GPS

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(No Transcript)
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GPS

• Mr.Voicheck
• 8/2/05

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GPS - Overview

• What is GPS
• Facts about GPS
• What you can do with it
• Putting satellites in Space
• 2D Trilateralation
• 3D Trilateralation
• Who uses GPS
• Problems with GPS

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What do you think GPS is?
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What is GPS?

• GPS Global Positioning System
• A system of satellites and receiving devices used
  to compute positions on Earth. (terralink.co.nz)
• A world wide radio-navigation system that was
  developed by the US DoD. (ceva-dsp.com)
• A system of satellites that allows ones position
  to be calculated with great accuracy by the use
  of an electronic receiver. (chron.com)

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GPS Satellite Setup
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What is GPS? cont

• Definition
• A network of satellites that continuously
  transmit coded information which makes it
  possible to precisely identify locations on earth
  by measuring distance from the satellites.
• It allows you to use a handheld receiver to
  figure out where you are in the world without
  having to know where you are. You dont have to
  be smart to work these things.

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Facts about GPS

• Also known as NAVSTAR
• Navigation Satellite Timing and Ranging
• 24 Satellites (create a blanket)
• 21 active satellites, 3 spares
• 12,000 Miles above Earth
• Satellites transmit low power frequency
• 7,000 Miles per hour
• Solar Powered
• Battery backup (in case of Solar Eclipse)
• Rocket boosters on each side for steering
• Two rotations a day

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Facts about GPS cont

• First GPS satellite launched in 1978
• A full setup was established in 1994
• Cost over 12 Billion dollars
• President Ronald Regan supported GPS

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What can you do with GPS?

• A GPS receiver will tell you the following
• Distance traveled
• Current speed (usable to over 900 MPH)
• Average speed of travel
• How long youve been traveling
• Where youve been and how to retrace your path
• Estimated time of arrival (ETA) when destination
  is known.
• Keeps track of way points (imaginary markers)

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How the satellites get put in Space
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How GPS works 2D Trilateralation

• For example, imagine you are 300 miles from
  Boise.

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How GPS works cont

• You are also 400 miles from Minneapolis

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How GPS works cont

• You are also 300 miles from Tucson
• Which puts you in Denver
• You need three circles to intersect your exact
  location

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How GPS works 3D Trilaterlation

• Exactly the same as the circles, but it uses
  spheres.

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Who uses GPS?

• Military
• Police
• Fire Department
• Ambulance
• Civilians
• Boaters
• Hikers
• Drivers
• Truckers
• You

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Problems with GPS

• Ionosphere and troposphere delays
• Signals slow as they pass through atmosphere
• Receiver clock errors
• Each base unit has its own timing clock
• Signal multi-path
• GPS signal is bounced off objects like a building
  before it reaches the receiver, increasing the
  time.
• Orbital Errors
• ephemeris errors errors in satellites
  reported location.

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Problems with GPS cont

• Doesnt work indoors
• Doesnt work around buildings
• When it does, it has problems
• Doesnt work underwater
• Satellites only last 10 years
• Accuracy ranges from of 3-5ft to 20-40ft
• Depends on of satellites

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GPS deceived in the movies

• 007 Never Dies
• Impossible to distort GPS signals
• Enemy of the State
• Doesnt work in buildingsyet.
• The Art of War
• Uses the wrong GPS unit
• Demolition Man
• Cars cant navigate themselves yet.

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GPS related Websites

• www.geocaching.com
• Treasure hunt using gps
• www.garmin.com
• Company who sells gps units

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End of Presentation

• Questions?
• What do you want to do with GPS?

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Further Reading

• Look up
• GPS
• Coordinate System
• GMT
• Latitude
• Longitude
• Etc..

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Activity

• Insert really cool activity here
• Handout similar to 2D trilateralation

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References

• www.garmin.com
• www.howstuffworks.com
• www.navicom.co.uk
• www.nr6ca.org
• www.nasm.si.edu