heterogeneous BiSAR, and spaceborne homogeneous BiSAR. This study also addresses motion compensation approaches and moving target imaging in BiSAR systems, reviews relevant domestic and international research advancements, and provides an outlook on future trends in BiSAR image processing.
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图 28 结合多子孔径MD算法的FFBP算法对
Figure 28. Imaging results of FFBP algorithm combined with multi-aperture MD algorithm in (a)scenario 1, (b) scenario 2 and (c) scenario 3. Imaging results of FFBP trajectory estimation algorithm based on image maximum contrast in (d) scenario 1, (e) scenario 2 and (f) scenario 3
表 1 双基典型的各类构型面临的主要问题以及相对应的主要处理方法的优缺点
Table 1. Key challenges associated with various configurations and comparative analysis of corresponding solution approaches
平台类型 主要问题 处理方法 优点 缺点 共性问题 频谱模型不精确 等效单基处理 原理简单,可应用单基算法 适应小双基角场景 显式频谱模型 适应大双基角场景;可基于单基频域
算法推导,物理意义清晰推导难度大 隐式频谱法 频谱计算精确 计算效率低 通常会有二维空变 Keystone 变换 可校正距离走动任意阶空变 仅适用于线性徙动 非线性Chirp Scaling 校正高阶非线性徙动与多普勒参数空变,
可以处理弯曲轨迹参数计算复杂 极坐标格式波数域映射 二维空变同时校正 无法处理高阶空变,
适用于聚束模式ω-k二维stolt变换 二维空变同时校正,处理精度较高 频谱模型精度要求高 时域方法 处理精度高,模式适应性强 处理效率低,对位置姿态
测量精度要求高分块处理,块内忽略空变性 方法简单 处理精度差,存在分块痕迹 机载 运动误差大 利用航姿信息补偿轨迹
偏移误差无需估计误差参数 航姿信息需精准 参数估计 计算效率高 无法处理高阶误差,精度低 相位误差估计 原理简单,计算效率高 无法处理误差空变量,精度有限 轨迹重建 可以解决二维空变 同时存在同步和运动误差时重建
精度受限,效率低分块补偿 可解决同步和运动混合误差 存在分块痕迹,效率低 高速高机动平台 “停-走-停”假设失效 高精度传播时延模型 模型精度高,成像质量好 成像算法设计困难 平台存在加速度等
高阶运动通用化双基等效斜距模型 可考虑平台恒定加速运动,
频谱模型精度高加速度变化时精度差 星源异构 照射源重频低的情况下
方位频谱混叠多通道接收 聚焦效果较好,适应性强 系统复杂度高 稀疏重建 不需要对系统硬件进行改造 效率低、依赖先验 -
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