From NRCan/GSDivision Wed Apr 5 07:42:31 1995 From: NRCan/GSDivision (EMR Analysis Centre) Date: Wed, 5 Apr 1995 7:42:31 PDT Subject: [IGSMAIL-0928] EMR Processing Summary (1995) Message-ID: ****************************************************************************** IGS Electronic Mail Wed Apr 5 7:42:31 PDT 1995 Message Number 0928 ****************************************************************************** Author: NRCan/GSDivision (EMR Analysis Centre) Subject: EMR Processing Summary (1995) Dear IGS collegues, Below is our updated Processing Summary (A.C. Questionnaire) submitted to IGS CB. Greetings, EMR AC team ----------------- INTERNATIONAL GPS SERVICE FOR GEODYNAMICS Analysis Centre Questionnaire ============================================================================= ANALYSIS CENTRE | EMR, Geodetic Survey Division, Natural Resources Canada | (NRCan), (Formerly EMR Canada) | 615 Booth Street, Ottawa, Canada, K1A 0E9 ----------------------------------------------------------------------------- CONTACT PERSON(S) | Pierre Tetreault (pierre at geod.emr.ca), ph.(613) 9922218 | Jan Kouba (kouba at geod.emr.ca) , ph.(613) 9922678 ----------------------------------------------------------------------------- SOFTWARE USED | GIPSY/OASIS II (April 92 version), developed by JPL ----------------------------------------------------------------------------- IGS PRODUCTS | EMR0www0-6.sp3 GPS ephemeris/clock files in 7 daily files GENERATED FOR | at 15 min intervals in sp3 format, GPS WEEK 'www' | including orb. acc. codes, 2* for. sigmas | assigned nominally, adjusted as needed when | indicated by orbit corrections | EMR0www7.erp ERP (pole, UT1-UTC, LOD) solutions | EMR0www7.sum Processing summary. Includes sat./station | daily statistics (phase/pseudorage rms), | daily station clock solutions. ----------------------------------------------------------------------------- PREPARATION DATE | March 31, 1995 ============================================================================= ----------------------------------------------------------------------------- | MEASUREMENT MODELS | |---------------------------------------------------------------------------| | Preprocessing | single station type, using L1-L2 phase and pseudorange | | | data, editing most cycle slips, computes smoothed | | | pseudoranges at requested intervals (7.5min), | | | introduces and initilizes real phase ambiguities | |---------------------------------------------------------------------------| | Basic observable | carrier phase and smoothed pseudo-range | | |--------------------------------------------------------| | | elevation angle cutoff : 15 degrees | | | sampling rate : 7.5 minutes | | | weighting : exponentional, station/satell.| | | specific. | | | Rejection criteria : 5 (aposteriori) sigmas | |---------------------------------------------------------------------------| | Modelled | undifferenced, corrected for ionosphere (L3, P3), | | observable | CA pseudoranges corrected for CA-P1 biases whenever | | | applicable | |---------------------------------------------------------------------------| | RHC Polar. phase | applied (Wu et al., 1993) | | rotation corr. | | |---------------------------------------------------------------------------| | Ground antenna | not applied | | phase centre cal.| | |---------------------------------------------------------------------------| | Troposphere | Zenith delay: treated as a random walk process | | |--------------------------------------------------------| | | Mapping function: Lanyi mapping function | | |--------------------------------------------------------| | | Met. data input : Global constant values | |---------------------------------------------------------------------------| | Ionosphere | not modelled (ionospheric effects accounted for by | | | dual frequency observations, see above) | |---------------------------------------------------------------------------| | Plate motions | 13 ITRF93 station velocities fixed (see IGSMAIL#819) | |---------------------------------------------------------------------------| | Tidal | Solid earth tidal displacement: applied (IERS, 1992) | | displacement | Correction applied to remove | | | permanent tide : not applied | | | Nominal h2 and l2 values : 0.609 , 0.0852 | | | dh periodic change (IERS,1992, | | | eqn. (7), p. 57) : applied (IERS, 1992) | | |--------------------------------------------------------| | | Pole tide : applied (IERS, 1992) | | |--------------------------------------------------------| | | Ocean loading : Pagiatakis (1982) model| |---------------------------------------------------------------------------| | Atmospheric load.| not applied | |---------------------------------------------------------------------------| | Satellite center | Block I x,y & z: (0.210, 0, 0.854m) | | of mass |--------------------------------------------------------| | correction | Block II/IIA x,y & z :(0.279, 0, 1.0229 m) | |---------------------------------------------------------------------------| | Satellite phase | not applied | | centre calibrat. | | |---------------------------------------------------------------------------| | Relativity | applied (only periodic term) | ----------------------------------------------------------------------------- ----------------------------------------------------------------------------- | ORBIT MODELS | |---------------------------------------------------------------------------| | Geopotential | GEM T3 + C21+S21 model up to degree and order 8 | | |--------------------------------------------------------| | | GM=398600.4415 km**3/sec**2 | | |--------------------------------------------------------| | | AE = 6378.137 km | |---------------------------------------------------------------------------| | Third-body | Sun, Moon and planets regarded as point masses | | |--------------------------------------------------------| | | ephemeris: JPL DE200 | | |--------------------------------------------------------| | | GMsun = 132712439935.4842 km**3/sec**2 | | |--------------------------------------------------------| | | GMmoon = 4902.7991 km**3/sec**2 | |---------------------------------------------------------------------------| | Solar radiation | direct radiation: ROCK4 and ROCK42T models for | | pressure | Block I and II satellites, resp. | | | area, specularities and reflectivity used: see | | | Tables 1,2, (Fliegel and Gallini, 1992, JGR(97)B1,p562)| | | | | | satellite masses used: PRN 12 519.8kg | | | PRN 01 880.0kg PRN 21-22 883.9 | | | 02 878.2 23 972.9 | | | 14 887.4 24-31 880.0 | | | 15 885.9 04-06 972.9 | | | 16-19 883.2 07 883.9 | | | 20 887.4 09 972.9 | | |--------------------------------------------------------| | | x,z, scale and y- radiation biases: taken into account | | |--------------------------------------------------------| | | Earth shadow model includes: penumbra and atmospheric | | | refraction/attenuation effects | | |--------------------------------------------------------| | | reflection radiation: not applied | | |--------------------------------------------------------| | | new GPS satellite attitude model: applied(IGSMAIL#591) | | | geometrical effects : applied | | | orbit dynamic (integration) eff.: not applied | | | yaw rates(estimated/nominal) : NOMINAL | |---------------------------------------------------------------------------| | Tidal forces | solid earth tides: frequency independent Love's | | | number K2= 0.300 | | |--------------------------------------------------------| | | Ocean tides: UT CSR model from Schwiderski | |---------------------------------------------------------------------------| |---------------------------------------------------------------------------| | Numerical | variable (high) order Adams predictor-corrector | | integration | with direct integration of second-order equations | | |--------------------------------------------------------| | | integration step : variable (typically < 1000s) | | |--------------------------------------------------------| | | starter procedure: Runge-Kutta | | |--------------------------------------------------------| | | arc length : 24 hours | ----------------------------------------------------------------------------- ----------------------------------------------------------------------------- | ESTIMATED PARAMETERS (APRIORI VALUES & SIGMAS) | |---------------------------------------------------------------------------| | Adjustment | square-root information filter (SRIF) [Bierman, 1977] | |---------------------------------------------------------------------------| | Station | 13 stations constrained to the ITRF93 positions (using | | coordinates | ITF93 sigmas) as given in IGSMAIL#819, the remaining | | | stations estimated (50m apriori sigmas). The ITRF93 | | | velocities are used for daily coordinates updates. | | |--------------------------------------------------------| | | In POSTPROCESSING and station combination, | | | Apriori station constraints are rigorously removed | | | for input into combined station solutions (adding | | | the reduced normal matrices);including vel. & EOP | |---------------------------------------------------------------------------| | Satellite clock | modelled as white noise process and solved for at each | | bias | epoch. ( 1ms appriori sigmas, apriori values from | | | broadcast message). Thus each epoch solution is | | | independent and based on both phase and pseudorange | | | observations. WARNING: no L1-L2 satellite calibration | | | applied, so the satellite clocks include the L1-L2 | | | calibration delays | |---------------------------------------------------------------------------| | Receiver clock | a white noise process (with large 1 s apriori sigmas, | | bias | apriori values from preprocessing). One Hydrogen Maser | | | clock fixed and used as a time reference, usually ALGO.| | | Thus each epoch solution is | | | independent and based on both phase and pseudorange | | | observations. WARNING: no P1-P2 receiver calibration | | | applied, so the receiver clocks include the P2-P1 cal. | | | delays, whenever applicable (i.e. Rogues SNR8-800) | |---------------------------------------------------------------------------| | Orbital | initial position and velocity, solar radiaton pressure | | parameters | scales in x, z and y-bias considered | | | constant through the orbital arc. Orbit states modelled| | | as a random walk process between adjacent 24h orbit | | | arcs.Apriori orbits, extrapolated from previous arc are| | | assigned the following stochastic sigmas | | | (for convenience Keplerian elements are used, then | | | transformed into the x,y,z frame of reference used for | | | processing): | | | semi-major axis(a) : .10m/sqrt(day) | | | eccentricity (e) : .12m/sqrt(day) | | | inclin., node(i,RA): .06m/sqrt(day) | | | perigee, M.A (p,MA): .16m/sqrt(day) | | | velocity (DX,DY,DZ): .00005m/s/sqrt(day) non eclipsing | | | .0001m/s/sqrt(day) eclipsing | | | Gx scale : .05 (white noise) | | | Gy scale : .02 (white noise) | | | Gy bias : .1d-09 m/s**2 ( " " ) | |---------------------------------------------------------------------------| | Troposphere | estimated as a random walk (within a 24h) with about | | | 0.01m/sqrt(hr) sigma. All stations are assigned | | | the same apriori values of 2.0m with 0.4m apriori | | | sigmas to initiate the random walk process. | |---------------------------------------------------------------------------| | Ionospheric | not estimated, L1 & L2 used for the 1st order | | correction | corrections | |---------------------------------------------------------------------------| | Ambiguitiies | real ,estimated as needed (from preprocessing), with | | | apriori values from pseudorange observation preprocess.| | | apriori sigmas 3.0D08m | |---------------------------------------------------------------------------| | EOP | x & y pole, UT1-UTC and LOD. Current IERS Bulletin A, | | | (updated every two weeks only) and used as apriori. | | | Constant during a 24h period, solutions refer to | | | 12:00h UT. | | | Apriori sigmas used: | | | x,y pole x, y : 100 mas | | | UT1-UTC : 7 ms | | | LOD : 300 ms/day. | | | | | | Note: In POSTPROCESSING the EOP and/or station apriori | | | sigmas can be rigorously removed or changed | |---------------------------------------------------------------------------| | Other | C1-P1 Pseudorange biases periodically checked and | | parameters | updated as necessary from postfit pseudorange residuals| ----------------------------------------------------------------------------- ----------------------------------------------------------------------------- | REFERENCE FRAMES | |---------------------------------------------------------------------------| | Inertial | Geocentric; mean equator and equinox of 2000 Jan 1.5 | | | (J2000.0) | |---------------------------------------------------------------------------| | Terrestrial | ITRF93 reference frame realized through the set of 13 | | | station coordinates and velocities as given in IGSMAIL#| | | 819 as well as the antenna offsets for the above | | | stations as given in /igscb/station/tie/localtie.tab | | | which is available from IGS CB (sideshow.jpl.nasa.gov) | |---------------------------------------------------------------------------| | Interconnection | Precession: IAU 1976 Precession Theory | | |--------------------------------------------------------| | | Nutation : IAU 1980 Nutation Theory + CP corr.(Bull.A)| | |--------------------------------------------------------| | | Relationship between UT1 and GMST: Aoki et al. (1982) | | |--------------------------------------------------------| | | EOP interpolated from IERS Bulletin A (updated every | | | two weeks. Celestial Pole (CP) corrections used) | | |--------------------------------------------------------| | | Tidal variations in UT1: periods > 5.8days modelled | | | but not removed, UT1-UTC solutions | ----------------------------------------------------------------------------- References: Aoki, S., Guinot, B., Kaplan, G.H., Kinoshita, H., McCarthy, D.D., Seidelman, P.K. (1982). "The New Definition of Universal Time", Astron. Astrophys., 105, pp. 359-361. Bierman, G.J. (1977). "Factorization methods for discrete sequential estimation, Academic Press, San Diego, Calif. IERS (1992) Standards, IERS Technical Note 13, Observatoire de Paris, (edited by McCarthy, D.) Lichten, S. M. (1990). "Estimation and Filtering for high-precision GPS positioning applications." Manuscripta Geodeatica, Vol. 15, pp. 159-176. Tralli, D. M. and S. M. Lichten (1990). "Stochastic estimation of tropospheric path delays in global positioning system geodetic measurements." Bulletin Geodesique, Vol. 64, No. 2. pp. 127-159. Sovers and Border (1990). Observation model and parameter partials for the JPL geodetic modeling software "GPSOMC". JPL Publication 87-21, Rev. 2, JPL, Pasadena, CA, USA. Pagiatakis, S.D.(1982)." Ocean loading, body tides and polar motion effects on very long baseline interferometry". UNB Technical rep. No. 2, Dept. of Surv. Engineering, Univ. of New Brunswick, Fredericton, N.B. Kouba,J., P. Tetreault, R. Ferland and F. Lahaye (1993)."IGS data processing at the EMR Master Control System Centre", Proceedings of the 1993 IGS Workshop, held at Univ. of Berne, Switzerland, March 1993, pp.123-132. Wu J.,T. et al., (1993). "Effects of Antenna Orientation on GPS Phase, Manuscripta Geodetica (1993)", 18, pp. 91-98. -- [Mailed From: Jan Kouba ]