GPS satellite clock estimation using global atomic clock network

We report the GPS satellite clock estimation using 20 globally distributed receivers with an external hydrogen maser atomic clock. By applying corrections for the Sagnac effect, the relativistic effect due to orbit eccentricity, tropospheric and ionospheric delays, satellite and receiver antenna phase center offsets and variations, solid earth tides, ocean tide loading, phase wind-up effect, and P1-C1 bias, our satellite clock results matches the IGS final clock product within ± 1.4 ns with comparable frequency stability for an averaging time of less than 1000 sec and a 10–30% worse frequency stability for an averaging time of greater than 1000 sec, on MJD 58244. This small atomic clock network results in a fast computation that becomes increasingly appealing when the real-time satellite orbit and clock estimation is needed and as the GNSS constellations and the GNSS signals expand.