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 (11)13F)ef ficient 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. 2 dB. 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/I, 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. 9 meters. 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.