Theory and Method of Combined GPS/GLONASS Precise Point Positioning
|School||China University of Mining and Technology|
|Course||Geodesy and Survey Engineering|
|Keywords||GPS GLONASS Precise Point Positioning|
GPS Precise Point Positioning in recent years developed a satellite positioning technology, which uses precise satellite orbit and satellite clock products, dual-band measured code pseudorange and carrier phase measurements with a single receiver positioning, it can operate on a global scale, and direct access to centimeter-level accuracy of ITRF coordinates. Compared with the relative positioning, it has the advantage of not observation distance limit between stations, direct access to the station coordinates, and simple data processing. Thus have broad application prospects in the maintenance of regional high-precision coordinate frame, scientific investigation, precision dynamic navigation and positioning, and near-Earth satellite orbit determination, high-precision engineering measurements, land and resources survey. GPS as a satellite-based navigation and positioning system, its positioning accuracy and reliability to a large extent depend on the number of satellites observed. In some places, such as urban canyons, mountains, open-pit mine, the number of visible satellites is often not enough to get position solution. The solution is a good combination of GPS and GLONASS. With the advent of GLONASS precise ephemeris and satellite clock error data products, the combination of GPS / GLONASS precise point positioning has become possible. Firstly, compared both GPS and GLONASS satellite positioning system, and then discussed both GPS and GLONASS satellite system involves the precise point positioning error sources and their processing methods, the precise point positioning In addition to the need to consider the general errors such as satellite orbit errors, satellite clock error, ionospheric delay error, tropospheric delay error, receiver clock errors, multipath errors and observation noise, also need to consider some special sources of error. These sources of error, including satellite and receiver antenna phase center offset, relativistic effects, antenna phase winding, earth tide, ocean load, atmospheric load, Sager ng effect. This paper describes and compare GPS Precise Point Positioning two models of the traditional model and P1-P2-CP model, stochastic model of the stochastic model of the observations and the parameters. The paper also gives the precise point positioning in the quality control of the Kalman filter implementation. There are time differences due to both GPS and GLONASS satellite positioning system, and thus the current GPS precise point positioning model is unable to process GLONASS data. GPS Precise Point Positioning two model expansion, derived combination of GPS / GLONASS precise point positioning observation model and the stochastic model. The combined model including the combination GPS / GLONASS traditional model and combined GPS / GLONASS P1-P2-CP model. Precise satellite ephemeris and clock error data in order to evaluate the combined GPS / GLONASS precise point positioning model using IGS tracking station observation data and the IAC (Information-Analytical Centre), on a combination GPS / GLONASS traditional model, and a combination of GPS / GLONASS P1-P2-CP model spreadsheet. The spreadsheet results show that the two models are estimated to obtain three-dimensional position accuracy, the receiver clock difference zenith tropospheric wet delay are very close. To further evaluate the performance of the GPS / GLONASS combination of precise point positioning, the use of observational data of the four IGS stations compared both from of position solution convergence speed and after the position solution accuracy GPS / GLONASS combination of precise point positioning and GPS positioning results in precise point positioning static and dynamic mode alone. By comparison, when the number of GPS satellites observed more and satellite distribution reasonable increase in the GLONASS observation data on the positioning accuracy and convergence time position solution. When the GPS satellite observations to a small number, GPS / GLONASS combination of precise point positioning compared to the positioning accuracy of GPS precise point positioning can significantly improve the position solution converges and significantly shorten the convergence time.