The daily mean values of x=UTC(IT)-GPS (modulo 1 s) are computed from about 850 synchronization results obtained at INRIM by multichannel GPS receivers. From these time differences, the average daily frequency departures between UTC(IT) and GPS are computed afterwards. The expanded combined uncertainty associated to the published data is 11 ns (2 σ) for the time differences and of 0,7•10E-13 (2 σ) for the frequency departures. For the time differences, both the type A (measurement uncertainty) and type B (receiver delay stability) components have been taken into account.
The date (MJD) is expressed in terms of “Modified Julian Date”, and a correspondance table with the gregorian calendar dates is available here below.
The monthly files, reported in text format (3 columns), are named INRIM_GPS_mmmyy.txt (where “mmm” stands for the first three letters of the month, and “yy” the tens and units of the year.
The file is monthly updated.