Monitoring of the offset between UTC and its prediction broadcast by the GNSS

Abstract

We present a new approach to report in the Section 4 of BIPM Circular T daily values of the offset between UTC and the predictions of UTC broadcast by the GNSS, this quantity we name bUTC_GNSS. In this approach, the determination of UTC - bUTC_GNSS is based on data collected by several multi-GNSS stations in selected time laboratories worldwide. Test computations over a 7-month period from July 2022 to January 2023 show that the offset between UTC and bUTC_GNSS was between 30 and 50 ns for GLONASS, between 5 and 20 ns for BeiDou, and between -5 and +5 ns for GPS and Galileo. We derive the uncertainty on the reported values, which is 4.1 ns for BeiDou and GPS, 3.7 ns for Galileo and 6.6 ns for GLONASS and show that, over the test period, the reported values of UTC - bUTC_GNSS and the solutions obtained from each multi-GNSS station are all consistent within the 1-sigma uncertainties.