Combination of GPS and TWSTFT data for time and frequency transfer

Combining GPS and TWSTFT considerably increases the robustness of the accurate time transfer result due to the complete independence between these two spatial techniques. In this paper we present the last improvements of a time and frequency transfer method based on a least-square analysis of GPS code and carrier phase measurements in common view, constrained by TWSTFT data. The combined method developed here provides a time transfer solution which benefits from the high short-term stability and high resolution of the GPS data and the high accuracy of the TWSTFT data. It allows to solve the large day boundary discontinuities that exist in some clock solutions obtained with geodetic time transfer, but some discontinuities appear occasionally in the CV + TW solution, due to the noise and diurnal perturbation in the TWSTFT data.