Processing strategies for accurate frequency comparison using GPS carrier phase

We use GPS phase and code measurements from geodetic or geodetic-like receivers to compare distant hydrogen maser clocks. We show that the frequency comparison may be accurately carried out only when using specialised processing strategies, where main attention is paid to the continuity of the comparison result. Standard strategies used in the real time massive processing of global networks, which have proven very efficient in producing accurate, e.g. geodetic and orbit results, are less adapted to the needs of the accurate comparison of primary frequency standards.