Satellite Orbit Determination Technology Based On TDOA

The research of satellite orbit determination technology has always been an important topic in the aerospace field,and it has important significance in many field such as navigation and positioning,satellite control and so on.The satellite orbit determination technologies mainly include optical,interferometric angle measurement and GPSassisted orbit determination.the passive location used for satellite orbital determination is limited,and it has a large errors,so we must continue to study.Also,the geosynchronous orbit satellite is far from the surface of the earth,and it is affected by various perturbation forces,so,the orbit determination has low accuracy.A program about a satellite orbital determination based on time difference is proposed in this paper.The experiment shows this program can get the geostationary satellites' location below 1000 m with time difference measured by three stations.The underdetermined problem of the three-station is completed mainly by the satellite orbit equation.The content of this paper includes the following points:1.The common time system and reference system in celestial motion is studied,and the conversion process of reference systems is programmed to verify the error under the IAU1980 standard.The six orbital elements of satellites which are deduced from the astrodynamic principle are studied,and it is used to build various satellite orbital models.Through contrasting various orbital models,the most suitable model of satellite orbit is selected for satellite orbital determination.2.The formula of CRB about the time difference equation to orbital elements is deduced,and CRB about the satellite's position is got from this formula by the CRB transform lemma.Then,the effects from the station's number,satellite orbital model,time difference noise,accumulate duration and sampling interval on CRB about the satellite's position are discussed by experiments.To some extent,the feasibility of the program is verified.3.The formula of the Newton method about time difference equations is deduced,and time difference equations are improved to reduce the impact of the model error on the estimation of orbital elements.An achievable scheme of satellite orbital determination,which includes four steps of initial value determination,orbital elements' calculation,orbit fitting and parameter updating,is proposed.Firstly,the accuracy of the orbital elements' estimation calculated by the Newton method is verified through the RMSE of the orbital elements' estimation.Secondly,through fitting different orbital data and changing different conditions,it is verified that the scheme of satellite orbital determination can meet requirements of the orbital accuracy.4.Proposed solutions to many problems in the algorithm of geostationary satellites orbital determination: the singularity of the information matrix is avoided when the semimajor axis is solved;adjusting the searched object to solve the problem of perigee blur caused by the near-circle orbit;using accumulation of time to increase the number of time difference equations;through extracting the observed data by overlapping,the divergence that may occur in the orbit fitting is solved.5.A visual interface was developed for the algorithm of satellite orbital determination.The interface simplifies user's operations and facilitates determining satellite's orbit.