Quote:
Originally Posted by shaggylive
does anybody know off hand wether the gps satelites are in stationary orbit like the tv sat's or do some or all "move"?
if they move, they still may disable the "public" frequence when over other parts of the works.
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From the Garmin website:
The 24 satellites that make up the GPS space segment are orbiting the earth about 12,000 miles above us. They are constantly moving, making two complete orbits in less than 24 hours. These satellites are travelling at speeds of roughly 7,000 miles an hour.
Selective Availability (SA) is an intentional degradation of the signal once imposed by the U.S. Department of Defense. SA was intended to prevent military adversaries from using the highly accurate GPS signals. The government turned off SA in May 2000, which significantly improved the accuracy of civilian GPS receivers.
http://www8.garmin.com/aboutGPS/