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Procedures for Tracking ILRS Station Changes

The ILRS is required to track critical station changes to aid analysts in identifying the source of changes in a station's data properties. These station changes, if undocumented, can lead to discontinuities and errors in our data and data products. If we do not properly record changes to the systems, our data will not be competitive with the other space geodesy techniques. In cases where changes could possibly affect data quality (or quantity), the data quarantine process is initiated.

Below are the station change procedures, some examples of changes to include, and the format of the new Station Change History Log.

Dates and Times for ALL of the fields in this form are in Universal Time (UT) frame.

Procedures for the stations

Updating the Station Change History Log is similar to the procedure for updating the Site Log:

  • Go to the EDC web site https://edc.dgfi.tum.de/
    • If you do not have an account, click on "Register" in the upper right corner to create one.
    • Once you have been notified by email that your registration has been approved, return to the EDC site and click on "Login" and enter your account name and password.
    • Click "My EDC".
    • Select "Station History Log" and proceed with the editing.
    • Note that more than one person may be registered to edit the site log for a particular station.
  • Edit page:
    Image of a sample station history log page
    • The page shows the log with the latest entry first.
    • From the menu bar above the log, select any of the following as needed:
      • "New Entry" - Add a new 'Change entry' to the top of the file. A form will display with all the required fields ready to be entered. This is the normal way to add information.
      • "Edit" - This mode allows editing one or more existing entries. A pencil and trashcan icon will appear at the end of each log line, allowing editing or deleting a line.
      • "Upload File" - Upload a file from your computer. It is better to edit the file online, so this option is generally not recommended.
      • "Download" - download the current file to your computer.
      • "Empty File" - delete all the entries from the log, and start with an empty log.
  • On the edit page, select your station from the pull-down menu, under the label "Please select station history log"; then press "elect Station History Log".
  • Changes that definitely have or are likely to have impact on the data quality (in the format below, Estimated Chance of Data impact Flag=2 or 3) should be transmitted within 24 hours of the change. Other changes should be reported within a week.

There are usually a great variety of changes and events recorded in the on-site station logs, some of which need to be included in the ILRS Station Change History Log. Some examples of changes that should be included are:

  • major changes and repairs involving the measurement chain; these would require quarantine, (see http://ilrs.gsfc.nasa.gov/network/site_procedures/station_qualification.html) e.g., repairing or installing a new type or model of:
    • timing system
    • laser
    • detector
    • optical elements
    • meteorological sensors

    as well as movement of the telescope, including any due to earthquakes (the occupancy sequence number in the Site Occupation Designator (SOD) may need to change – see http://ilrs.gsfc.nasa.gov/network/site_procedures/sod.html).

  • swapping new components for old (even if the same model number);
  • cable changes in critical subsystems that are in the signal path (timers and laser start, etc.);
  • re-positioning of critical optical elements;
  • re-coating, realigning optics, calibrating or adjusting critical equipment;
  • telescope servo and encoder changes;
  • meteorological sensor changes;
  • control system and data reduction software in the measurement chain;
  • major construction work, heavy equipment deployment, drilling or water pumping from underground, or similar activities (include stop date in an additional record); and
  • other changes that may influence the data; if there are doubts – include it.

Any questions regarding the configuration change procedure should be referred to the ILRS CB.

Station Change History Log file format

Each line describing a change contains the following:

  • PPPPSSMM – Site Occupation Designator (SOD)
  • YYYY -Year
  • DDD - Day of year
  • HH:MM - Time of Day (UTC) when change became active
  • F - Estimated Chance of Data impact Flag: 0=none; 1=maybe, but negligible; 2=slight influence possible; 3=YES, needs quarantine and verification by the ILRS.
  • xx[.xx[.xx]] - Subsystem: enter the subsystem number from the site log, e.g. “12.01” for pressure sensor. Use 99 for those subsystems not mentioned in the site log, e.g., computers, software, multiple sub-systems.
  • Text - Description of the change. This must be meaningful to the station personnel, so that more information can be made available to analysts if needed.
  • Each entry should be one line long, without wrap around.
  • New entries should be added to the beginning of the file.

A Station Change History Log header at the beginning of the file is composed of lines starting with %

% ILRS Station Change History Log for
% 7403  AREL  TLRS-3 @ Observatorio de Characato  <your station ID>
% Arequipa, Peru                                   <location>
%
% PPPPSSMM - Site Occupation Designator (SOD)
% YYYY - Year
% DDD - Day of Year
% HH:MM - Time of Day (UTC) when change becomes active 
% F - Estimated Chance of Data impact Flag: 0=none; 1=maybe, but negligible;
%    2=slight influence possible; 3=YES, needs quarantine and verification by the ILRS.
% xx[.xx[.xx]] - Subsystem:  enter the subsystem number from the site log,
%       e.g. "12.01" for pressure sensor.
%       Use 99 for those subsystems not mentioned in the site log, e.g. computers,
%       software, multiple sub-systems.
% Text - Description of the change. This must be meaningful to the station staff,
%    so that more information can be made available to analysts if needed
%
% Send this entire file to ILRS (edc.dgfi@tum.de) after each update
% 
% SOD       Year  DOY  UTC   F  sys  Text describing change