基于距离DBF的星载低冗余多通道高分辨宽测绘带SAR成像研究

Spaceborne multiple channel (MC) high resolution and wide swath (HRWS) synthetic aperture radar (SAR) plays an important role in the mapping, environment and disaster monitoring and so on. However, the HRWS SAR systems suffer from several problems, e.g. a huge amount of data samples, difficulties to handle complicated terrains, and channel mismatch, etc. Considering the development tendency of HRWS SAR and the difficulties faced by the state-of-the-art methods, the project will: 1) build the imaging mode of the spaceborne low redundancy MC-HRWS SAR system combined with digital beamforming (DBF) technique in elevation, and optimize the system parameters to further reduce the data redundancy; 2) by use of convex optimization and sparse direction-of-arrival estimation, develop high resolution imaging algorithms suited to the scenes with complicated terrain, and evaluate the imaging performance; 3) analyze the factors of channel errors and the effects on the images, and design the channel error estimation and compensation algorithm suited to the scenes with complicated terrain. Through the studies, the project will propose high resolution MC-HRWS SAR imaging algorithms, with better adaptation to complicated terrain, limited snapshots and low signal to noise ratio (SNR), and provide theoretical basis for the implementation of spaceborne low redundancy MC-HRWS SAR systems.

星载多通道（MC）高分辨宽测绘带（HRWS）合成孔径雷达（SAR）在地形测绘、环境及灾害监视等领域发挥着重要作用，然而HRWS SAR成像系统和处理方法面临着回波数据量大、难以适应复杂地形和通道不一致性等问题。本课题将结合HRWS SAR发展趋势，针对现有方法面临的困难，拟研究：1）结合距离数字波束形成（DBF）技术，建立星载低冗余MC-HRWS SAR成像模型，优化系统参数，进一步降低回波数据量；2）引入凸优化和稀疏空间谱估计等方法，研究适用于复杂地形的高精度成像方法，并评估其成像性能指标；3）分析通道误差的因素及影响，结合凸优化和稀疏学习等方法，研究适用于复杂地形下的距离通道误差估计与补偿算法。拟通过本项目的研究，提出高精度的MC-HRWS SAR成像算法，克服现有方法受复杂地形、小样本和低信噪比等的影响，为星载低冗余MC-HRWS SAR系统的实现和应用提供理论依据和算法基础。

本项目针对国土测量、环境及灾害监视等对HRWS SAR成像的应用需求和传统HRWS SAR成像面临的数据冗余、复杂地形、通道误差等问题，开展了基于俯仰DBF的星载低冗余HRWS SAR成像理论和方法的研究工作。主要研究内容为：1）建立了低冗余成像模型，利用整个天线阵面分时发射窄波束信号，然后各个接收通道同时接收回波，这样可大大降低回波数据量，同时分析了复杂地形对回波信号的影响；2）针对复杂地形的情况，利用稀疏谱估计方法，实现了适用于复杂地形的高精度成像算法，并分析其成像性能指标；3）针对系统可能存在的通道误差，构建了俯仰多通道误差模型，并提出了通道误差估计方法。本项目突破了复杂地形下的HRWS SAR成像和通道误差估计等关键技术，为星载低冗余HRWS SAR成像系统的研制和应用奠定了理论基础。在本项目的支持下，项目组总共发表SCI论文5篇，国际会议论文5篇，申请中国发明专利1项，培养硕士研究生1名，在读硕士研究生2名，在读博士2名。