Transcript GPS2006

GPS: Global Positioning
System
April 11, 2016
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
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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 introduce students to GPS
– Teach latitude/longitude
– Take advantage of the wonderful 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 your classroom
• 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