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					GPS: Global Positioning
       System
Global Positioning Systems
        • GPS is a revolutionary
          navigation system
          – 24 satellites orbiting the
            earth
          – Provide location within
            metres or less anywhere on
            the globe.
          – Now available in many cars
            as an option
          – Created and operated by
            the US Department of
            Defense
     More about GPS satellites

• Constellation of 27 satellites
   – (24 active + 3 spare)
• Orbit 12,600 miles above earth
   – (10,900 nautical miles)
• Satellites in 12 hour orbit
• First satellite launched in 1978, 24th became
  operational in 1994
• Selective availability was removed in May,
  2000
   – Handheld receivers are now much more accurate
         How does GPS work?

• Measuring distance by measuring time
  – Satellites send coded signals indicating
    their position in space and the exact time
    the signals are being sent
  – Receivers use the time it takes signal to
    travel from satellite to receiver to determine
    distance from satellite to receiver
  – Information from multiple satellites is used
    to determine position through „triangulation‟
How does GPS work?
     More about GPS receivers

• A GPS receiver's job is to locate
  four or more satellites, figure out
  the distance to each, and use this
  information to deduce its own
  location.
  – Hand-held receivers for recreational
    use with accuracy of 10-15 metres
  – Vehicle mounted receivers for
    navigation or agricultural use with
    accuracy of < 1 metre
  – Backpack or tripod mounted
    receivers for surveying use with
    accuracy of 5 – 10 centimetres
     More about GPS receivers
• Receivers require clear line-of-sight; thus,
  they will not work indoors or where tall
  objects obscure the sky
   What‟s so cool about GPS?

• GPS units
  – Can be used as a digital compass
  – Can be used to determine ground speed
  – Can store landmarks (locations)
  – Can be used for dynamic routing
  – Can be used for mapping applications
           Applications of GPS
•   In-vehicle Navigation (car, boat, airplane)
•   Asset Management
•   Construction
•   Geologic Research & Mining
•   Military Navigation and Operations
•   Mapping & Surveying
•   Precision Agriculture
•   Public Health
•   Public Safety
•   Wireless Communications
GPS in the classroom

E C Drury Scavenger Hunt
      Integrating GIS and GPS

• Collect a series of latitude and longitude
  points using GPS receivers
  – add them into an existing digital map
• Skills in
  – data collection/creation
  – GPS reading
  – observation
• Digital photos
                Geocaching

• A great way to learn how to use a GPS
  – Learn latitude/longitude
  – Take advantage of the features and capability of
    your GPS unit
• An entertaining adventure for GPS users
  – Individuals and organizations all over the world
    have set up caches and shared the locations of
    these caches on the Internet
  – Participate in a cache hunt to find an existing
    cache or create your own
• www.geocaching.com
          Classroom projects

• There are many ways you can incorporate
  GPS data collection into Grade 9 Geography
• Possibilities include
  – a virtual trail in your area
  – mapping the locations of litter and garbage cans to
    determine if there is a relationship, and if more
    garbage cans are necessary
  – collecting data about tree types and locations on
    school grounds and beyond
  – gathering water samples from a local stream and
    taking GPS readings at each location
  – orienteering/navigating (hiking, boating, biking,
    driving)
                  Getting started

• GPS units - Garmin eTrex
   – perfect for introducing students to field
     data collection and the power of GPS
   – industry's smallest and lightest
     handheld GPS receiver
   – sleek waterproof housing will fit in
     your shirt pocket and weighs only 5.3
     ounces
   – a 12 channel parallel receiver,
     differential ready, with a built-in patch
     antenna
   – runs for 22 hours on just two AA
     batteries
• Pencil, clipboard, paper
     Getting started - additions

• Connection cables for your GPS units
  – Allow you to download data from your GPS unit to
    your computer
  – Free extension available to convert to shapefile
• Local data
  – Create a base map for viewing the data you have
    collected
  – Provides context and other features for GIS
    analysis with ArcView
• Digital camera
            Collecting data

• Collect data in the field using GPS
  – Write down point coordinates and
    additional data observations
                  - OR -
  – Use tracking function of your unit to store
    points, lines, or polygons, and write down
    additional observations
     Using the data you collect

• Manually enter the coordinates and
  observations into a table (Excel, etc.)
  – Save as a .dbf file
  – Add to ArcView
  – Use “Add X,Y” or “Add Event Theme” to
    create points on your map
                  - OR -
• Use your GPS unit cable to download
  the data from the unit to your computer
      For more information…

• Books from ESRI Press
  – Integrating GIS and the Global Positioning
    System
    • Karen Steede-Terry
  – Fun with GPS
    • Donald Cooke
  – Community Geography: GIS in Action
    • Kim Zanelli English and Laura S. Feaster
      For more information…
• Lessons on the ESRI Canada website
  – http://k12.esricanada.com
  – Integrating GIS and GPS (ArcView 3.x)
  – Exploring Pukaskwa National Park
    (ArcView 8.x/9.x)
• Garmin website
  – http://www.garmin.com/
• Trimble GPS
  – www.trimble.com/gps
• How stuff works
  – www.howstuffworks.com

				
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