=============================================================================
INTERNATIONAL GNSS SERVICE
CODE Analysis Strategy Summary
=============================================================================
| Analysis Center | Center for Orbit Determination in Europe (CODE) |
| | Astronomical Institute |
| | University of Bern |
| | Sidlerstrasse 5 |
| | CH-3012 Bern |
| | Switzerland |
| | E-mail: code (at) aiub.unibe.ch (CODE AC Team) |
| | Phone: +41-31-631-8591 |
| | Fax: +41-31-631-3869 |
| | Data archive: ftp://ftp.unibe.ch/aiub/CODE/ |
| | http://www.aiub.unibe.ch/download/CODE/ |
| | Web: http://www.aiub.unibe.ch (CODE at AIUB) |
| | http://www.bernese.unibe.ch (Bernese SW)|
|---------------------------------------------------------------------------|
| Contact People | Dr. Stefan Schaer |
| | E-mail: stefan.schaer (at) aiub.unibe.ch |
| | Phone: +41-31-631-8599 (8591) |
| | Dr. Rolf Dach |
| | E-mail: rolf.dach (at) aiub.unibe.ch |
| | Phone: +41-31-631-8593 (8591) |
| | Dr. Heik Bock |
| | E-mail: heike.bock (at) aiub.unibe.ch |
| | Phone: +41-31-631-8602 (8591) |
| | Dr. Simon Lutz |
| | E-mail: simon.lutz (at) aiub.unibe.ch |
| | Phone: +41-31-631-3802 (8591) |
| | Dr. Etienne Orliac |
| | E-mail: etienne.orliac (at) aiub.unibe.ch |
| | Phone: +41-31-631-8592 (8591) |
| | Dr. Lars Prange |
| | E-mail: lars.prange (at) aiub.unibe.ch |
| | Phone: +41-31-631-3802 (8591) |
| | Dr. Daniela Thaller |
| | E-mail: daniela.thaller (at) aiub.unibe.ch |
| | Phone: +41-31-631-3802 (8591) |
|---------------------------------------------------------------------------|
| Software Used | Bernese GNSS Software Version 5.3, developed at AIUB |
|---------------------------------------------------------------------------|
| GNSS system(s) | GPS, GLONASS |
|---------------------------------------------------------------------------|
| List of CODE's | ftp://ftp.unibe.ch/aiub/AIUB_AFTP.README |
| analysis products | http://www.aiub.unibe.ch/download/AIUB_AFTP.README |
| | |
| Final Products | Files generated from three-day long-arc solutions: |
| generated for | CODwwwwn.EPH.Z GNSS ephemeris/clock data in 7 daily |
| GPS week 'wwww' | files at 15-min intervals in SP3 |
| day of week 'n' | format, including accuracy codes |
| (n=0,1,...,6) | computed from a long-arc analysis |
| day of year 'ddd' | CODwwwwn.ERP.Z GNSS ERP (pole, UT1-UTC) solution |
| year 'yy' | belonging to the COD-orbit files in |
| | IGS IERS ERP format |
| | CODwwwwn.SNX.Z GNSS daily coordinate/ERP/GC from the |
| | long-arc solution in SINEX format |
| | CODwwwwn.CLK.Z GPS satellite and receiver clock |
| | corrections at 30-sec intervals |
| | referring to the COD-orbits from the |
| | long-arc analysis in clock RINEX |
| | format |
| | CODwwwwn.CLK_05S.Z GPS satellite and receiver clock |
| | corrections at 5-sec intervals |
| | referring to the COD-orbits from the |
| | long-arc analysis in clock RINEX |
| | format |
| | CODwwwwn.TRO.Z GNSS 2-hour troposphere delay |
| | estimates obtained from the long-arc |
| | solution in troposphere SINEX format |
| | |
| | CODwwww7.ERP.Z GNSS ERP (pole, UT1-UTC) solution, |
| | collection of the 7 daily COD-ERP |
| | solutions of the week in IGS IERS ERP |
| | format |
| | CODwwww7.SUM Analysis summary for 1 week |
| | CODwwww7.SNX.Z GNSS weekly station coordinates, |
| | SATAs, GCs, and daily sets of ERPs in |
| | SINEX format stacked from the seven |
| | long-arc solutions of the week |
| | |
| | Files generated from clean one-day solutions: |
| | COFwwwwn.EPH.Z GNSS ephemeris/clock data in 7 daily |
| | files at 15-min intervals in SP3 |
| | format, including accuracy codes |
| | computed from a clean one-day solution|
| | COFwwwwn.ERP.Z GNSS ERP (pole, UT1-UTC) solution |
| | belonging to the COF-orbit files in |
| | IGS IERS ERP format |
| | COFwwwwn.SNX.Z GNSS daily coordinate/ERP/GC from the |
| | clean one-day solution in SINEX format|
| | COFwwwwn.CLK.Z GPS satellite and receiver clock |
| | corrections at 30-sec intervals |
| | referring to the COF-orbits from the |
| | clean one-day analysis in clock RINEX |
| | format |
| | COFwwwwn.CLK_05S.Z GPS satellite and receiver clock |
| | corrections at 5-sec intervals |
| | referring to the COF-orbits from the |
| | clean one-day analysis in clock RINEX |
| | format |
| | COFwwwwn.TRO.Z GNSS 2-hour troposphere delay |
| | estimates obtained from the clean |
| | one-day solution in troposphere |
| | SINEX format |
| | |
| | COFwwww7.ERP.Z GNSS ERP (pole, UT1-UTC) solution, |
| | collection of the 7 daily COF-ERP |
| | solutions of the week in IGS IERS ERP |
| | format |
| | COFwwww7.SUM Analysis summary for 1 week |
| | COFwwww7.SNX.Z GNSS weekly station coordinates, |
| | SATAs, GCs, and daily sets of ERPs in |
| | SINEX format stacked from the seven |
| | clean one-day solutions of the week |
| | |
| | Other product files: |
| | CODGddd0.yyI.Z GNSS 2-hour global ionosphere maps in |
| | IONEX format, including satellite and |
| | receiver P1-P2 code bias values |
| | CGIMddd0.yyN GNSS daily Klobuchar-style |
| | ionospheric (alpha and beta) |
| | coefficients in RINEX format |
| | P1P2yymm.DCB GNSS monthly P1-P2 code bias |
| | solutions in Bernese DCB format |
| | P1C1yymm.DCB/F GPS monthly P1-C1 code bias solutions |
| | in Bernese DCB format and in a format |
| | specific to the CC2NONCC utility |
| | |
| | Remarks: |
| | |
| | EPH: Orbit positions correspond to the estimates |
| | for the middle day of a 3-day in case of a |
| | long-arc analysis. |
| | CLK: Clock corrections are consistent with |
| | carrier phase as well as P1/P2 pseudorange |
| | measurements. |
| | CODE P1-C1 pseudorange bias values of a |
| | moving 30-day solution are considered to |
| | correct C1/X2 and C1/P2 receiver data. |
| | EPH/ERP/SNX/TRO: These products are extracted from |
| | one inversion of the normal equation based |
| | either on a long-arc or clean one-day |
| | solution. |
| | |
| | |
| Rapid Products | CODwwwwn.EPH_R GNSS/GPS ephemeris/clock data in at |
| generated daily | 15-min intervals in SP3 format, |
| | including accuracy codes computed |
| | from a long-arc analysis |
| | CODwwwwn.ERP_R GNSS ERP (pole, UT1-UTC) solution in |
| | IGS IERS ERP format |
| | CODwwwwn.CLK_R GPS satellite and receiver clock |
| | corrections at 30-sec intervals in |
| | clock RINEX format |
| | CODwwwwn.TRO_R GNSS 2-hour troposphere delay |
| | estimates in troposphere SINEX format |
| | CORGddd0.yyI GNSS 2-hour global ionosphere maps in |
| | IONEX format, including satellite and |
| | receiver P1-P2 code bias values |
| | CGIMddd0.yyN_R GNSS daily Klobuchar-style |
| | ionospheric (alpha and beta) |
| | coefficients in RINEX format |
| | CODwwwwd.SNX_R GNSS daily station coordinates and |
| | set of 6-hourly ERPs in SINEX format |
| | (for IERS inter-technique combination)|
| | |
| | Remarks: |
| | |
| | EPH: Orbit positions correspond to the estimates |
| | for the last day of a 3-day long-arc analysis. |
| | CLK: Clock corrections are consistent with carrier |
| | phase as well as P1/P2 pseudorange |
| | measurements. |
| | CODE P1-C1 pseudorange bias values of a moving |
| | 30-day solution are considered to correct |
| | C1/X2 and C1/P2 receiver data. |
| | |
| | |
| Ultra Rapid | COD.EPH_U GNSS ephemeris/broadcast clock data |
| Products updated | in at 15-min intervals in SP3 format, |
| every 6 hours | including accuracy codes computed |
| | from a long-arc analysis |
| | COD.ERP_U GNSS ERP (pole, UT1-UTC) solution |
| | in IGS IERS ERP format |
| | COD.SUM_U List of considered GNSS stations |
| | COD.TRO_U GNSS 2-hour troposphere delay |
| | estimates in troposphere SINEX format |
| | COD.ION_U GNSS 2-hour global ionosphere maps in |
| | Bernese ION format |
| | |
| | Remarks: |
| | |
| | EPH: Orbit positions correspond to the estimates |
| | for the last 24 hours of a 3-day long-arc |
| | analysis plus predictions for the following |
| | 24 hours |
| | EPH/ERP/TRO: Files contain generally results of |
| | last update |
| | ION: Last rapid ionosphere product complemented by |
| | all available ionosphere predictions |
| | |
| | |
| Predictions | CODwwwwn.EPH_Pi GNSS/GPS ephemeris/clock data at |
| updated every 6 | 15-min intervals in SP3 format, |
| hours | including accuracy codes computed |
| | from a long-arc analysis |
| | CODwwwwn.ERP_Pi GNSS ERP (pole, UT1-UTC) solution in |
| | IGS IERS ERP format |
| | COPGddd0.yyI GNSS 2-hour global ionosphere maps in |
| | IONEX format, including satellite |
| | P1-P2 code bias values |
| | CGIMddd0.yyN_Pi GNSS daily Klobuchar-style |
| | ionospheric (alpha and beta) |
| | coefficients in RINEX format |
| | CODwwwwd.EPH_5D GNSS/GPS ephemeris/clock data at |
| | 15-min intervals in SP3 format |
| | CODwwwwd.ERP_5D GNSS ERP (pole, UT1-UTC) solution |
| | in IGS IERS ERP format |
| | |
| | Remarks: |
| | |
| | "P2" indicates 2-day predictions (24-48 hours); |
| | "P" indicates 1-day predictions (0-24 hours). |
| | "5D" indicates files containing predicted |
| | information for 5 days (0-120 hours). |
| | |
| | |
| Specialties in | - CODE has been generating its products from a |
| CODE's analysis | rigorous combination of GPS and GLONASS |
| | observations. In this way, best possible |
| | consistency of the orbit products is guaranteed. |
| | - Uninterrupted POD for all transmitting GNSS |
| | satellites, specifically for: |
| | . brand new satellites |
| | . satellites without any broadcast orbit information|
| | . satellites marked unhealthy/unusable |
| | . poorly observed (GLONASS) satellites |
| | . (GPS) satellites being repositioned |
| | - Elevation mask angle of 3 degrees used. |
| | - Sophisticated ambiguity resolution scheme, already |
| | including GLONASS ambiguity resolution (with |
| | restrictions, specifically for baseline lengths |
| | longer than 200 km), self-calibrating for GLONASS. |
| | - Ambiguity verification scheme: resolved ambiguities |
| | are checked in terms of compability, also in order |
| | to detect unexpected quarter-cycle issues. |
| | - GPS quarter-cycle phase biase issue: potentially |
| | affected GPS ambiguities are banned from ambiguity |
| | resolution. |
| | - Continuous parameterization, particularly for EOP, |
| | troposphere ZPD and horizontal gradient parameters, |
| | ionosphere parameters, allowing for connection of |
| | the parameters at day boundaries. |
| | - IGS fiducial sites are automatically verified for |
| | consistent datum definition. This is also true with |
| | respect to all antenna-sharing fiducial sites. |
| | - Inclusion of fast moving South Pole station AMU2. |
| | - Inclusion of all available NGA stations. |
| | - Generation of high-rate (5-sec) clock products. |
| | - Generation of high-rate (1-hour) EOP results |
| | (internally). |
| | - Setup of GNSS satellite antenna PCV parameters |
| | specific to each individual GPS and GLONASS |
| | satellite; corresponding patterns are not only |
| | available for the ionosphere-free linear |
| | combination but also for the geometry-free (L1-L2) |
| | linear combination. |
| | - A multi-GNSS-capable internal PCV file format is |
| | used; receiver antenna PCV models specific to |
| | GLONASS (or other) frequencies are applied. |
| | - 3 terms of higher-order ionosphere (HOI) effects are|
| | taken into account (based on CODE GIM & IGRF11SYN). |
| | Scaling factor for 2nd and 3rd order HOI as well as |
| | for ray bending for validation purposes and to |
| | switch the parameter on or off |
| | - Atmospheric non-tidal pressure loading correction |
| | at observation level with scaling factors to obtain |
| | solutions without applying such corrections |
| | - Monitoring of various differential code biases |
| | (DCBs), specifically: |
| | . GPS/GLONASS P1-P2 satellite and receiver DCBs |
| | . GPS/GLONASS P1-C1 and P2-C2 satellite DCBs |
| | . biases crucial for GLONASS ambiguity resolution |
| | Values are extracted from different data processing |
| | steps and directly from the RINEX observation files |
| | (where possible) |
| | - Extensive monitoring of IGS data flow concerning: |
| | . availability |
| | . latency |
| | . completeness |
| | . consistency |
| | - SINEX loop: COD & COF SINEX results are routinely |
| | imported and re-introduced. First extracted and |
| | secondly re-produced station coordinate results are |
| | cross-checked to the original analysis results (at |
| | 0.01-mm level). The extracted list of fiducial |
| | stations is used for this re-production. |
| | - Provision of GNSS geocenter coordinates in SINEX. |
| | - Production of GNSS rapid SINEX files containing |
| | station coordinates and ERPs with a time resolution |
| | of 6 hours is foreseen as a contribution for the |
| | IERS inter-technique combination. |
| | - Regular GNSS orbit validation using SLR data; CODE |
| | acts as an AAC of the ILRS. |
| | - The latest version of our steadily further |
| | developed GNSS analysis software is employed for |
| | operational analysis. |
| | |
| Computer platform | Week 1477: UBELIX: Linux, x86_64 |
| | Week 1065: UBECX: SunOS |
| | |
| Last changes: | Week 1691: See IGSREPORT.20913 |
| | Week 1643: See IGSREPORT.19947 |
| | Week 1632: See IGSREPORT.19702 |
| | Week 1625: See IGSREPORT.19560 |
| | Week 1619: See IGSREPORT.19411 |
| | Week 1618: See IGSREPORT.19385 |
| | Week 1604: See IGSREPORT.19068 and IGSMAIL.6287 |
| | Week 1570: See IGSREPORT.18301 and IGSMAIL.6078 |
| | Week 1542: See IGSREPORT.17667 and IGSMAIL.5970 |
| | Week 1488: See IGSREPORT.16472 |
| | Week 1477: See IGSREPORT.16225 and IGSMAIL.5771 |
| | Week 1452: See IGSREPORT.15669/IGSREPORT.14622 |
| | Week 1440: See IGSREPORT.15405 |
| | Week 1439: See IGSREPORT.15403 |
| | Week 1409: See IGSREPORT.14695 |
| | Week 1406: See IGSREPORT.14622/IGSMAIL.5507 & .5518 |
| | Week 1400: See IGSREPORT.14486 and IGSMAIL.5518 |
| | Week 1367: See IGSREPORT.13669 |
| | Week 1349: See IGSREPORT.13201 |
| | Week 1328: See IGSREPORT.12706 |
| | Week 1326: See IGSREPORT.12657 |
| | Week 1321: See IGSREPORT.12569 and IGSMAIL.5151 |
| | Week 1299: See IGSREPORT.12031 |
| | Week 1282: See IGSREPORT.11617 |
| | Week 1279: See IGSREPORT.11543 |
| | Week 1255: See IGSMAIL.4913 |
| | Week 1254: See IGSREPORT.10997 and IGLOSMAIL.963 |
| | Week 1252: See IGSMAIL.4782 |
| | Week 1242: See IGSREPORT.10752 |
| | Week 1222: See IGSREPORT.10361 and |
| | IGSMAIL.4474/IGLOSMAIL.770 |
| | Week 1216: See IGSMAIL.4371/IGLOSMAIL.736 |
| | Week 1191: See IGSREPORT.9756 and IGSMAIL.4162 |
| | Week 1158: See IGSREPORT.9147 and IGSMAIL.3823 |
| | Week 1143: See IGSREPORT.8868 |
| | Week 1142: See IGSREPORT.8848 |
| | Week 1135: See IGSREPORT.8710 |
| | Week 1130: See IGSREPORT.8616 |
| | Week 1128: See IGSREPORT.8577 |
| | Week 1077: See IGSREPORT.7544 |
| | Week 1065: See IGSREPORT.7279 |
| | Week 1057: See IGSREPORT.7107 and IGSMAIL.2827 |
| | Week 1021: See IGSREPORT.6351 |
| | Week 0978: See IGSREPORT.5415 and IGSMAIL.2043 |
| | Week 0947: See IGSREPORT.4698 and IGSMAIL.1829 |
| | Week 0926: See IGSREPORT.4247 and IGSMAIL.1705 |
| | Week 0873: See IGSREPORT.3056 |
|---------------------------------------------------------------------------|
| Preparation Date | 18-Aug-1996 |
|---------------------------------------------------------------------------|
| Modification Dates| 13-Mar-1998 |
| | 12-Mar-2002/SS: Major revision and update |
| | 13-Mar-2002/SS: JGM3 model up to degree 12 |
| | 24-Oct-2002/SS: Typo concerning satellite antenna |
| | offset value corrected |
| | 28-May-2008/SS/RD: Major revision and update |
| | 13-Oct-2010/SS/RD: Processing model update |
| | 19-Dec-2012/SS: Major revision and update |
|---------------------------------------------------------------------------|
| Effective Date for| 19-Dec-2012 |
| Data Analysis | |
=============================================================================
=============================================================================
| MEASUREMENT MODELS |
|---------------------------------------------------------------------------|
| Preprocessing | Phase preprocessing in a baseline by baseline mode |
| | using triple-differences. In most cases, cycle slips |
| | are fixed looking simultaneously at different linear |
| | combinations of L1 and L2. If a cycle slip cannot be |
| | fixed reliably, bad data points are removed or new |
| | ambiguities are set up. In addition, a data screening |
| | step on the basis of weighted postfit residuals is |
| | performed. Outliers are removed. |
|---------------------------------------------------------------------------|
| Basic Observables| GPS/GLONASS carrier phase; code only used for receiver |
| | clock synchronization |
| |--------------------------------------------------------|
| | Elevation angle cutoff : 3 degrees |
| | Sampling rate : 3 minutes |
| | Weighting : 6 mm for double-differenced |
| | ionosphere-free phase |
| | observations at zenith; |
| | elevation-dependent weighting|
| | function 1/cos(z)**2 |
|---------------------------------------------------------------------------|
| Modeled | Double differences, ionosphere-free linear combination |
| observables | |
|---------------------------------------------------------------------------|
| Satellite antenna| SV-specific z-offsets & block-specific x- & y-offsets |
| -center of mass | from IGS using file igs08_wwww.atx based on ITRF2008 |
| offsets | |
|---------------------------------------------------------------------------|
| Satellite antenna| block-specific nadir angle-dependent "absolute" PCVs |
| phase center | applied from file igs08_wwww.atx; no azimuth-dependent |
| corrections | corrections applied |
|---------------------------------------------------------------------------|
| Satellite clock | 2nd order relativistic correction for non-zero |
| corrections | orbit ellipticity (-2*R*V/c) applied |
| | NOTE: Other dynamical relativistic effects under |
| | Orbit Models |
|---------------------------------------------------------------------------|
| GPS attitude | Nominal attitude implemented. |
| model | |
|---------------------------------------------------------------------------|
| RHC phase | Phase polarization effects applied (Wu et al., 1993) |
| rotation corr. | |
|---------------------------------------------------------------------------|
| Ground antenna | "absolute" elevation- & azimuth-dependent (when |
| phase center | available) PCVs & L1/L2 offsets from ARP applied from |
| offsets & | file igs08_wwww.atx |
| corrections | Receiver antenna models specific to GLONASS are |
| | applied (as far as available). |
|---------------------------------------------------------------------------|
| Antenna radome | Calibration applied if given in file igs08_wwww.atx; |
| calibrations | otherwise radome effect neglected (radome => NONE) |
|---------------------------------------------------------------------------|
| Marker -> antenna| dN, dE, dU eccentricities from site logs applied to |
| ARP eccentricity | compute station coordinates |
|---------------------------------------------------------------------------|
| Troposphere | ECMWF-based hydrostatic delay mapped with hydrostatic |
| a priori model | VMF1. Coefficients from 6-hourly global grids. |
| | |
| | Gradient model: none |
|---------------------------------------------------------------------------|
| Ionosphere | 1st order effect: eliminated by forming the |
| | ionosphere-free linear combination |
| | of L1 and L2. |
| |--------------------------------------------------------|
| | 2nd order effect: applied, IGRF11 implementation, TEC |
| | from CODE global ionosphere model |
| |--------------------------------------------------------|
| | 3rd order effect: applied, TEC from CODE global |
| | ionosphere model |
| |--------------------------------------------------------|
| | Other effects: ray bending applied, TEC from CODE |
| | global ionosphere model |
| | |
| | GNSS-derived global ionosphere map |
| | information is used to support |
| | ambiguity resolution when using the |
| | QIF strategy. |
|---------------------------------------------------------------------------|
| Tidal | Solid Earth tide : complete model from IERS |
| displacements | Conventions 2010 |
| | |
| | Step 1: in-phase: degree 2 and 3 |
| | Nominal h02 and l02 : 0.6078, 0.0847 (anela.)|
| | Nominal h22 and l22 :-0.0006, 0.0002 |
| | Nominal h3 and l3 : 0.292 , 0.015 |
| | |
| | out-of-phase: degree 2 only semi- and diurnal |
| | diurnal: nominal hI, lI :-0.0025,-0.0007 |
| | semi-di: nominal hI, lI :-0.0022,-0.0007 |
| | |
| | latitude dependence |
| | diurnal: nominal l1 : 0.0012 |
| | semi-di: nominal l1 : 0.0024 |
| | |
| | Step 2: in-phase: degree 2, diurnal |
| | in-phase and out-of-phase: long-period tides |
| |--------------------------------------------------------|
| | Permanent tide : applied in tide model, |
| | NOT included in site coordinates|
| |--------------------------------------------------------|
| | Solid Earth pole tide: applied (IERS 2010) |
| |--------------------------------------------------------|
| | Oceanic pole tide : not applied |
| |--------------------------------------------------------|
| | Ocean tide loading : IERS 2010, site-dependent amps |
| | & phases from Bos & Scherneck |
| | website for FES2004 tide model |
| | NEU site displacements computed |
| | using hardisp.f from D. Agnew |
| |--------------------------------------------------------|
| | Ocean tide geocenter : coeffs. corrected for center of |
| | mass motion of whole Earth |
| |--------------------------------------------------------|
| | Atmospheric tides : S1+S2 tidal corrections from the|
| | Vienna atmospheric pressure |
| | model |
|---------------------------------------------------------------------------|
| Non-tidal | Atmospheric pressure : Non-tidal components from the |
| loadings | Vienna atmospheric pressure |
| | model with three scaling factors|
| | per station (one for each |
| | component) for validation |
| | purposes. |
| | The product files are generated |
| | without considering the non- |
| | tidal pressure loading by |
| | forcing the scaling factors to |
| | zero. |
| |--------------------------------------------------------|
| | Ocean bottom pressure: not applied |
| |--------------------------------------------------------|
| | Surface hydrology : not applied |
| |--------------------------------------------------------|
| | Other effects : none applied |
|---------------------------------------------------------------------------|
| Earth orientation| Ocean tidal: diurnal/semidiurnal variations in x,y, & |
| variations | UT1 applied according to IERS 2010, Tables|
| | 8.2a, 8.2b, 8.3a, 8.3b |
| |--------------------------------------------------------|
| | Atmosphere tidal: S1, S2, S3 tides not applied |
| |--------------------------------------------------------|
| | High-frequency nutation: applied according to IERS |
| | 2010, Table 5.1a |
| |--------------------------------------------------------|
| | UT1 libration: applied according to IERS 2010, Table |
| | 5.1.b |
=============================================================================
=============================================================================
| REFERENCE FRAMES |
|---------------------------------------------------------------------------|
| Time argument | TDT |
| | GPS time as given by observation epochs, which is |
| | offset by only a fixed constant (approx.) from TT/TDT |
|---------------------------------------------------------------------------|
| Inertial | geocentric; mean equator and equinox of 2000 Jan 1 |
| frame | at 12:00 (J2000.0) |
|---------------------------------------------------------------------------|
| Terrestrial | ITRF2008 reference frame realized through a set of |
| frame | station coordinates and velocities given in the IGS |
| | internal realization IGb08. |
| | |
| | Datum definition: |
| | . 3 no-net translation conditions (only if geocenter |
| | is estimated) |
| | . 3 no-net rotation conditions |
| | . geocenter coordinates constrained nominally to |
| | zero values |
| | IGb08 fiducial sites are selected as reference, if: |
| | . horizontal deviation < 10 mm |
| | . vertical deviation < 30 mm |
|---------------------------------------------------------------------------|
| Tracking | Ultra-rapid with about 90, rapid with 120 and final |
| network | 270 stations per day are used. |
| | Station selection is based on long time series, |
| | contribution to existing reference frames, co-location |
| | with other space-geodetic techniques, GLONASS- |
| | capability, and all-in-view tracking support for |
| | unhealthy satellites. |
|---------------------------------------------------------------------------|
| Interconnection | Precession: IAU 2000 Precession Theory |
| |--------------------------------------------------------|
| (EOP parameter | Nutation: IAU 2000R06 Nutation Theory |
| estimation is |--------------------------------------------------------|
| below) | A priori EOPs: polar motion & UT1 from IERS C04 series |
| | aligned to ITRF2008 |
=============================================================================
=============================================================================
| ORBIT MODELS |
|---------------------------------------------------------------------------|
| Geopotential | EGM2008 model up to degree and order 12 (+C21+S21) |
| (static) |--------------------------------------------------------|
| | GM = 398600.4415 km**3/sec**2 |
| |--------------------------------------------------------|
| | AE = 6378.1363 km |
|---------------------------------------------------------------------------|
| Tidal variations | Solid Earth tides: applied according to IERS 2010 |
| in geopotential |--------------------------------------------------------|
| | Ocean tides: applied, FES2004 model |
| |--------------------------------------------------------|
| | Solid Earth pole tide: applied according to IERS 2010 |
| |--------------------------------------------------------|
| | Oceanic pole tide: applied according to IERS 2010 |
|---------------------------------------------------------------------------|
| Third-body | Sun, Moon, Jupiter, Venus, Mars as point masses |
| |--------------------------------------------------------|
| | Ephemeris: JPL DE405 |
| |--------------------------------------------------------|
| | GMsun = 132712500000 km**3/sec**2 |
| |--------------------------------------------------------|
| | GMmoon = 4902.7890 km**3/sec**2 |
|---------------------------------------------------------------------------|
| Solar radiation | A priori: CODE RPR model coefficients for GPS |
| pressure model | satellites (updated 2007) ´ |
| (parameter |--------------------------------------------------------|
| estimation is | Earth shadow model: cylindric shadow |
| below) |--------------------------------------------------------|
| | Earth albedo: not applied |
| |--------------------------------------------------------|
| | Moon shadow model: umbra and penumbra |
| |--------------------------------------------------------|
| | Satellite attitude: nominal attitude |
| |--------------------------------------------------------|
| | Other forces: none applied |
|---------------------------------------------------------------------------|
| Relativistic | dynamical correction: applied according to IERS 2010, |
| effects | eq. 10.12, Lense-Thirring & |
| | geodesic precession neglected |
| |--------------------------------------------------------|
| | Gravitational time delay: applied according to |
| | IERS 2010, eq. 11.17 |
|---------------------------------------------------------------------------|
| Numerical | Integration algorithms developed at AIUB by Gerhard |
| Integration | Beutler (see references below). Representation of the |
| | the orbit by a polynomial of degree 10 for 1 hour. |
| |--------------------------------------------------------|
| | Integration step: 1 hour |
| |--------------------------------------------------------|
| | Starter procedure: no special starter procedure needed |
| |--------------------------------------------------------|
| | Arc length: 72 hours for long-arc solutions |
| | 24 hours for clean one-day solutions |
=============================================================================
=============================================================================
| ESTIMATED PARAMETERS (& APRIORI VALUES & CONSTRAINTS) |
|---------------------------------------------------------------------------|
| Adjustment | Weighted least-squares algorithms |
| method | |
|---------------------------------------------------------------------------|
| Data Span | Long-arc solutions include the data from three day, |
| | combined on normal equation level. |
| | Rapid/ultra-rapid: products are extracted from the |
| | last day of the triple. |
| | Final satellite orbits and troposphere parameters are |
| | extracted from the middle day |
| | |
| | Clean one-day solutions consider only the data from |
| | one single day. |
|---------------------------------------------------------------------------|
| Station | All station coordinates are adjusted with minimum |
| coordinates | constraints, see above. |
|---------------------------------------------------------------------------|
| Satellite clocks | Not applicable for double difference processing |
|---------------------------------------------------------------------------|
| Receiver clocks | Not applicable for double difference processing |
|---------------------------------------------------------------------------|
| Orbital | 6 Keplerian elements plus 5 solar radiation parameters |
| parameters | at start of arc; no a priori sigmas used. |
| | Estimated RPR parameters (see Beutler 1994): |
| | - Constants in D-, Y- and X-direction |
| | - Periodic terms in X-direction |
| | A priori orbits are from a previous reprocessing run |
| | or from the CODE rapid orbit solution. |
| | Pseudo-stochastic orbit parameters (small velocity |
| | changes), every 12 hours, constrained to: |
| | . 1.E-6 m/sec in radial |
| | . 1.E-5 m/sec in along-track |
| | . 1.E-8 m/sec in out-of-plane |
|---------------------------------------------------------------------------|
| Satellite | Not estimated |
| attitude | |
|---------------------------------------------------------------------------|
| Troposphere | Zenith delay: estimated for each station in intervals |
| | of 2 hours. Loose relative constraints of|
| | 1 m are applied. Piece-wise, linear |
| | parameterization, allowing for connection|
| | of the parameters at day boundaries. |
| |--------------------------------------------------------|
| | Zenith delay epochs: every two hours starting at |
| | midnight |
| |--------------------------------------------------------|
| | Mapping function: wet VMF1 |
| |--------------------------------------------------------|
| | Gradients: pairs of horizontal delay gradient |
| | parameters are estimated in N-S and E-W |
| | direction for each station in intervals of |
| | 24 hours. No a priori constraints are |
| | applied. Piece-wise, linear |
| | parameterization, allowing for connection of|
| | the parameters at day boundaries. |
| | Details about the gradient model can be |
| | found in Rothacher et al. (1997). |
| | Refined gradient model used, see Chen and |
| | Herring (1997). |
|---------------------------------------------------------------------------|
| Ionospheric | Not estimated in ionosphere-free analyses |
| correction | |
| | One scaling factor for 2nd and 3rd order terms and ray |
| | bending is setup to switch the components on or off |
| | on normal equation level. |
| | The products are generated with considering all three |
| | correction components. |
|---------------------------------------------------------------------------|
| Ambiguity | Ambiguities are resolved in a baseline-by-baseline |
| | mode performing the following steps: |
| | . Melbourne-Wuebbena approach (< 6000 km) |
| | . Quasi-Ionosphere-Free (QIF) approach (< 2000 km) |
| | (also for GLONASS, same frequencies) |
| | . Phase-based widelane/narrowlane method (< 200 km) |
| | (also for GLONASS, no restrictions) |
| | . Direct L1/L2 method, also for GLONASS (< 20 km) |
| | (also for GLONASS, no restrictions) |
| | GNSS-derived global ionosphere map information is used |
| | to support the code-less methods. |
|---------------------------------------------------------------------------|
| Earth Orient. | X- and Y-pole coordinates, and UT1-UTC are represented |
| Parameters (EOP) | each with piece-wise linear polynomials which are |
| | continuous in time. UT1-UTC is fixed to the a priori |
| | value at the beginning of the first day. No further |
| | a priori sigmas are used. |
| | |
| | All reported CODE EOP solutions do include a subdaily |
| | EOP model (see above). The estimates therefore |
| | correspond to daily averages on top of the introduced |
| | a priori model. |
| | |
| | Drifts in nutation (Dpsi, Deps) are solved for in a |
| | special 3-day solution. The corresponding nutation |
| | parameters generally set up are constrained to the |
| | IAU 2000R06 model for the CODE official solution. |
| | |
| | High-rate (1-hour) X-, Y- and UT1-UTC estimates are |
| | also generated in a special 3-day solution. |
|---------------------------------------------------------------------------|
| Other | Center of mass coordinates: |
| parameters | |
| | Center of mass, or geocenter coordinate parameters are |
| | commonly set up as part of each solution. The related |
| | parameters are usually heavily constrained to zero |
| | values. Additional computations on the normal equation |
| | level are made regularly in order to retrieve 1-day, |
| | 3-day, as well as weekly GNSS geocenter coordinates in |
| | the current ITRF. |
| | |
| | GNSS satellite phase center offsets and patterns: |
| | |
| | Corresponding parameters are commonly set up as part |
| | of each final solution for each individual GNSS |
| | satellite. The related parameters are usually heavily |
| | constrained to the corresponding nominal values (as |
| | defined by the IGS08 PCV model). Such GNSS PCV |
| | parameters are available for the ionosphere-free as |
| | well as the geometry-free linear combination. |
| | |
| | GPS/GLONASS bias parameter: |
| | |
| | An extra set of four parameters is set up for each |
| | GLONASS observing station to characterize: |
| | - one GLONASS-GPS receiver antenna offset vector |
| | (three components) and |
| | - one GLONASS-GPS ZPD troposphere bias. |
| | These biases are estimated on a weekly basis together |
| | with the station coordinates. |
| | |
| | APL scaling factors: see above |
| | |
=============================================================================
=============================================================================
| REFERENCES
|----------------------------------------------------------------------------
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