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What is GPS?
Originally developed by the Department of
Defense, the Global Positioning System (GPS),
was first launched in 1989. 24 NAVSTAR
satellites continuously broadcast time and
position messages, and a network of tracking
stations monitor and control the GPS satellites
in orbit. GPS works using triangulation. A GPS
receiver measures distances from (three or more)
satellites using the travel time of radio
signals and then determines its position by
calculations. Precise to within a few feet for
military uses and about 300 ft (90 m) for
non-military uses, the GPS is used for many
purposes, including navigation, surveying,
tracking vehicles, people & migrating animals,
and plotting the crop yields of small sections
of farmland. |
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