Table 2 Processing strategy for multi-GNSS POD
From: Orbit and clock products for quad-system satellites with undifferenced ambiguity fixing approach
Items | Strategies |
|---|---|
Observation model | Â |
Observations | Undifferenced IFC pseudo-range and carrier phaseGPS: L1/L2; Galileo: E1/E5a; BDS: B1I/B3I; GLONASS: L1/L2 |
A prior noise | Pseudo-range: 0.6, 0.6, 0.6, and 3.0Â m for GPS, Galileo, BDS, and GLONASS, respectively Carrier phase: 0.01 cycles |
Weighting | Elevation-dependent weighting with 7° cutoff |
POD arc | 24Â h arc length, 300Â s sampling |
Satellite antenna | igs14.atx |
Receiver antenna | igs14.atx |
Phase-windup effect | Corrected |
Tropospheric delay | The priori delays are computed with Saastamoinen model (Saastamoinen, 1972) and Global Mapping Function (Böhm et al., 2006); then, the residual delays are estimated as piecewise constant function every 2 h |
Station coordinates | Tightly constraint to IGS weekly solutions |
Dynamic model | Â |
Earth gravity field | 12 × 12 EGM2008 model (Pavlis et al., 2012) |
N-body gravitation | Planetary and lunar ephemeris DE 421 (Folkner et al., 2009) |
Ocean tides | FES 2004 (Lyard et al., 2006) |
Solid earth and pole tides | IERS conventions 2010 (Luzum & Petit, 2012) |
Relativity effect | IERS conventions 2010 |
Antenna thrust | Correct (Steigenberger et al., 2018) |
Solar radiation pressure | GPS/GLONASS: ECOM2; BDS: ECOM; Galileo: ECOM + the a prior box-wing model |
Estimated parameters | Â |
Estimator | Sequential least square adjustment |
Initial state | Satellite position and velocity at initial epoch |
Dynamic parameters | SRP parameters |
Satellite clock offset | Epoch-wisely estimated as white noise |
Receiver clock offset | Epoch-wisely estimated as white noise; Estimate ISB of Galileo, BDS-3, BDS-2, and IFB of GLONASS channels as constants |
Phase ambiguities | Constant over each continuous observation arc |
Earth rotation parameters | Estimating Xpole, DXpole, Ypole, DYpole, DUT1, with UT1 fixed |