Table 1 Processing strategy for POD
From: Uncombined precise orbit and clock determination of GPS and BDS-3
Item | Description |
|---|---|
Observation data | Undifferenced GPS L1/L2 and BDS-3 B1I/B3I data with sampling rate of 30 s |
Phase center corrections (PCCs) | Navigation satellites and stations: igs14.atx, where the PCO of BDS-3 satellites is recommended by IGS. The PCO of stations for BDS-3 B1I/B3I signals use the values of GPS L1/L2 frequency |
Elevation cutoff angle | 10° |
Tropospheric delay | Prior model correction + parameter estimation, one set of wet delay parameters in the zenith direction is estimated every 2 h, one set of horizontal gradients per day; the prior model uses the Saastamoinen model, and the mapping function is the GMF |
Ambiguity parameter | DD ambiguity constraint |
Satellite clock offset | White noise (selecting a ground station as reference clock) |
POD sampling rate | 300 s |
Station coordinate | Prior constraints of each component are added for the core stations of IGS14 with an uncertainty of 0.02 m and for other stations with an uncertainty of 1000 m (Ruan and Wei 2019) |
Earth gravity | EGM 2008 |
N-body gravitation | JPL DE405 |
Solid tide | IERS conventions 2003 |
Relativity effect | IERS conventions 2003 |
Earth orientation parameter | Pole coordinates and the drifts, UT1, and length-of-day. The prior values are from the IERS-released file finals2000A.data |
Solar radiation pressure | ECOM 5 parameters |
Antenna thrust | Considered for GPS |
Earth radiation pressure | Considered for GPS |