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Positioning Application: Loading a GPS almanac has set the wrong satellite orbital reference time

  • PosApp
  • SimGEN
  • SimREPLAYplus
  • On Sunday August 22nd 1999 the GPS week number in the navigation message rolled over from 1023 to 0.
  • The WEEK values in YUMA format almanac files also rolled-over. Thus if a user downloads a YUMA almanac file the week number alone cannot determine the intended reference time of the orbital data.
  • PosApp will assume the current rollover value of 1, by default, but this may not necessarily be the required setting. 
  • You can manually edit the week rollover value when loading an almanac file via the GPS constellation file 'Load orbits from file' control.
  • You can also adjust the week rollover value to affect the scenario start time, using the "Start time" control panel.



Product : SimREPLAYplus,SimGEN,PosApp