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Additional ArcView Training Materials by Marc Albrecht Univ. of Nebraska at Kearney Department of Biology

Additional ArcView Training Materials by Marc Albrecht Univ. of Nebraska at Kearney Department of Biology. Part II (optional): Introduction to the Global Positioning System. The Global Positioning System. A constellation of 24 high-altitude satellites Cost: over $12 billion US tax dollars.

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Additional ArcView Training Materials by Marc Albrecht Univ. of Nebraska at Kearney Department of Biology

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  1. Additional ArcView Training Materials by Marc AlbrechtUniv. of Nebraska at KearneyDepartment of Biology Part II (optional): Introduction to the Global Positioning System

  2. The Global Positioning System • A constellation of 24 high-altitude satellites • Cost: over $12 billion US tax dollars

  3. GPS Satellites • More than 24 up at all times. • Three atomic clocks per satellites. • Built to be resistant to blocking and jamming. • Rockwell: • 11,000 miles • 17 feet • 1900 lbs.

  4. Ranging, why 3 needed? GPS Satellite

  5. 4 ‘birds’ (as we say) for 3-D fix

  6. Relative Timing • Each satellite sends out the same sequence of signals • The receiver calculates the shift between identical parts of the code • Analogy: Stand on 20 yard line of stadium – two friend yell to you from each goal line at the same moment. Time difference

  7. GPS Uses • Natural Resource based • Animal/plant locations • Soil/water sampling locations • Human-based: • Air and sea navigation • Emergency Services Locating • Airplane landing systems • Car-based direction services.

  8. Why is the system not perfect? What is this? • Error sources • Atmospheric • Multipath scatter • Positional error • Dept. of Defense introduced error – removed under Clinton • Cheap GPS Units • Limited satellite channels • Poor internal processors. These are the real numbers! Today, first number is closer to the 6m.

  9. One solution – Differential GPS • This system uses two receivers to eliminate much of the signal error • This increases accuracy to a few centimeters with good units.

  10. Differential GPS Resources • Real-Time Correction • What is it? • Coast Guard and USGS Signals • Third – party contractors

  11. Another way to do DGPS • Post-Processed Correction • What is it? • What is RINEX? • State Base Stations • www.sso.state.ne.us/gps/ • USGS Sites • Nice downloads!

  12. Where to get more information • Univ. of Nebraska at Kearney • Marc Albrecht: albrechtm@unk.edu and http://gis.unk.edu • Steele Becker: beckers@unk.edu • Univ. of Nebraska CALMIT= www.calmit.unl.edu • Rick Perk = rperk1@unl.edu • Marcus Tooze = mtooze@gisworkshop.com • Nebraska Natural Resource Commission • Steve Rathje = rathje@nrcdec.nrc.state.ne.us* • Natural Resource Districts • Doug Steinke = steinke@nrcdec.nrc.state.ne.us

  13. If you really want more! • Univ. of Neb. At Kearney • 2-day ESRI-certified workshops in ArcView • UNK classes (Biology 430/830) • ESRI (Environmental Systems Research Institute), the people who make ArcExplorer and ArcView - www.esri.com • online classes • downloadable tutorials.

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