Use of GLONASS for UTC time transfer

At present, the applicable spatial techniques used in UTC (Coordinated Universal Time) computation are GPS, TWSTFT (Two-Way Satellite Time and Frequency Transfers) and GLONASS. To enable accuracy and robustness for the generation of UTC, a multi-technique strategy for UTC time transfer is indispensable. Over the last two decades efforts have been made to use GLONASS for accurate time transfer. The first GLONASS time link that presents in UTC was introduced in November 2009, BIPM Circular T 263.For present and future accurate time transfers, GLONASS is comparable to GPS with the same types of observations. In this paper, we first recall principles of the GNSS Common-View and All in View time transfers; we present the technical issues for the use of GLONASS in UTC, i.e. short- and long-term stabilities, frequency biases, calibration and its practical implementation. Finally, we outline the prospects for the use of GLONASS in accurate time transfer.