Real-time Clock Estimation for Precise Orbit Determination of LEO-Satellites

In this paper, a real-time system for clock offset estimation of GPS satellites is presented. The algorithm is based on a Kalman-filter and processes undifferenced code and carrier-phase measurements of a global NTRIP tracking network. The clock offset and drift of the satellite clocks are estimated along with tracking station clock offsets, tropospheric zenith path delay and carrier-phase ambiguities. The filter algorithm and data processing scheme is presented. The accuracy of the orbit and clock product is assessed with a precise orbit determination of the TerraSar-X satellite and compared to results gained with the IGU predicted products