This page contains the results of the GPS FReDNet network data analysis.

Data processing was performed using the GAMIT/GLOBK software, for more informations about GAMIT/GLOBK click here.

The 24-hour RINEX data from FReDNet sites files are processed using high-precision IGS orbits. Data collection is organized to perform 30 seconds sessions (wich leads to 2880 recordings per day). Raw data are daily converted into Rinex files with an automatic processing and they are immediately accessible to all members of the GPS community through this site by anonymous ftp. Final IGS orbits, available with 7-10 days of the end of a GPS week, are used for final solutions. Preliminary solutions for network integrity checks and rapid fault monitoring are also estimated from Predicted IGS orbits (available on the same day) and from Rapid IGS orbits (available within 1 day).

Average station coordinates are estimated from 24 hours of observations using the GAMIT software developed at MIT and SIO, and the solutions are output with weakly constrained station coordinates and satellite state vectors. The weakly constrained solutions are combined using Kalman filter techniques using the GLOBK software developed at MIT that can apply tight a posteriori constraints. This helps to ensure a self-consistent reference frame for the final combined solution. The subnet solution for each day are combined assuming a common orbit to estimate weakly constrained coordinate-only solutions. These daily coordinate-only solutions are then combined with tight coordinate constraints to estimate day-to-day coordinate repeatabilities, temporal variations, and site velocities.