Simulation On Autonomous Orbit Determination Based On IGS

Satellite navigation system is a very important resources of space strategic. It is an important symbol of the national strength. With the added ranging system on the navigation system, not only can the accuracy of orbit determination be improved, survivability of satellite navigation system be enhanced in wartime, but also the defect that the ground tracking network can not been established all over the world can be made up effectively.An algorithm of autonomous orbit determination is proposed based on the study of theory and method. It is the main purpose of this thesis. In this algorithm, when the support of Operational Control Segment (OCS) is lost, the predicted orbit is conducted by the precise orbit firstly, then use the data of inter-satellite link (ISL) to improve the predicted orbit, after that, the results of time synchronization and orbit determination are obtained. And the results will be compared and analyzed with precise orbit and precise clock error of IGS.First, the feasibility of improving predicted orbit with ISL is analyzed, and the criteria for judging the improved orbit is given: improved orbit is better than the initial orbit. Then the data of ISL is simulated with IGS precise ephemeris. Lastly, the data of 30 day is predicted with precise orbit and clock error of one day, and the predicted orbit is improved by the data of ISL.The average of difference between predicted orbit and the precise is 4 meters in the 5th day predicted, and the average of difference between improved orbit and the predicted is 4.5 meters. The average of difference between predicted orbit and the precise is 22 meters in the 10th day predicted, and the average of difference between improved orbit and the predicted is 20.14 meters. The average of difference between predicted orbit and the precise is 66 meters in the 15th day predicted, and the average of difference between improved orbit and the predicted is about 48.79 meters. The average of difference between predicted orbit and the precise is 133 meters in the 20th day predicted, and the average of difference between improved orbit and the predicted is about 100.11 meters. In all cases, the difference between clock error resolved and precised clock error is less than 5 nanoseconds.