How GPS Global Positioning System Works:

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How GPS (Global Positioning System) Works
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• Imagine you are somewhere in your town. You are
  TOTALLY lost. You ask someone, Where am I? They
  say, You are 5 miles from the fire station.
• This is nice, but it really doesnt help you. You
  could be anywhere on a circle 5 miles around the
  fire station!

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• You ask someone else where you are. They say,
  You are 7 miles from the library. If you
  combine this information with the fire station
  information, you have two circles that cross.
• You now know that you must be at one of these two
  points, if you are 5 miles from the fire station
  and 7 miles from the library.

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• A third person tells you that you are 4 miles
  from home.
• This circle will only cross the other circles at
  one point.
• You know exactly where you are. The only place
  all these circles cross is at the school!

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• GPS satellites work to the same way to find the
  location of a plane, ship, car, or a person lost
  in the city.

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• There are 24 GPS satellites orbiting Earth right
  now.
• The more of them that your GPS will lock onto the
  more accurately your position can be determined.

NASA/JPL
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• By collecting the information from several
  satellites, a GPS unit can determine your exact
  location on Earth.

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Garmin GPS 72
Power
Page
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What to look for and record
Elevation
Satellites
Latitude
Longitude