What is GPS?

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What is GPS - Environmental Monitoring

Global Positioning Systems or Genius Pinpointing Systems?

Did you know that GPS’ (also known as global positioning systems) are just one of the satellite navigation systems that we have on earth?

GPS’ were first created and introduced by the United States Department of Defense, with the accompanying launch of 24 satellites into the earth’s orbit. Eventually, this system evolved and adapted from sole military use, to the wide-spread civilian use of the GPS’ we see today.

Why are GPS’ so rad? Well because….

  • They work in all-weather systems
  • Are available for use 24/7
  • Can be used anywhere in the world
  • And there are no subscription or sign-up fees to use them

But how do they work? It may seem like magic but really it’s actually just wicked science and technology at work. When you receive a location through a signal with a GPS, it is because the satellites orbiting the earth are actively transmitting FM radio signals to these handheld GPS devices. From here, GPS’ receive these FM signals and calculate the lag time it takes the signals to travel from the satellite to the GPS unit. At this point a simple formula is applied to the figure out this distance – called trilateration. Trilateration is calculated by measuring the distances to a known point. So by using three satellites that are trilaterated to, the GPS can help the user determine their location on earth. Essentially the GPS unit is comparing the time of the signal that was transmitted by the satellite, to the time it was received by the GPS unit. Using 3 satellites to trilaterate the distance provides the GPS with a 2-Dimensional location. If a 4th satellite can be used in measuring the distance to the GPS, a 3-Dimensional location is given, can account for elevation. Therefore, the more satellites that are used, the finer the location can be pinpointed. As well, typical handheld GPS’ have an accuracy of anywhere between 10-3 meters.

What kind of information can a GPS provide   me with?

  • Speed
  • Bearing
  • Track trips, determine distances
  • What the sun rise or sunset will be at a location
  • What the average and moving speed of the GPS user is
  • Glide ratio
  • As well as the distance to the destination

Other GPS fun facts:

  • There are 24 satellites that make up the GPS’ satellite constellation in the sky.
  • This is comprised of 4 different orbits, with 6 satellites per orbit.
  • They orbit the earth twice per day.
  • Each satellite last about 10 years.
  • The satellites are powered by solar power and transmit signals at about 50 Watts.
  • They weigh 2000lbs & measure 17 feet across


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