Garmin GPS II Plus - Manual (Page 8)

2
Satellite Acquisition
Satellite Acquisition
Because the GPS II + relies on satellite signals to provide you with navigation
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. GPS signals 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 + has calculated a position fix, you’ll usually have anywhere from
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
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.
To prevent accidental battery
power loss, the GPS II
+ will
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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