Thales Navigation 200 - Manual (Page 66)

Restarting the GPS
Restarting the GPS provides a means of giving the eXplorist information about its
approximate position, long time GPS receiver users will know this option as initializing. To
understand when you would use this option, a breif explanation of how the eXplorist works
will be helpful.
The GPS constellation consists of 24 satellites and three spares that orbit the earth, and at
any given time of the day a different collection of satellites will be overhead. To keep track
of what satellites are in view, the eXplorist has a built-in almanac that uses the present date
and time, along with its approximate position, to “look-up” what satellites should be in view.
Every time you turn your eXplorist off, it records in a special place in its memory, the last
position fix computed, and then when it is turned back on, it assumes that it is still in the
same approximate location and uses this last position fix when doing its “look-up” in the
almanac.
Now if you turn your eXplorist off and fly across the country, the next time you turn it back
on, it will think it is still at the location where it was turned off, and begin looking for the
satellites it thinks are overhead. If the satellites are not there, the eXplorist begins “polling”
the skies, trying to determine what satellites are in view. This process can take time and can
appear as if the GPS portion of the eXplorist is not working. Under normal conditions, the
eXplorist will still be able to compute your position but this can take longer then normal.
What
Restart GPS does is it gives you the ability to give the eXplorist its approximate
location, hence speeding up the time to acquire its first fix. Many eXplorist users will never
need to use the Restart the GPS option, but it is available should the need arise.
When to use
Restart GPS:
• When the eXplorist has been moved more then 500 miles (804.67 km) while turned off.
• When the eXplorist is sluggish and takes more then a few minutes to compute its first
position fix when turned on. (This really isn’t an option that you need to be concerned
about. The eXplorist has a built-in feature that when it has trouble computing its first
position fix, it automatically asks you to supply the approximate position.)
Restarting the GPS:
1. Press MENU.
2. Use the Arrow joystick to highlight
Preferences.
3. Press ENTER.
4. Use the Arrow joystick to highlight
Restart GPS.
5. Press ENTER.
Preferences 61
Preferences
Restart GPS
Map Units
Pwr Management
Personalize
Language
Clear Memory