GPS Precision Orbit Determination from Combined Ground and Space-borne Data

Satellite precision orbit determination (POD) is always one of the focuses in geodesy and geodynamics. Integrated adjustment of LEO and GPS for POD is reported. That means the orbits of GPS satellites and LEOs are determined simultaneously. At first, the mathematical description of the integrated adjustment is given. Then 6 cases are described to illuminate the contribution of LEO to GPS POD. It is shown that the improvement can reach 40 on average when 3 LEOs are included if 43 stations are used. Even if only 21 ground stations plus 3 LEOs are used for GPS orbit determination, about 5.0 cm accuracy from IGS final orbit can be achieved with only one day’s data. In this process, the along and cross components of the GPS orbit benefit much and the systematic error vanishes or diminishes. It is mainly attributed to the strengthened geometry of GPS tracking network and no tropospheric delay for space-borne GPS observations.