Satellite Acquisition - Garmin GPS II Plus Owner's Manual & Reference

To prevent accidental battery
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power loss, the GPS II
automatically shut off 10 min-
utes after the last keystroke if
the unit is not tracking at least
one satellite and has not
acquired a position fix.
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Satellite Acquisition

Because the GPS II
guidance, the receiver needs to have an unobstructed, clear view of the sky for best
performance. In a nutshell, the GPS receiver's view of the sky will generally deter-
mine how fast you get a position fix—or if you get a fix at all. GPSsignals are rela-
tively weak and do not travel through rocks, buildings, people, metal, or heavy tree
cover, so remember to keep a clear view of the sky at all times for best performance.
Once the GPS II
four to twelve satellites in view. The receiver will then continuously select the best
satellites in view to update your position. If some of the satellites in view get blocked
will
or "shaded," the receiver can simply use an alternate satellite to maintain the position
fix. Although a GPS receiver needs four satellites to provide a three-dimensional (3D)
fix, it can maintain a two-dimensional (2D) fix with only three satellites. A three-
dimensional fix means the unit knows its latitude, longitude, and altitude, while a
two-dimensional fix means the unit knows only its latitude and longitude.
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relies on satellite signals to provide you with navigation
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has calculated a position fix, you'll usually have anywhere from