Table 1 Multi-GNSS data processing strategy in PPP
Items | Correction model or estimation strategy |
|---|---|
Estimator | All the observation from different GNSS are processed together in sequential least squares estimator |
Observations | Ionospheric-free (IF) combination |
Signal selection | GPS: L1/L2; GLONASS: L1/L2;BDS: B1/B2 |
Elevation cutoff | 7° |
Observation weight | Elevation-dependent weight model (Gendt et al. 2003). The a priori precisions for raw pseudoranges and carrier phases are set to 3Â m and 0.03 cycles, respectively. |
Satellite orbit and clock | Precise orbit and clock products from the Center for Orbit Determination in Europe (CODE) (Dach et al. 2017) |
Satellite antenna phase center | Corrected |
Phase windup | Corrected |
Zenith Tropospheric delay | Initial model (Saastamoinen model) + piecewise constant |
Mapping function | Global Mapping Function (GMF) |
Receiver clock offset | Estimated at each epoch by a white noise process |
ISB and IFB | Estimated as constant |
Station displacement | Solid Earth tide, pole tide, ocean tide loading, the International Earth Rotation and Reference Systems Service (IERS) Convention 2010 |
Ambiguity resolution | No |