If the receiver board does not allow access to the raw ephemeris data, a less accurate

clock correction is computed with a first order polynomial using time parameters obtained from the GPS almanac.

We introduced Kalman filter (Strang and Borre, 1997) in the final phase of data processing for dynamic recursive estimation of set of unknown parameters--site coordinates, correction to initial ambiguities and actual receiver clock correction.

Besides the static site coordinates are computed also the real-valued corrections to initial ambiguities, troposphere zenith delays for selected time intervals (usually 1 or 2 hours) and receiver clock corrections.

The object of the activity is to design develop and validate/verified a GNSS space receiver capable to perform on board precise orbit determination (P2OD) in real time using precise GNSS orbit and

clock corrections provided either by Geostationary satellites (thus allowing on board autonomy w.

Clock corrections are given as offsets to the Broadcast Ephemeris satellite clock corrections (http://igs.

Furthermore Hadas and Bosy (2014) stated that estimation of GLONASS clock corrections require further development.

Satellite antenna phase center offsets were not corrected because the applied orbit and clock corrections are referred to the satellite's antenna phase center.

The StarFire system uses a network of more than 50 GPS reference stations around the world to compute GPS-satellite orbit and

clock corrections.

The examples are: single-station, single-epoch, single-satellite GNSS observations; single-epoch, single-satellite GNSS navigation message; single-epoch, single-satellite orbit and clock corrections etc.

Station coordinates and receiver clock corrections were designed as stochastic processes driven by white noise.

01 for GNSS observations and broadcast ephemerides, the CLK-RINEX format for precise clock corrections and the SP3 format for precise orbit products are supported as input for the post-processing.