变PRF体制星载SAR通用信号模型与处理方法研究

High-resolution wide-swath spaceborne synthetic aperture radar (SAR) has important application prospects in military reconnaissance, disaster assessment and natural resource dynamic monitoring. At present, the technology of variable pulse repetition frequency (PRF) with digital beamforming (DBF) to achieve high-resolution wide-swath SAR imaging is still in development. To achieve continuous illuminated swath, a universal and effective signal mapping model is needed to guide the design of radar system with variable PRF. Moreover, a robust signal reconstruction method is required to data processing in the system with variable PRF in low oversampling factors. This project is intended to study the key issues of avoiding discontinuous mapping in high-resolution wide-swath SAR systems. Firstly, according to the characteristics of spaceborne SAR system design with variable PRF in different applications, the general signal model of spaceborne SAR system with variable PRF is studied, and a general high-precision transform domain signal model is established. Secondly, a robust signal reconstruction method is proposed for the characteristics of signal loss and non-uniform sampling caused by different PRF variation schemes with low oversampling factors, Finally, the comprehensive theoretical analysis, simulation experiments and measured data are used to verify the proposed model and the method, which provide the technical support for the continuous development of the spaceborne SAR system with variable PRF and the project demonstration of high-resolution wide-swath SAR.

高分辨率宽幅星载合成孔径雷达（SAR）在军事侦察、灾害评估和自然资源动态监测等方面有着重要的应用前景。目前，使用距离向多波束变重频技术实现高分辨率宽幅成像的星载SAR系统仍在研究发展阶段，其中非连续测绘的是亟待解决的关键问题，不仅需要通用有效的信号映射模型以指导变重频体制系统设计，还需要稳健的信号重构方法实现低过采条件下的方位向变重频SAR数据处理。本项目拟针对高分宽幅SAR系统中非连续测绘的关键问题开展研究，首先，针对不同应用场景下变重频星载SAR系统设计的特点，开展变重频星载SAR通用信号模型研究，建立通用的高精度变换域信号模型；其次，针对低过采样情况下的信号缺失和非均匀采样特征，提出稳健的信号重构方法；最后，综合理论分析、仿真实验和实测数据完成模型和方法的验证，为变重频星载SAR技术的深入发展和高分宽幅星载SAR系统工程项目论证提供技术支撑。

星载合成孔径雷达具有全天时、全天候、全球观测能力，实现高分辨率超宽幅成像对满足许多应用需求至关重要，而非连续观测是高分宽幅成像系统亟待解决的关键问题，在基金的支持下，项目组开展了三种典型变重频星载SAR系统体制研究，包括慢变重频、参差重频、滑变重频等，主要研究内容如下：.1）从超宽幅体制和高分辨率体制星载SAR系统星地成像几何和目标回波的空、时域特征入手，构建PRI序列设计模型，并根据变重频SAR工作体制的特征，设计形成与之匹配的慢变PRI序列、阶变PRI序列，自适应迭代PRI序列等变化策略；.2）基于述构建的星载PRI序列模型，综合考虑不同序列的特征,提出了适用于超宽幅成像和高分辨率星载 SAR体制的信号处理方法；.3）开展仿真数据验证和多体制变重频机载SAR飞行试验，验证了多种体制下构建的PRI序列模型和信号处理方法有效性。.项目开展期间，累计发表标注项目编号的相关SCI源刊论文6篇，受理国家发明专利2项，授权国家发明专利1项。.