TWSTFT DATA TREATMENT FOR UTC TIME TRANSFER

摘要

TWSTFT (TW) is the primary technique of time and frequency transfers used at BIPM for the UTC/TAI generations. At present, some 19 laboratories operate a TW facility and 12 of them are officially used in practice. The latter contribute more than two-thirds of the atomic clocks and almost all the primary frequency standards to UTC and TAI. In addition to its major role, as a precise and an independent technique to GNSS, TW is used to evaluate the new GNSS techniques. In fact, all the recent GNSS techniques finally used in UTC/TAI transfers have been approved by the comparisons with TW, such as GPS P3, GPS All in View, GPS PPP, etc. A pilot study on the GLONASS time transfer is undertaking at BIPM and again TW is an indispensable tool. Unlike the earlier publications discussing the technical details in TW, this paper focuses rather on the data treatment performed at BIPM: raw data collection, detection of outliers in the raw data, the calibration, the interpolation methods, and the link comparison with other techniques, as well as the availability of the raw and treated data sets on the Web. The authors would like the transparency of BIPM work to be helpful to the whole timing communication. It is pointed in the end that TW and GPS PPP are each complementary and the combination of the two techniques will further improve the quality of the UTC time transfer.