[IGSMAIL-5440]: IGS Switch to new antenna model - a few remarks

[gend at gfz-potsdam.de]

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IGS Electronic Mail      15 Oct 23:50:41 PDT 2006      Message Number 5440
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Author: Gerd Gendt

Dear colleagues,

I would like to clarify the items raised for the new antenna model.

Precise Point Positioning with IGS Products:
Of course, to get the highest quality station positions with PPP the
compatibel ANTEX file has to be used.
Nevertheless, we have done some tests to see what the station position errors
would be if the user has an old software and can only implement from the
igs05.atx the satellite offsets as well as the receiver offsets and elevation
dependent PCVs (i.e. ignoring the satellite antenna nadir dependence and the
azimuthal dependence for the receivers). 
In this case one gets a scale error of about 0.8 ppb and translation errors
of smaller than 0.5 mm. The position errors are site dependent (antenna
depedent) and amount to +- 5 mm in the heights (in addition th the scale) and
sub-mm in N and E. (see attached paper, which will soon be published in the
proceedings of the IGS 2006 Workshop in Darmstadt).


ANTEX file name in SP3:
In the SP3 file there is not enough room to code all the necessary
information one would like to see there.
Therefore it was decided to shorten the name of the ANTEX file to its
base name part, i.e.
  instead of igs05_1390   only   igs05 (base name)
  (the general name is igsYY_WWWW.atx;       YY year, WWWW - GSPWeek).
  
For updating one realization, e.g. igs05, the corresponding GPSWeek is
added to the filename. The basic rule is, however, that existing
calibrations in the ANTEX realization must be fixed and can never be
changed (see IGSMAIL-5272,19 Dec 2005). 
By this rule, even for older products, always the latest ANTEX file can be
used, i.e. one has not to identify the ANTEX for a corresponding date.

Changes are only allowed with a new realization, e.g. igs07. Those new
realizations are only planned with a new full reprocessing of all
historical data with the provision of a complete new set of products.
This way the user will again have compatible products for the whole
history.

To ease the retrieval of the latest file the IGS will consider to set a
link from igs05.atx to the latest realization.
      

Best regards
Gerd Gendt


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*                         Gerd Gendt                                         *
*  _/_/_/  _/_/_/_/_/_/   GeoForschungsZentrum                               *
* _/       _/       _/    Department Geodesy and Remote Sensing              *
* _/ _/_/  _/_/    _/     Telegrafenberg A17                                 *
* _/    _/ _/     _/      D-14473 Potsdam ,  GERMANY                         *
*  _/_/_/  _/    _/_/_/   Phone : ++49 331 288 1114   Fax :++49 331 288 1759 *
*                         E-Mail: gendt at gfz-potsdam.de                       *
* IGS GFZ AC         :    AFTP://ftp.gfz-potsdam.de/pub/igsprod              *
*                         http://www.gfz-potsdam.de/igs                      *
* IGS Analysis Coord.:    AFTP://ftp.gfz-potsdam.de/pub/igsacc               *
*                         http://www.gfz-potsdam.de/igsacc                   *
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