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Axion 3D Atlas
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gps.txt
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1998-01-23
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{bigtext=20,85,"GPS"}
{4}(Global Positioning System){4}
{4}To see the orbits of the GPS satellites, click {s,"08,1",here}{4}!
{4}Originally designated the NAVSTAR (Navigation System with Timing And Ranging)
Global Positioning System, GPS was developed by the US Department of Defense to
provide all-weather round-the-clock navigation capabilities for military ground,
sea, and air forces. Since its implementation, GPS has also become an integral
asset in numerous civilian applications and industries around the globe, including
recreational uses (e.g. boating, aircraft, hiking), corporate vehicle fleet
tracking, and surveying.
GPS employs 24 spacecraft in 20,200 km circular orbits inclined at 55 degrees.
These spacecraft are placed in 6 orbit planes with four operational satellites
in each plane. All launches have been successful except for one launch failure
in 1981. The full 24-satellite constellation was completed on March 9, 1994.
The GPS satellites are continuously broadcasting highly accurate time signals.
The receiver can determine your position on or above the earth's surface by
measuring the time difference of when it receives the same signal from different
satellites. With signals from 3 satellites, the receiver can determine latitude and
longitude. With 4 satellites or more, visible from your location, the receiver can
determine altitude as well. The constellation of GPS satellites is designed so
that for any point on earth at any time, there should be at least 3 satellites
visible.