Garmin: What is GPS? - The Diigo Meta page

• 16 Aug 06
  

  Kalyani

  fyp

  • lmanac data, which is constantly transmitted by each satellite,   contains important information about the status of the satellite   (healthy or unhealthy), current date and time. This part of the   signal is essential for determining a position.
  • Ephemeris data tells the GPS receiver where each GPS satellite   should be at any time throughout the day. Each satellite transmits   ephemeris data showing the orbital information for that satellite   and for every other satellite in the system.
  • a pseudorandom code, ephemeris data and almanac data. The pseudorandom   code is simply an I.D. code that identifies which satellite is   transmitting information.
  • GPS satellites transmit two low power radio signals, designated   L1 and L2. Civilian GPS uses the L1 frequency of 1575.42 MHz in   the UHF band. The signals travel by line of sight, meaning they   will pass through clouds, glass and plastic but will not go through   most solid objects such as buildings and mountains.
  • WAAS   (Wide Area Augmentation System)
  • A GPS receiver must be locked on to the signal of at least three   satellites to calculate a 2D position (latitude and longitude)   and track movement. With four or more satellites in view, the   receiver can determine the user's 3D position (latitude, longitude   and altitude). Once the user's position has been determined, the   GPS unit can calculate other information, such as speed, bearing,   track, trip distance, distance to destination, sunrise and sunset   time and more.

  • How it works

     

    GPS satellites circle the earth twice a day in a very precise   orbit and transmit signal information to earth. GPS receivers   take this information and use triangulation to calculate the user's   exact location. Essentially, the GPS receiver compares the time   a signal was transmitted by a satellite with the time it was received.   The time difference tells the GPS receiver how far away the satellite   is. Now, with distance measurements from a few more satellites,   the receiver can determine the user's position and display it   on the unit's electronic map.

  5 more annotations...

• 29 May 06
  

  bernardbates

  Google Earth Global Positioning Satellites

• 22 Apr 06
  

  Ashlyn DeWitt

  at bottom of webpage are links to "GPS Guide for Beginners" and "using GPS with Paper Maps"

  garmin geocaching gps education CTE

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