============================================================================= | SPOTGINS PPP ANALYSIS STRATEGY SUMMARY | ============================================================================= | Analysis Centers | Conservatoire National des Arts et Métiers (CNAM) | | | École & 0bservatoire des sciences de la Terre (EOST) | | | Observatoire Midi-Pyrénées (OMP) | | | Université de La Rochelle (ULR) | |---------------------------------------------------------------------------| | Contact people | Alvaro Santamaria (OMP) | | | e-mail: alvaro.santamaria at get.omp.eu | | | Jean-Paul Boy (EOST) | | | e-mail: jeanpaul.boy@unistra.fr | | | Joelle Nicolas (CNAM) | | | e-mail: joelle.nicolasduroy@lecnam.net | | | Médéric Gravelle (ULR) | | | e-mail: mederic.gravelle@univ-lr.fr | |---------------------------------------------------------------------------| | Software used | GINS developed at CNES | |---------------------------------------------------------------------------| | GNSS systems | GPS & GPS+Galileo after october 2018 | |---------------------------------------------------------------------------| | GNSS products | Final: daily station position series | | generated | hourly zenith wet delay series | | | twice-daily tropospheric gradient series | | | Rapid: none | | | Ultra rapid: none | |---------------------------------------------------------------------------| | Preparation date | February 20, 2024 | |---------------------------------------------------------------------------| | Modification dates| 20250310: improved description of the troposhpere | | | modeling | |---------------------------------------------------------------------------| | Effective date | January 1, 2023 | | for data analysis | | ============================================================================= ============================================================================= | MEASUREMENT MODELS | |---------------------------------------------------------------------------| | Preprocessing | Preprocessing of the GNSS data at the undifferenced | | | and single-difference level to determine cycle slip | | | events, remove outliers, eliminate short passes, and | | | fix WL ambiguities (Prairie v56) | |---------------------------------------------------------------------------| | Basic observable | Undifferenced ionosphere-free carrier phase and code | | |--------------------------------------------------------| | | Elevation angle cutoff: 8 degrees | | | Sampling rate: 5 minutes | | | Weighting: empirical post-fit elevation-dependent | | | sig0/(a+(1-a)sin(elev)) | | | sig0 = 3.5 mm for carrier phase | | | 600 mm for code | | | Phase biases: Wide-Line satellite biases from GRGS AC | | | (Loyer et al. 2012) | | | Code biases: monthly satellite-dependent GPS C1 & P2' | | | corrected to P1 & P2 using cc2noncc for | | | cross-correlation style receivers | |---------------------------------------------------------------------------| | Satellite antenna| SV-specific z-offsets & block-specific x- & y-offsets | | -center of mass | from igs20.atx antenna model | | offsets | | |---------------------------------------------------------------------------| | Satellite antenna| Block-specific nadir angle-dependent absolute PCVs | | phase center | from igs20.atx antenna model; no azimuth-dependent | | variations | corrections applied | |---------------------------------------------------------------------------| | Satellite clock | 2nd order relativistic correction for non-zero orbit | | corrections | ellipticity (-2*R*V/c) | |---------------------------------------------------------------------------| | Attitude | GPS nominal yaw attitude model (Bar-Sever, 1996) | | model | Galileo attitude according to metadata release by GSA | |---------------------------------------------------------------------------| | RHC phase | Phase wind-up applied | | rotation corr. | | |---------------------------------------------------------------------------| | Ground antenna | Absolute elevation-, azimuth- & frequency-dependent | | phase center | phase center corrections from igs20.atx model, | | offsets and | including antenna mis-orientation from sitelogs | | corrections | | |---------------------------------------------------------------------------| | Antenna radome | Correction applied if given in file igs20.atx, | | calibrations | otherwise radome effect neglected (radome => NONE) | |---------------------------------------------------------------------------| | Marker -> antenna| dN, dE, dU eccentricities from sitelogs applied to | | ARP eccentricity | compute station marker coordinates | |---------------------------------------------------------------------------| | Troposphere | Met. data input : 6h ECMWF-based zenith hydrostatic | | a priori model | and wet delays from VMF1 grids | | |--------------------------------------------------------| | | Mapping function: Vienna Mapping Function (VMF1) | | |--------------------------------------------------------| | | Horiz. grad. model: Cheng and Herring 2010 | |---------------------------------------------------------------------------| | Ionosphere | 1st order effect: ionospheric effects accounted for by | | | linear combination of dual frequency observations | | |--------------------------------------------------------| | | 2nd order effect: TEC from IGS/IGR iono grids | | |--------------------------------------------------------| | | Other effects: not corrected | |---------------------------------------------------------------------------| | Tidal | Solid Earth tide: IERS 2010 | | |--------------------------------------------------------| | | Permanent tidal term: applied in tide model, | | | NOT included in site coordinates | | |--------------------------------------------------------| | | Solid Earth pole tide: IERS 2010 | | |--------------------------------------------------------| | | Oceanic pole tide: IERS 2010 | | |--------------------------------------------------------| | | Ocean tide loading: FES2014b coefficients in CF | | | expanded by interpolation of the tidal admittances. | | |--------------------------------------------------------| | | Ocean tide geocenter: NA | | |--------------------------------------------------------| | | Atmosphere tides: not corrected | |---------------------------------------------------------------------------| | Non-tidal | Atmospheric pressure: not corrected | | loadings |--------------------------------------------------------| | | Ocean bottom pressure: not corrected | | |--------------------------------------------------------| | | Surface hydrology: not corrected | ============================================================================= ============================================================================= | REFERENCE FRAMES | |---------------------------------------------------------------------------| | Time argument | GPS time as given by observation epochs | | | All computations are done in TAI using TGPS=TAI-19s | | | to convert observation epochs to TAI | |---------------------------------------------------------------------------| | Inertial | geocentric; mean equator and equinox of 2000 Jan 1.5 | | frame | (J2000.0); only for data modeling and reduction | |---------------------------------------------------------------------------| | Terrestrial | Defined by the G20/GRG final orbit and clock products | | | consistent in origin, orientation and scale with the | | | IGS20 realization of ITRF2020 (Loyer et al. 2012). | |---------------------------------------------------------------------------| | Interconnection | Precession: IAU 1996 Precession Theory | | |--------------------------------------------------------| | | Nutation: IAU 2000 Nutation model | | |--------------------------------------------------------| | | IERS Conventions 2010 using NRO origin | | |--------------------------------------------------------| | | A priori polar motion and UT1 interpolated from | | | IERS Bulletin A | |---------------------------------------------------------------------------| | Tracking | Global | | network | | ============================================================================= ============================================================================= | ESTIMATED PARAMETERS (APRIORI VALUES AND CONSTRAINTS) | |---------------------------------------------------------------------------| | Adjustment | Weighted least-squares adjustment | |---------------------------------------------------------------------------| | Station | Solved daily. A priori values from several sources | | coordinates | | |---------------------------------------------------------------------------| | Receiver clock | Solved at each epoch | |---------------------------------------------------------------------------| | Troposphere | Zenith delay: zenith wet delay solved every hour using | | | a piecewise linear model | | |--------------------------------------------------------| | | Gradients: constant north and east horizontal delays | | | solved twice a day | |---------------------------------------------------------------------------| | Ambiguities | Fixed or adjusted | ============================================================================= ============================================================================= | REFERENCES | |---------------------------------------------------------------------------| | Bar-Sever, Y. E. (1996), "A new model for GPS yaw attitude", Journal of | | Geodesy, 70:714-723 | | | | GSA meta data: | | https://www.gsc-europa.eu/support-to-developers/galileo-satellite-metadata| | | | IERS Conventions (2010). Gérard Petit and Brian Luzum (eds.). (IERS | | Technical Note ; 36) Frankfurt am Main: Verlag des Bundesamts für | | Kartographie und Geodäsie, 2010. 179 pp., ISBN 3-89888-989-6 | | | | Loyer S., Perosanz F., Mercier F., Capdeville H., Marty J.C. (2012) | | Zero-difference GPS ambiguity resolution at CNES–CLS IGS Analysis | | Center. Journal of Geodesy. Doi: 10.1007/s00190-012-0559-2. | | | =============================================================================