my bad spelling of satellite, our globe is covered by 12 satellites of which a GPS system tries to find three or more to work out where you are.
so if you had a triangle of them like so in the sky
a
|>c
b
and you are x on the ground then you work out
abx
bcx
acx
and because abc are the same distance apart to you work out the angle and distance. (how I can't remember.)
hopefully someone else will jump in and give some code or more info on what I mean.
or you can read this which tells all but might not help.
http://en.wikipedia.org/wiki/Global_Positioning_System
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