面向综合环境监测的星载SAR技术发展

针对中国微波遥感对地观测在信息维度、反演精度、观测效率和体系架构等方面存在的问题，基于国家重点研发计划“星载新体制SAR综合环境监测技术”的研究内容与成果，探讨了面向综合环境监测的若干未来星载SAR技术发展。在超大幅宽成像方面，提出分段渐变重频时序设计方案和基于最优线性无偏估计的低过采样变重频数据处理算法，实现了跨盲区大幅宽星载SAR成像；在宽幅星载SAR高灵敏度成像方面，提出中频数字波束合成高效星上实时处理架构和加权因子快速生成算法，采用16通道机载飞行试验数据验证，图像信噪比提升约112dB；在多极化星载SAR成像方面，分别提出一种简缩极化分解算法及混合全极化方位模糊抑制方法，在P/L波段机载飞行试验中得到验证；在高精度干涉SAR技术方面，提出基于改进相位补偿方案的层析SAR处理方法，利用P波段全极化层析SAR数据验证，获得优于0.9m的森林高度反演精度；在综合环境监测星座架构设计方面，针对广域地表高程、地表形变、海浪谱能量、洋流速度和生物量应用，完成品质因数达100的高分宽幅SAR卫星方案，其观测效能和观测维度较目前在轨SAR卫星有大幅提升。

Forthcoming development trend of spaceborne SAR technology for earth environment monitoring

Focusing on the problems in the microwave remote sensing earth observation in terms of information dimension，inversion accuracy，observation efficiency and system architecture，several future spaceborne SAR technologies for comprehensive environmental monitoring were discussed based on the research achievements of the national key research and development program which was named as “Earth Environment Monitoring with Advanced Spaceborne Synthetic Aperture Radar”.In terms of ultra-large-width SAR imaging，a design scheme of segmented gradual variable pulse repetition frequency（PRF）sequence and a low-oversampling variable PRF data processing algorithm based on optimal linear unbiased estimation were proposed to realize large-scale wide-area spaceborne SAR imaging across blind areas.In terms of high-sensitivity SAR imaging，an intermediate-frequency digital beamforming（DBF）efficient on-board real-time processing architecture and a rapid generation algorithm for weighting factors were proposed，and the 16-channel airborne data were used to verify that the image signal-to-noise ratio was increased by about 11.2dB.In terms of multi-polarimetric SAR imaging，a compact polarization decomposition algorithm and a hybrid full-polarization azimuth ambiguity suppression method were proposed respectively，which were verified in the P/L band airborne flight test.In terms of high-precision interferometric SAR technology，a tomographic SAR processing method based on an improved phase compensation scheme was proposed，and the P-band full-polarization tomographic SAR data was used to verify that the forest height retrieval accuracy was better than 0.9meters.In terms of comprehensive environmental monitoring constellation architecture design，for wide-area surface elevation，surface deformation，wave spectrum energy，ocean current velocity，and biomass applications，a high-resolution wide-range SAR satellite solution with a quality factor of 100 was completed，and the performance was greatly improved compared with in-orbit SAR satellites.