Satellite Orbit Modeling And Simulation Technology Research

It make sense to construct advanced spaceborne Synthetic Aperture Radar simulation system for developing spaceborne SAR and it's performance analysis. On account of satellite's flight path, it is a pivotal step to simulate satellite's orbit in spaceborne SAR simulation system.For computing satellite's orbit data, it needs to consider force model,earth's moving model,coordinate system,time system and so on. On the other side,the spaceborne SAR simulation system needs mass high precision orbit data. This dissertation studies on the modeling and simulation for satellite orbit for the spaceborne SAR simulation system. On the given force model, i have considered earth's moving model, such as precession, nutation, rotation, polar motion, the error of the data is smaller than 0.0001 meter compared to the data computed by STK .The main jobs of this dissertation include:1. Analyzed the structure and traits of spaceborne SAR simulation system and it's difference from airborne SAR simulation system. Researched dynamics principle of satellite orbit, the algorithm for computing orbit data in the inertial coordinates, and the method for solving Kepler's equation.2. Researched the algorithm for computing precession, nutation,earth rotate angle and polar motion,and chosed the appropriate algorithm. Researched the DE405 ephemeris's data structure, writen program to extract the data for computing nutation from DE405 ephemeris. Researched the EOP's data structure, writen program to extract the data for computing earth rotate angle and polar motion from the EOP data.3. Researched the time system and coordinates that often used in orbit computing. Analyzed the relation between those coordinates and the earth's precession, nutation, rotation and polar motion. Researched the algorithm that convert orbit data in J2000.0 inertial coordinates to the earth centered earth fixed coordinates, and the algorithm for computing longitude, latitude and altitude from orbit data in the earth centered earth fixed coordinates.4. Developed a software module for the spaceborne SAR simulation system, which simulates the satellite orbit. Tested the data by comparing to the data computed by STK, the error between them can be smaller than 0.00001 meter. The test of imaging of point target show that the error above will not affect the imaging of spaceborne SAR.5. Developed a visual interface for the orbit simulation software module.