[IGSMAIL-0656] GFZ ACquestionnaire
G.Gendt
G.Gendt
Thu Jun 30 23:00:48 PDT 1994
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IGS Electronic Mail Thu Jun 30 23:00:48 PDT 1994 Message Number 0656
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Author: G.Gendt, G. Dick
Subject: GFZ ACquestionnaire
Subject: GFZ AC Questionnaire
Dear Colleagues,
The following AC questionnaire was submitted to IGS CB.
Best regards
Gerd Gendt
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GeoForschungsZentrum Potsdam
INTERNATIONAL GPS SERVICE FOR GEODYNAMICS
Analysis Centre Questionnaire
==============================================================================
| ANALYSIS CENTRE | GFZ, GeoForschungsZentrum Potsdam |
| | Dept. 1 |
| | D-14473 Potsdam |
| | |
|------------------------------------------------------------------------------|
| CONTACT PERSON(S) | Christoph Reigber |
| | (reigber at gfz-potsdam.de),ph.(0331) 2881100 |
| | Gerd Gendt (gend at gfz-potsdam.de), ph.(0331) 2881114 |
| | Galina Dick (dick at gfz-potsdam.de), ph.(0331) 2881185 |
|------------------------------------------------------------------------------|
| SOFTWARE USED | EPOS.P.V2 developed at GFZ |
| -----------------------------------------------------------------------------|
| IGS PRODUCTS | GFZwwww0-6.sp3 GPS ephemeris/clock files in 7 daily files|
| GENERATED FOR | at 15 min intervals in sp3 format, |
| GPS WEEK 'wwww' | including accuracy codes, which are assigned|
| | 25 cm nominally, and adjusted upward when |
| | indicated by orbit corrections |
| | GFZwwww7.erp ERP (pole, LOD) solutions |
| | GFZwwww7.sum Processing summary. |
|------------------------------------------------------------------------------|
| PREPARATION DATE | June 29, 1994 |
==============================================================================
---------------------------------------------------------------------------
| MEASUREMENT MODELS |
|---------------------------------------------------------------------------|
| Preprocessing | no preprocessing performed |
|---------------------------------------------------------------------------|
| Basic Observable | carrier phases ( pseudo-ranges normally used for |
| | ambiguity-fixing only) |
| |--------------------------------------------------------|
| | elevation angle cutoff : 20 degrees |
| | sampling rate : 6 minutes |
| | no weighting |
|---------------------------------------------------------------------------|
| Modelled | undifferenced, corrected for ionosphere (L3, P3), |
| observable | CA pseudoranges not corrected for CA-P1 biases |
|---------------------------------------------------------------------------|
| RHC phase | not applied |
| rotation corr. | |
|---------------------------------------------------------------------------|
| Ground antenna | not applied |
| phase centre cal.| |
|---------------------------------------------------------------------------|
| Troposphere | Zenith delay: adjusted in 4 hour- intervals |
| |--------------------------------------------------------|
| | Mapping function: Saastamoinen |
|---------------------------------------------------------------------------|
| Ionosphere | not modelled (ionospheric effects accounted for by |
| | dual frequency observations, see above) |
|---------------------------------------------------------------------------|
| Plate motions | ITRF 92 station velocities fixed (see IGSMAIL#421) |
|---------------------------------------------------------------------------|
| Tidal | Solid earth tidal displacement: Wahr model |
| displacements |--------------------------------------------------------|
| | Pole tide: applied |
| |--------------------------------------------------------|
| | Ocean loading: Scherneck (1991) model |
|---------------------------------------------------------------------------|
| Atmospheric load.| not applied |
|---------------------------------------------------------------------------|
| Satellite center | Block I x,y & z : (0.2100 m , 0 , 0.8540 m) |
| of mass |--------------------------------------------------------|
| correction | Block II/IIA x,y & z : (0.2794 m , 0 , 1.0229 m) |
|---------------------------------------------------------------------------|
| Satellite phase | not applied |
| centre calibrat. | |
|---------------------------------------------------------------------------|
| Satellite clock | relativistic corrections applied |
| corrections | |
---------------------------------------------------------------------------
---------------------------------------------------------------------------
| ORBIT MODELS |
|---------------------------------------------------------------------------|
| Geopotential | JGM2 degree and order 8 |
| | (C21, S21 modelled acc. to polar motion ) |
| |--------------------------------------------------------|
| | GM=398600.4418 km**3/sec**2 |
| |--------------------------------------------------------|
| | AE = 6378.137 km |
|---------------------------------------------------------------------------|
| Third-body | Sun, Moon , Venus, Jupiter (regarded as point masses) |
| |--------------------------------------------------------|
| | ephemeris: JPL DE200 |
| |--------------------------------------------------------|
| | Earth-Moon mass ratio = 81.300587 |
| |--------------------------------------------------------|
| | Sun-Earth mass ratio = 332946.045 |
|---------------------------------------------------------------------------|
| Solar radiation | direct radiation: T10 and T20 models for |
| pressure | Block I and II satellites, resp. |
| | |
| | masses: |
| | 972.90 kg for PRN 1 4 5 6 7 9 22-32 |
| | 878.15 kg for PRN 2 |
| | 521.81 kg for PRN 3 |
| | 440.89 kg for PRN 8 |
| | 522.16 kg for PRN 11 |
| | 519.82 kg for PRN 12 |
| | 520.42 kg for PRN 13 |
| | 887.36 kg for PRN 14 |
| | 885.90 kg for PRN 15 |
| | 883.23 kg for PRN 16 17 18 19 |
| | 887.36 kg for PRN 20 |
| | 883.90 kg for PRN 21 |
| |--------------------------------------------------------|
| | direct-scale and y-radiation biases: taken into account|
| |--------------------------------------------------------|
| | Earth shadow model includes: penumbra |
| |--------------------------------------------------------|
| | new GPS satellite attitude model: NOT APPLIED |
|---------------------------------------------------------------------------|
| Tidal forces | solid earth tides: frequency dependent Love's |
| | numbers by Wahr-model ( nominal k2= 0.300 ) |
| |--------------------------------------------------------|
| | Ocean tides: Schwiderski-model |
|---------------------------------------------------------------------------|
| Relativity | not applied |
|---------------------------------------------------------------------------|
| Numerical | single step integrator from Everhart |
| integration | with direct integration of second-order equations |
| of orbit |--------------------------------------------------------|
| | integration step: variable, automatically controlled |
| |--------------------------------------------------------|
| | arc length: 32 hours |
|---------------------------------------------------------------------------|
| Numerical | multistep step integrator Stoermar-Cowell |
| integration | with direct integration of second-order equations |
| of var. equations|--------------------------------------------------------|
| | integration step: fixed |
| |--------------------------------------------------------|
| | start procedure: Cowell-Kulikov |
---------------------------------------------------------------------------
---------------------------------------------------------------------------
| ESTIMATED PARAMETERS (APRIORI VALUES & SIGMAS) |
|---------------------------------------------------------------------------|
| Adjustment | Helmert blocking method |
|---------------------------------------------------------------------------|
| Station | 13 stations constrained to the ITRF92 positions (using |
| coordinates | ITF92 sigmas) as given in IGSMAIL#430, the remaining |
| | stations estimated. The ITRF92 velocities are used |
| | for daily coordinates updates. |
|---------------------------------------------------------------------------|
| Satellite clock | solved for at each epoch (white noise process) |
| | |
|---------------------------------------------------------------------------|
| Receiver clock | solved for at each epoch (white noise process) |
| | One clock fixed and used as a time reference, |
| | usually ALGO. |
|---------------------------------------------------------------------------|
| Orbital | initial position and velocity, solar radiation pressure|
| parameters | scale and y-bias |
| | constant through the orbital arc. |
|---------------------------------------------------------------------------|
| Troposphere | estimated in steps of 4 hours |
|---------------------------------------------------------------------------|
| Ionospheric | not estimated |
| correction | |
|---------------------------------------------------------------------------|
| Ambiguity | real value |
| | apriori values from pseudorange observation |
| | constrained to about 50 meter |
|---------------------------------------------------------------------------|
| ERP | x & y pole and LOD. |
---------------------------------------------------------------------------
---------------------------------------------------------------------------
| REFERENCE FRAMES |
|---------------------------------------------------------------------------|
| Inertial | Geocentric; mean equator and equinox of 2000 Jan 1.5 |
| | (J2000.0) |
|---------------------------------------------------------------------------|
| Terrestrial | ITRF92 reference frame realized through the set of 13 |
| | station coordinates and velocities as given in IGSMAIL#|
| | 430 as well as the antenna offsets for the above |
| | stations given in /igscb/station/tie/localtie.tab |
| | available from IGS CB (sideshow.jpl.nasa.gov) |
|---------------------------------------------------------------------------|
| Interconnection | Precession: IAU 1976 Precession Theory |
| |--------------------------------------------------------|
| | Nutation : IAU 1980 Nutation Theory |
| |--------------------------------------------------------|
| | Tidal variations in UT1: applied for periods <= 32 days|
---------------------------------------------------------------------------
References:
Scherneck, H.-G., 1991. A parametrized solid earth tide model and ocean
tide loading effects for global geodetic baseline measurements,
Geophys. J. Int., 106, 677-694.
--
********************************************************************************
* Gerd Gendt *
* GeoForschungsZentrum *
* Aufgabenbereich 1 Tel.: (0331) 288 1114 *
* Telegrafenberg A17 Fax.: (0331) 288 1111 *
* D-14473 Potsdam e-Mail: gend at gfz-potsdam.de *
* GERMANY *
********************************************************************************
[Mailed From: gend at gfz-potsdam.de (Gerd Gendt)]
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