Design Bistatic Interferometric DEM Generation Algorithm and Its Theoretical Accuracy Analysis for LuTan-1 Satellites

LuTan-1(LT-1)is a constellation with two full-polarization L-band radar satellites designed by China,and the first satellite was scheduled to be launched in December 2021 and the second one in January 2022.The LT-1 will be operated for deformation monitoring in repeat-pass mode,and for DEM generation in bistatic mode,improving self-sufficiency of SAR data for the field of geology,earthquake,disaster reduction,geomatics,forestry and so on.In this paper,we focused on designing an algorithm for interferometric DEM generation using LT-1 bistatic satellites.The basic principle,main error sources and errors control of the DEM generation algorithm of LT-1 were systematically analyzed.The experiment results demonstrated that:①The implemented algorithm had rigorous resolution with a theoretic accuracy better than 0.03 m for DEM generation.②The errors in satellite velocity and Doppler centroid had no obvious effect on DEM accuracy and they could be neglected.While the errors in position,baseline,slant range and interferometric phase had a significant effect on DEM accuracy.And the DEM error caused by baseline error was dominated,followed by the slant range error,interferometric phase error and satellite position error.③To obtain an expected DEM accuracy of 2 m,the baseline error must be strictly controlled and its accuracy shall be 1.0 mm or better for Cross-Track and Normal-Direction component,respectively.And the slant range error and interferometric phase error shall be reasonably controlled.The research results were of great significance for accurately grasping the accuracy of LT-1 data products and their errors control,and could provide a scientific auxiliary basis for LT-1 in promoting global SAR technology progress and the generation of high-precision basic geographic data.