You're right, of course. I was thinking of the WAAS satellites.
Quote:
Originally Posted by mithodge
The sats are not geo-synchronous. That is why they need to have location data (ephemeris) uploaded every 4 hours.
"Each satellite in the GPS constellation orbits at an altitude of about 20,000 km from the ground, and has an orbital speed of about 14,000 km/hour (the orbital period is roughly 12 hours - contrary to popular belief, GPS satellites are not in geosynchronous or geostationary orbits). The satellite orbits are distributed so that at least 4 satellites are always visible from any point on the Earth at any given instant (with up to 12 visible at one time)." http://www.astronomy.ohio-state.edu/~pogge/Ast162/Unit5/gps.html |