Instituto Brasileiro de Geografia e Estatística

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Geodesy

SIRGAS Combination Center – IBGE

Results

IBGwwwwS.SNX.gz – loosely-constrained covariance matrix of the weekly combination (position of all stations are a priori constrained with a 1 meter sigma).

ibgaaPwwww.snx.gz – IGS constrained covariance matrix of the weekly combination (IGS stations are constrained with a 0.0001m sigma).

ibgaaPwwww.crd – weekly coordinates of the IGS-referenced stations.

IBGwwwwS.SUM – combination report.

Weekly combination solutions area available on:
ftp://geoftp.ibge.gov.br/informacoes_sobre_posicionamento_geodesico/sirgas/combinacao/

The steps accomplished by the SIRGAS Combination Center – IBGE to determine the combined solutions are:

  1. Analysis of individual solutions;

  2. Elimination of individual solution constrainers;

  3. Individual solutions are constrained to the IGS network through fiducial stations:

    BOGT 41901M001
    GLPS 42005M002
    OHI2 66008M005
    BRAZ 41606M001
    GOLD 40405S031
    PALM 66005M002
    BRFT 41602M002
    GUAT 40901S001
    PARC 41716S001
    BRMU 42501S004
    ISPA 41703M007
    SCUB 40701M001
    CONZ 41719M002
    LPGS 41510M001
    UNSA 41514M001
    CRO1 43201M001
    MDO1 40442M012
    VESL 66009M001


  4. Combination of individual solutions referenced to IGS;

  5. Comparison of individual solutions combined in step 4. Stations with residues larger than 10mm in N-E and/or larger than 20mm in U not eliminated from the individual solution. Steps 3, 4 and 5 are iterative;

  6. Determination of the scale factor;

  7. Calculation of the weekly loosely-constrained solution (position of all stations are a priori constrained with a 1 meter sigma – IBGwwwwS.SNX) ;

  8. Calculation of the combined solution referenced to IGS network. This solution contains the coordinates used in practical applications.