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GPS Facts
Question | Answer |
---|---|
How many GPS satellites are there? | Minimum of 24 plus some spares. Currently there are 28 operational satellites. The number varies - see http://tycho.usno.navy.mil/gpscurr.html for up-to-date status. |
What is the orbital distance of the satellites? | 20,200 km (10,900 miles) |
How many satellites are required to allow 3 dimensional positioning? | At least 4. The system is designed so that there are always at least 4 satellites visible at every location on earth. |
What are the 3 dimensions for a position? | Latitude, Longitude, and Altitude. |
How long does each satellite take to complete one orbit? | 12 hours |
When was the first GPS satellite launched? | 1978 |