Introduction to the Global                    Positioning                    System                                  by   ...
WHAT IS GPS?• Satellite based radio positioning system• Developed and maintained by the    U.S. Department of Defense• Mad...
Space Segment
GPS Is An Excellent    Mapping ToolInstantly   gives: Altitude Speed Longitude   and Latitude
How It Works….Trilateration
Math Connection    Step 1       •Suppose we measure our       distance from a satellite and       find it to be 11,000 mil...
Math Connection    Step 2          •Next, say we measure          our distance to a second          satellite and find out...
Math Connection                        Step 3•If we then make ameasurement from a thirdsatellite and find that were13,000 ...
LAND          •USER SEGMENTSEAAIRNEEDTHREE SV’s.
Control Segment• Maintained by the Department of Defense
Sources of Error   Selective Availability (SA Error)   Atmospheric   SV Ephemeris   Multipathing   Poor SV Geometry
EPE              (Estimated Position Error)The higher the EPE,the greater thePositioning error!Good EPE’s range from 10-20...
Shape of the Earth    (datum)
PRACTICAL APPLICATIONS•Navigation   •Sailing, hiking and aviation   •Collecting and locating way-points•Locating Features ...
LOW END UNITS•Capabilities      •20 ft accuracy      •1-12 channel receiver      •Collect only way point data•Cost      •$...
MID-RANGE UNITS•Capabilities      • Sub-meter accuracy with DGPS      • 6-12 channel receiver      • Collects static, mobi...
HIGH END UNITS•Capabilities      • cm accuracy with DGPS      • 12 channel receiver      • Collects static points•Cost    ...
Garmin GPS Receivers   Inexpensive and downloadable   Available locally for less                than $150   Most GPS re...
Okay, lets see how it           works!Zoom out/in         Page ButtonButton                       Power                   ...
Pages In the GPS Unit
SV Visibilityclear view     obstructed viewclear view     obstructed view
Satellite Status    Page   Satellite status    appears while the    unit “finds” the    satellites   Acquisition can    ...
Satellite Status PageSatellite elevation/position       Signal strength       Receiver position
Main Page   The main page    allows user to edit    waypoints, tracks    and routes or    configure system to    personal...
Map Page   Allows you to view    map of current    location,    waypoints and    tracks
Waypoints4                    track           2    3           waypoint 1
Creating Waypoints   Marking waypoints    allows you to    remember and return    to a specific location   Waypoints are...
Finding Waypoints   Pressing “Find”    button will bring up    a list of waypoints   Entering a waypoint    will result ...
Finding Waypoints  Name of WaypointDistance to WaypointBearing to Waypoint          Heading             Speed
What is        Geocaching?Geocaching is a worldwide “scavenger hunt”using GPS to find “caches” of treasure. Theonly rules ...
Links to using GPS into the                Classroom   http://worldofagriculture.org/WOA-precag.htm
Let’s Practice!!   Waypoint #1 – N 39°51.102                    W 095°31.536   Waypoint #2 – N 39°51.081                ...
IntroGPS
IntroGPS
IntroGPS
IntroGPS
IntroGPS
IntroGPS
IntroGPS
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IntroGPS

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GPS technology and how it works!

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IntroGPS

  1. 1. Introduction to the Global Positioning System by Dr. Stephen C. Brown K-State Research and Extension Brown County And Mandy Kern Hiawatha High Agriculture Educator
  2. 2. WHAT IS GPS?• Satellite based radio positioning system• Developed and maintained by the U.S. Department of Defense• Made up of three segments: Space Control User or Ground receivers• Used for obtaining accurate locations anywhere on earth
  3. 3. Space Segment
  4. 4. GPS Is An Excellent Mapping ToolInstantly gives: Altitude Speed Longitude and Latitude
  5. 5. How It Works….Trilateration
  6. 6. Math Connection Step 1 •Suppose we measure our distance from a satellite and find it to be 11,000 miles. •Knowing that were 11,000 miles from a particular satellite narrows down all the possible locations we could be in the whole universe to the surface of a sphere that is centered on this satellite and has a radius of 11,000 miles.
  7. 7. Math Connection Step 2 •Next, say we measure our distance to a second satellite and find out that its 12,000 miles away. • That tells us that were not only on the first sphere but were also on a sphere thats 12,000 miles from the second satellite. Or in other words, were somewhere on the circle where these two spheres intersect.
  8. 8. Math Connection Step 3•If we then make ameasurement from a thirdsatellite and find that were13,000 miles from that one,that narrows our position downeven further to the two pointswhere the 13,000 mile spherecuts through the intersection ofthe first two spheres. •To decide which one is our true location we could make a fourth•So by ranging from three measurement. But usually one ofsatellites we can narrow our the two points is a ridiculousposition to just two points in answer (either too far from Earth orspace. moving at an impossible velocity) and can be rejected without a measurement.
  9. 9. LAND •USER SEGMENTSEAAIRNEEDTHREE SV’s.
  10. 10. Control Segment• Maintained by the Department of Defense
  11. 11. Sources of Error Selective Availability (SA Error) Atmospheric SV Ephemeris Multipathing Poor SV Geometry
  12. 12. EPE (Estimated Position Error)The higher the EPE,the greater thePositioning error!Good EPE’s range from 10-20 feet.Proper pre-mission planning prevents poor positioning!
  13. 13. Shape of the Earth (datum)
  14. 14. PRACTICAL APPLICATIONS•Navigation •Sailing, hiking and aviation •Collecting and locating way-points•Locating Features • Stocking locations or stream surveys • Endangered or sensitive species locations • Locating trails or physical structures•GIS •Collecting GPS data along with attribute data • Mapping and database update•Surveying •Locating Control Points quickly
  15. 15. LOW END UNITS•Capabilities •20 ft accuracy •1-12 channel receiver •Collect only way point data•Cost •$80 - $600•Limitations •Poor reception under tree canopy •No file collection•Applications •Navigation for hiking or sailing
  16. 16. MID-RANGE UNITS•Capabilities • Sub-meter accuracy with DGPS • 6-12 channel receiver • Collects static, mobile and attribute data•Cost • $2,500 - $15,000•Limitations •Not accurate for surveying•Applications • Navigation • Mapping •GIS Update
  17. 17. HIGH END UNITS•Capabilities • cm accuracy with DGPS • 12 channel receiver • Collects static points•Cost • $15,000 - $100,000•Applications • Surveying
  18. 18. Garmin GPS Receivers Inexpensive and downloadable Available locally for less than $150 Most GPS receivers similar in operation
  19. 19. Okay, lets see how it works!Zoom out/in Page ButtonButton Power Button Find ButtonThumbstick
  20. 20. Pages In the GPS Unit
  21. 21. SV Visibilityclear view obstructed viewclear view obstructed view
  22. 22. Satellite Status Page Satellite status appears while the unit “finds” the satellites Acquisition can take several minutes
  23. 23. Satellite Status PageSatellite elevation/position Signal strength Receiver position
  24. 24. Main Page The main page allows user to edit waypoints, tracks and routes or configure system to personal preference
  25. 25. Map Page Allows you to view map of current location, waypoints and tracks
  26. 26. Waypoints4 track 2 3 waypoint 1
  27. 27. Creating Waypoints Marking waypoints allows you to remember and return to a specific location Waypoints are created by pressing and holding thumbstick
  28. 28. Finding Waypoints Pressing “Find” button will bring up a list of waypoints Entering a waypoint will result in “as the crow flies” directions to that
  29. 29. Finding Waypoints Name of WaypointDistance to WaypointBearing to Waypoint Heading Speed
  30. 30. What is Geocaching?Geocaching is a worldwide “scavenger hunt”using GPS to find “caches” of treasure. Theonly rules are to leave something if you take something and do not disturb the cache
  31. 31. Links to using GPS into the Classroom http://worldofagriculture.org/WOA-precag.htm
  32. 32. Let’s Practice!! Waypoint #1 – N 39°51.102 W 095°31.536 Waypoint #2 – N 39°51.081 W 095°31.590 Waypoint #3 – N 39°51.113 W 095°31.417 Waypoint #4 – N 39°51.090 W 095°31.400
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