2. Global Positioning System

3. What is GPS ? A very precise positioning system Developed and maintained by the US Department of Defense (DOD) Satellite Based * 24 satellites * 20,200 km high orbit

4. Characteristics of GPS Free Precise Reliable Anytime & anywhere All weather Unlimited user capacity Accurate(precise) Almost!

5. Segments of GPS 1. Space Segment A constellation of 24 satellites 2. Monitor Station A network of earth-based facilities 3. Users & Equipment Source:Trimble

6. Segments of GPS Source:Trimble 1. Space Segment A constellation of 24 satellites

7. GPS Monitoring Station

8. How GPS Works ……… Uses measurements from 4+ satellites Distance = travel time x speed of light Source:Trimble

9. Determining GPS Position Suppose the distance from Satellite A to our position is 11,000 miles At this point we could be located anywhere on the specified sphere Satellite A + Next, let us take another measurement from a second satellite, Satellite B Satellite B + Now our position is narrowed down to the intersection of theses two sphere

10. Satellite C + Determining GPS Position Satellite A Satellite B + + Taking another measurement from a 3 rd satellite narrows our position down even further, to the two points So by ranging from 3 satellites we can narrow our position to just two points in space These points are located where the 3 rd sphere cuts through the the intersection of first two spheres

11. Three Dimensional (3D) Positioning

12. Determining GPS Position

13. Common use of GPS A.GIS data collection & mapping B. Navigation C. Recreation

14. GPS for Navigation

15. GPS in recreation

16. GPS in Farmland

17. GeoXT Versus Garmin Mostly used for GIS data collection Mostly used for recreational purposes

18. Websites http://www.garmin.com/en-US https://store.trimble.com/OA_HTML/ibeCZ zpHome.jsp?minisite=10140https://store.trimble.com/OA_HTML/ibeCZ zpHome.jsp?minisite=10140