[shaggylive]

Originally Posted by Dojey

Just to add a quick note on this though... GPS satellites are geo-synchronous, which means that they remain stationary with respect to a location on Earth. So essentially if you stay in one spot, you will always be using the same satellites.

no they move.
http://en.wikipedia.org/wiki/Global_...al_description

Orbiting at an altitude of approximately 20,200 kilometers (12,600 miles or 10,900 nautical miles; orbital radius of 26,600 km (16,500 mi or 14,400 NM)), each SV makes two complete orbits each sidereal day.[12] The ground track of each satellite therefore repeats each (sidereal) day. This was very helpful during development, since even with just four satellites, correct alignment means all four are visible from one spot for a few hours each day.