Spaceborne TOPSSAR Interferometry Simulation On High Precision Elevation Measurement Of Sea Surface

Terrain Observation by Progressive Scan(TOPS)mode is an innovative ScanSAR mode.It acquires wide swath images by steering antenna beam in azimuth direction,which also solves the scalloping effect caused by uneven weighting of the pattern.In recent years,Ocean remote sensing of Spaceborne SAR has become an important tool of ocean observation.If the TOPS mode is used for sea surface elevation measurement,both high resolution and wide swath images can be acquired.In this paper,the dynamic sea surface interferometric elevation measurement system is studied for the Spaceborne TOPSSAR mode,including raw data simulation for dynamic sea surface,TOPSSAR imaging and interferometry modules.Both coregistration algorithms and imaging algorithms are improved aimed to acquire high-precision elevation result.The system performance is evaluated too.The specific work is as follows:The second chapter studies the sea surface models,including the modeling of sea scenes and sea surface electromagnetic.The simulation of sea surface based on specific sea state parameters is studied too.The paper also gets the SAR raw data based on TOPS working principle.Based on the sea surface scene and the TOPS echo model,a dynamic sea surface echo simulation system is established.Then the paper evaluates the performance of the Spaceborne SAR system on dynamic sea surface of TOPS imaging mode.In particular,the sea state deviation is modeled.Based on this model,the theoretical sea state deviation under specific sea condition is determined.The paper gets the simulation result of dynamic sea surface interferometry processing,which is compared with the theoretical value to verify the validation of the simulation system.The third chapter studies the principle of interferometric elevation measurement of TOPS imaging mode,and gives the interferometric processing flow.The coregistration error is considered because of the wide Doppler centroid frequency bandwidth for TOPS mode.The Improved Spectral Diversity coregistration algorithm is proposed compared with the original algorithms.The fourth chapter studies the improved BP algorithm.Based on the basis of conventional BP algorithm,the main and auxiliary images are imaged in the same grid.And the interferometry phase error is analyzed.The interferometry flow of the BP algorithm is designed and the height precision is evaluated.The simulation result proved that the BP algorithm can already improve the accuracy of TOPS interferometry.