Galileo E3 Total Time Delay Calibration in NTSC Time and Frequency Comparison

In order to improve the reliability of the time transfer link, Bureau International des Poids et Mesures (BIPM) has offcially taken the Galileo time comparison as the backup link for UTC calculation since 2020. Therefore, Galileo calibration of receiver is a necessary work for all timekeeping labs around the world to participate in the UTC link. Taking the GPS link calibrated by Physikalisch-Technische Bundesanstalt (PTB) and the National Time Service Center (NTSC) as reference, this paper sets PT09 as reference station to calibrate and verify the Galileo E3 (E1&E5a) total delay of NT02 and NT05 receivers from NTSC. The results show that the Galileo E3 total delay of NT02 and NT05 are 74.6 ns and 46.5 ns, respectively, the calibration uncertainty is 3.5 ns, and the calibration delay is relatively stable. After calibration, GPS P3 and Galileo E3 Common View results between NT02/NT05 and calibrated receivers of other timekeeping labs are basically consistent. Taking the GPS P3 links comparison results as reference between NTP3 and receivers from other labs, the average deviation is less than 1.5 ns, which is within the calibration uncertainty range.