Research On Precise Orbit Determination Of Navigation Satellites Based On Transponder Randing

The Compass is a modern Satellite Navigation System designed and developed byChina. Precise Orbit Determination (POD) of Compass satellites is an important work, Itnot only supports various technical experiments during Compass system development, butalso guarantee precise applications in navigation, positioning, timing and scientificresearch after Compass starting to operation.Different with GPS constellation, Compass constellation is made up of three types oforbit such as Medium Earth Orbit (MEO), Geostationary Earth Orbit (GEO) and InclinedGeosynchronous Synchronous Orbit (IGSO).However, the unique feature of GEO satellite such as high altitude and smallmovement make it difficult to achieve precise orbit determination, it display in follows.First, a GEO satellite is placed at an altitude of36500kilometers above the equator, iftracking stations are placed limit in small area (such as in domestic), it makes the dilutionof geometry of GEO satellite is poor. Second, the movement of GEO satellite with respectto the station on the ground is very small, therefore, the tracking geometry to GEO isalmost unchanged due to the geostationary feature of the GEO satellite, and then it isdifficult to separate some system errors such as clock error and station bias and so on. Atthe same time, in order to keep the position of GEO satellite, station-keeping maneuver isimplemented frequently, it also make trouble for orbit determination and forecasting withGEO satellite.In the early stages of the navigation system, there is only one satellite; precise orbitdetermination for single navigation satellite is needed. At this time the mature method usedin GNSS data proceeding such as single difference, double difference can not used.The research of this dissertation is focus on precise orbit determination for singleMEO navigation satellite and GEO satellite under area traction stations. Detailed work andcontributions mainly include:1. Orbit determination for GEO satellite with the mode receiving time signalsfrom their own stationFrom the principle of “the method of transponder ranging”, the mode receiving timesignals from their own station is proposed. The observation equation is derived in detail.The precise orbit determination for the Sino-1satellite using the data from6June2005to13June2005has been carried out in this work.2. Orbit determination for GEO satellite with pairs of combined observations forboth stations From the principle of “the method of transponder ranging”, the mode receiving timesignals from each other for two stations called pairs of combined observations for bothstations is proposed. The observation equation is derived in detail. The precise orbitdetermination for the Sino-1satellite using the data from6June2005to13June2005hasbeen carried out in this work..3. Orbit determination for GEO satellite using geometric methodIn order to keep the position of GEO satellite, station-keeping maneuver isimplemented frequently, in the phase of orbit maneuver of GEO satellite, statisticaldynamics orbit determination can’t be performed, and geometric method should beconsidered. Two methods are proposed, one is single point position, and the other isgeometric method of orbit determination based on polynomial fitting. Geometric method oforbit determination has been performed using single point position method.4. Short-arc orbit determination and orbit forecasting of GEO satelliteAfter orbit maneuver, statistical dynamics orbit determination needs to be done. Inorder to recover orbit quickly after maneuver, short-arc orbit determination is proposed.Short-arc orbit determinations have been conducted with different length of data:5minutes,10minutes,15minutes,30minutes,60minutes and two hours. Orbit forecastingexperiments are also conducted.5. Orbit determination for single navigation satellite Compass-M1The problem of orbit determination for single navigation satellite using navigationdata is the clock offset processing in receiver and satellite. First the method of orbitdetermination for single navigation satellite using navigation data is verified using GPSdata. And then the orbit determination for Compass-M1has been conducted under severalmodes: pseudo range with time synchronization, pseudo range smoothed by carrier phasewith time synchronization, five stations in domestic, five stations in domestic and onestation in Antarctic. The precision of orbit determination has been assessed using severalmethods as orbit residuals, orbit overlapping and SLR residuals and so on, and come tosome conclusion.