Amelioration of the usage and Monitoring of GNSS Signals at PTB

The comparison of distant clocks has always been an important part of time metrology. It is important in science in general as well as in everyday applications. Signals from the satellites of the Global Positioning System (GPS) started to be used for the purpose in the early 1980s. This is of course ongoing, and the Time and Frequency Department of Physikalisch-Technische Bundeanstalt (PTB) provides GPS observation data in format RINEX (2.1 and 3.01) and CGGTTS V2E from several receivers on its public ftp-server and to the Bureau International des Poids et Mesures (BIPM). The “golden” reference receiver is still a legacy Ashtech Z12T with the designation PTBB (for RINEX) and PT02 (for CGGTTS) data. PTB also provides GLONASS observation data since a couple of years. Some were used for time comparisons between institutes collaborating with BIPM in the realization of International Atomic Time TAI. At the time of writing, however, no GLONASS data are used for establishing any link in the TAI computation. GLONASS link results are still reported on the BIPM ftp site, e. g. for comparing UTC(PTB) and UTC(SU). In these days, preparations are underway to routinely use signals from the other GNSS that have come to existence. Recently, Galileo and BeiDou have reached a status of early operation phase. In this contribution we thus report on the initial use of Galileo and BeiDou signals in PTB.