Analysis Coordinator tips for using IGS products

The links below address some frequently asked questions regarding the generation and use of IGS products.

General IGS Product Information

• IGS adopts IGb08, an update to the IGS08 frame -- GPS week 1709
  
  • igs08.atx antenna calibration file is consistent with IGb08 frame (i.e., there is no igb08.atx)
  • important files at ftp://igs.org/pub/station/coord/:
    - IGb08.snx
    - IGb08_core.txt
    - IGS08-IGb08.dat; differences between the two frames
• IGS adopts IGS08 frame & igs08.atx antenna calibrations -- GPS week 1632
  
  • IGS08 frame & its core subnetwork described in IGS Mail 6354, by P. Rebischung et al. (07 Mar 2011)
  • igs08.atx antenna calibration changes described in IGS Mail 6355, by R. Schmid (07 Mar 2011); finalized in IGS Mail 6374 by R. Schmid (29 Mar 2011)
  • practical advice & tools for coping with framework changes described in IGS Mail 6356, by J. Griffiths et al. (07 Mar 2011)
  • use of IGS orbits for homogeneous long-term processing
  • adoption date was  17 April 2011 (GPS week 1632, day 0)
  • important files at ftp://igs.org/pub/station/coord/:
    - IGS08.snx
    - IGS08_core.txt
    - ITRF2008_to_IGS08.txt
    - new_calib/lat_models.txt
    - perl scripts to apply antenna- & latitude-dependent antenna corrections for consistency of igs05.atx results with igs08.atx
• Availability of homogeneously reprocessed products
  
  • see IGS Mail 6136 by G. Gendt & R. Ferland (26 Apr 2010)
  • note that the reference framework used was IGS05/igs05.atx
  • the available data range is from GPS week 0730 through 1459 for the reprocessed products plus consistent operational products from week 1460 through 1631
  • see IGS Mail 6445 by J. Ray & B. Garayt (04 Aug 2011) concerning finalization & archiving of product files
  • use of IGS orbits for homogeneous long-term processing
• "A Guide to Using IGS Products" by J. Kouba (May 2009)
• Status of IGS orbit products (IGS Mail 6053, 7 Jan 2010) 
    

GNSS Constellation Information 

• Understanding GPS -- Principles and Applications, E.D. Kaplan & C.J. Hegarty, eds., Artech House, Chapter 3, pp. 67-112, 2006)
• GLONASS-K satellite vehicle specifications
• Fig. 1 of S/V body dimensions
• Fig. 2 of S/V body dimensions
• Fig. 3 of S/V body dimensions
• Fig. 4 of solar panels
• model of GLONASS-K S/V
• photo of actual S/V body

File Formats 

• RINEX updates to handle phase shifts & other new features
  • see chapter 11 for new features in RINEX 2.12
  • see chapter 9 for new features in RINEX 3.01
• IGS file formats
• IGS ERP file format (version 2)
• IGS table of receiver and antenna equipment 
    

Terrestrial Reference Frame 

• Starting week 1709, the IGS reference frame is IGb08, and update to IGS08 (IGS Mail 6663, 24 Sep 2012)
• Starting week 1632, the IGS reference frame is IGS08 (IGS Mails 6354,  6355,6356, & 6374)
• From weeks 1400 through 1631 the IGS reference frame is IGS05 (IGS Mails 5447 & 5455)
• Change of IGS Reference Frame Coordinator (IGS Mail 6067, 28 Jan 2010;IGS Mail 6070, 02 Feb 2010)
• File of regularly updated station position/velocity discontinuities (IGS Mail 6110, 17 Mar 2010)
• Chronology of IGS reference frames 
    

SP3 Satellite Files 

• Use the SP3 orbit accuracy codes
• Handling IGS reference frame changes
• SP3 orbit interpolation algorithms: "A brief review of basic GPS orbit interpolation strategies" by M. Schenewerk (2003)
• C code for GPS orbit interpolation strategies by M. Schenewerk
• "Efficient interpolations to GPS orbits for precise wide area applications" by Y. Feng & Y. Zheng (2005)
• "Polynomial interpolation of GPS satellite coordinates" by M. Horemuz & J.V. Andersson (2006)
• Syntax of SP3 file comment lines
• Perl script to convert IGS orbit files from current SP3C format to obsolete SP3A (from G. Gendt & Th. Nischan); see IGS Mail 5000 
    

Antenna Information 

• Starting week 1709, the IGS reference frame was updated to IGb08 (IGS Mail 6663); the companion ATX file is igs08.atx. That is, igs08.atx is compatible with both IGS08 and IGb08
• Starting week 1632, the IGS antenna calibrations is igs08.atx (IGS Mails 6355& 6374)
• How to use IGS antenna phase center corrections (GPS World Tech Talk, 03 Feb 2010)
• General information on IGS antennna files
• Background on IGS antenna calibrations (IGS Mail 5189)
• IGS switch to absolute antenna calibrations & IGS05 frame starting week 1400 (IGS Mail 5438)
• Current antenna calibration file (igs05.atx)
• IGS conventions for SINEX antenna + radome information 
    

Inter-Signal Code Biases 

• Latest version (v6.5) of cc2noncc.f routine (from ESA group at European Space Operations Centre)
• Information on P1-C1 code biases (from CODE group at Astonomical Institute, University of Bern)
• File of historic P1-C1 code bias values (from ESA group at European Space Operations Centre) 
    

RINEX Conversion Software 

• Latest released set of pre-compiled builds of BKG Ntrip Client (BNC)
  • Set Edit Options for BNC - mandatory if 'Edit/Concatenate' is set on
    • Once the 'Edit/Concatenate' action is selected, you have to 'Set Edit Options'. BNC lets you specify the RINEX version, sampling interval, begin and end of file, operator, comment lines, and marker, antenna, receiver details. Note that sampling, begin/end and marker/antenna/receiver specification are only meaningful for RINEX Observation files.
    • When converting RINEX Version 2 to RINEX Version 3 Observation files, the tracking mode or channel information in the (last character out of the three characters) observation code is left blank if unknown.
    • When converting RINEX Version 3 to RINEX Version 2 Observation files:
      • C1P in RINEX Version 3 is mapped to P1 in RINEX Version 2
      • C2P in RINEX Version 3 is mapped to P2 in RINEX Version 2
      • If several observations in RINEX Version 3 come with the same observation type and same band/frequency but different tracking modes, BNC uses only the one provided first for creating RINEX Version 2 while ignoring others.
    • Optionally you may specify a comment line text to be added to the emerging new RINEX file header. Any introduction of a newline through '\n' in this enforces the beginning of a further comment line. Comment line(s) will be added to the header immediately after the 'PGM / RUN BY / DATE' record. Default is an empty option field, meaning that no additional comment line will be added to the RINEX header.
    • Specifying a 'RUN BY' string to be included in the emerging new RINEX file header is another option. Default is an empty option field meaning the operator's ID is automatically used as 'RUN BY' string.
    • If you specify a 'New' but no 'Old' marker/antenna/receiver name, the corresponding data field in the emerging new RINEX Observation file will be filled accordingly. If you in addition specify an 'Old' marker/antenna/receiver name, the corresponding data field in the emerging new RINEX Observation file will only be filled accordingly where 'Old' specifications match existing file contents.
  • BNC v2.8 help manual
  • Latest unreleased BNC builds (BncXX)
  
  
• cnvrnx3-rnx2-v3.f (from Oscar L. Colombo, GESTAR-USRA/NASA GSFC)
  • This program converts Rinex 3 files with mixed GPS and GLONASS data into Rinex 2 files with GPS only, or GPS+GLONASS data (other GNSS' data that might be in it is ignored).
  • The user chooses GPS only or GPS+GLONASS by entering the appropriate value of an argument in the program's command line.
  • In this version (3.11) some bugs have been fixed and minor changes made to improve its functioning. The combined name of the Rinex 3 file to be converted preceded (when necessary) by its path, can be up to 100 characters long. The translated Rinex 2 version is always created in the same working directory where this program is executed.
  • This program is written in Fortran, and can be compiled with the GNU's Gfortran, or with the old G77 (still around in many Linux machines), and also with any incarnation, past and present, of (the nowadays named) "Intel Fortran" for Windows, Linux, or Macs.
  • There are a number of running options, and the explanation at the beginning of the source code is probably enough to give a good idea of how to use it, and what one can get out of it. Also, by entering in the command line the name of the program without any arguments, one gets a listing on the screen that explains much the same things as the lines at the beginning of the source.
  • Depending on the compiler used, some lines in the code might have to be commented or uncommented. Those are the lines calling the subroutine that reads the arguments from the command line, and they are clearly marked in the code, so it is hard to miss them. These lines appear near de top of the executable code.
  
  

Recent Changes, Announcements, Notices, & Reports 

• Starting week 1709, the IGS reference frame is IGb08, and update to IGS08 (IGS Mail 6663, 24 Sep 2012)
• Update to IGS08.ATX, including JPSREGANT subtype calibrations & R743 (IGS Mail 6662, 24 Sep 2012)
• Switch to Finals products based on daily TRF integrations (IGS Mail 6613, 28 Jun 2012)
• New IGS Analysis Coordinator (IGS Mail 6512, 28 Dec 2011)
• Final report on IGS station clocks (IGS Mail 6511, 28 Dec 2011)
• IGS Analysis Center Workshop 2012, 23-27 July 2012, University of Warmia & Mazury, Olszty, Poland (IGS Mail 6444, 2 Aug 2011)
• Starting week 1632, the IGS reference frame is IGS08 (IGS Mail 6354) & the antenna calibrations are igs08.atx (IGS Mails 6355 & 6374)
• Availability of homogeneously reprocessed products (IGS Mail 6136 by G. Gendt & R. Ferland, 26 Apr 2010; IGS Mail 6445 by J. Ray & B. Garayt, 04 Aug 2011)
• IAG Commission 1 Symposium (REFAG2010), 4-8 October 2010, Marne la Vallee, France
• IGS Workshop 2010, 28 June-2 July 2010, Newcastle upon Tyne (IGS Mail 6075, 12 Feb 2010)
• Change of IGS Reference Frame Coordinator (IGS Mail 6067, 28 Jan 2010;IGS Mail 6070, 02 Feb 2010)
• Status of IGS orbit products (IGS Mail 6053, 7 Jan 2010)
• Proposed change to IGL sp3 file contents postponed (IGS Mail 6007, 29 Sep 2009)
• Calls for next-generation IGS combination system & for next Analysis Center Coordinator (IGS Mail 5984, 13 Aug 2009)
• IGS submission for ITRF2008 extended to add reprocessed years 1997 - 1999 (22 Jul 2009)
• IGU clock prediction exclusion policy modified (IGS Mail 5969, 14 Jul 2009)
• Exclusion of some IGU satellite clock predictions (IGS Mail 5965, 1 Jul 2009)
• C2 data versus P2 data (IGS Station Mail 3163, 29 Jun 2009)
• Precise Point Positioning Software Centre (IGS Mail 5949, 22 May 2009)
• IERS Workshop on EOP Combination & Prediction, 19-21 October 2009, Warsaw (IGS Mail 5943, 8 May 2009)
• IGS combined SINEX solution for reprocessed years 2000-2008 submitted to IERS for ITRF2008 (19 Feb 2009)
• Final 30s clock products modified (IGS Mail 5902, 19 Feb 2009)
• Status of IGS Ultra-rapid products (IGS Mail 5874, 2 Jan 2009)

Miscellaneous advice and information for ACs

• Sources for a priori EOP prediction information
• A clock prediction strategy
• Software for higher-order iono corrections
  • see package i2_soft_update_v1d.20100218.tgz
  • background & details given in IERS Conventions (2010), chapter 9.4