[IGSREPORT-478] EMR Analysis Report (week 712)

[Jan]

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IGS Electronic Report      8-SEP-1993 17:26:38       Message Number 478
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From: Jan Kouba 
Subj: EMR Analysis Report (week 712)
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					          (Aug 29 - Sep 04,93)

      Our analysis utilizes the JPL GIPSY/OASIS II (UNIX) software system 
and data from all (up to 7) Canadian stations augmented by up to 12, globally 
distributed, core stations (see Table 1 for the list of stations).  

      This effort is a part of a joint pilot project  called 
"Active Control System" and involves the Geodetic Survey Division  (GSD),
SMRSS; the Geophysics Division and Pacific Geoscience Centre of the
Geological Survey of Canada, all three institutions are part of the  
Department of Energy, Mines & Resources (EMR).

      Table 1 : Station Summary (also indicated are day no. for which a 
particular station is not included in the daily solution, either due to
being down or data being late). 
                               
   STATION            IGS code       MISSING DAY NO. 1993
Albert Head, CAN       ALBH              
Algonquin, CAN         ALGO*             
Fairbanks              FAIR*                              
Goldstone              GOLD*             
Hartebeesthoek         HART*              
Holberg,CAN            HOLB               
Kokee Park             KOKB             245 
Madrid                 MADR*             
McMurdo                MCMU*              
Pamatai                PAMA              241 to 247 
Penticton, CAN         DRAO              246 
Santiago               SANT*             
St. Johns, CAN         STJO             
Canbera                TIDB*             
Tromsoe                TROM*             246 
Wettzell               WETT*            
Yarragadee             YAR1*                    
Yellowknife, CAN       YELL*            
* indicates constrained stations, remaining are solved for (50m apriori sig.)

SOLUTION CHARACTERISTICS

Reference frame and orientation:
      Nominally ITRF91, at epoch 1992.5 is realized by constraining up to 12 
of the above stations at the IGS coordinates (see IGS message #90). 
Orientation is realized through the above coordinates and, once a week, 
the fixed DUT1 values from the current NEOS/IERS (Bull. A).

Constants and models: 
- no change, see the IGS mess. #101 for details.

Estimation strategies:
- no change, see the IGS mess. #101 for details - , except for the estimation
  of DUT1, stochastic orbit modeling, new weighting of L3,P3,
  see IGS mess. #130.

      ALGO was used as time reference.                           
      Aposteriori variance factors typically are between 0.5 and 1.0 (noise 
about 3mm and 200mm for phase and smoothed pseudorange observations, resp.). 

PRODUCTS GENERATED:
The following products are generated and uploaded into CDDIS @ NASA/GSFC
   EMR07120-6.EPH       GPS ephem. files for days 0-6, week # 712 in sp3 format 
   EMR07127.ERP        	pole x,y and DUT1 solutions for week # 712
   EMR07127.SUM        	name of this text summary file

REMARKS on EMR's products:
1. ALGO hydrogen maser used as a time reference. In the sp3 EPH file sat.
   epochs with no reference (e.g. ALGO not observing a satellite) have a value 
   of 99999. microseconds. 
   ALGO clock experienced erratic drift behavior on Aug31. 
   ALGO clock errors about 620ns (49228) and about 200ns (49230).
2. Starting with the week #709 we are including orbit sigma estimates in 
   the sp3 header format (lines 8 to 12), conforming to the sp3 convention 
   (see NOAA Technical Report NOS 133 NGS 46),  i.e. the binary exponent 
   of sigma in mm. For the orbits passing our quality analysis we are 
   assigning 9, which, in the sp3 convention, translates into 2**9=512mm 
   sigmas. For  errors larger than 2.5 we are assigning sigmas of 
   abs(error)/4 , again expressed by the binary exponent. In this way we 
   feel that problematic satellites indentification is easier and that 
   a range of errors formerly reported in our summary files can be recovered 
   as well.
3. AS was on for PRN17/24 on Sep. 03 (day246) and PRN17 on Sep. 04 (day247), 
   all observations for the affected satellites were downweighted, no DUT1 
   estimation on these days.
4. PRN02 data  was removed from the orbit processing and the eph file for 
   Aug 30 (day242) due to maintainance/orbit repositioning
5. No data for Sep 03 (246) for PRN03. The ephemeris in the eph file
   (emr07125.eph) is predicted and assigned accuracy code of 16 (66m).
6. PRN03 repositioned on Sep 04 (247) by about 1km.
-- 
Jan Kouba
Geodetic Survey of Canada
Ottawa, Ontario, Canada
Internet: kouba at geod.emr.ca