GPS works by using a network of satellites that transmit radio signals to receivers on Earth. These signals allow GPS receivers to calculate their position by determining distance from multiple satellites using trilateration. The document discusses factors that can impact accuracy, such as satellite geometry and signal interference, and provides best practices for using GPS to collect data for mapping trails.

3. Global Positioning System Control Segment Space Segment User Segment

7. How does it work?

9. How does it work Speed of Light x Travel Time Distance Time signal left satellite Time current

14. Accuracy

18. Reduced Accuracy and Errors

24. Signal Interference Ionosphere Solid Structures Metal Electro-magnetic Fields

26. Wide-Area Augmentation System (WAAS)

28. WAAS If WAAS signal intermittent- WAAS correction for SV 19 No WAAS correction for SV 11

29. WAAS WAAS satellites GPS Constellation WAAS Control Station (Position known) GPS receiver (Position with errors) 25 Reference Stations (Position known)

32. Taking Measurements

35. Transferring Information

37. Submission Forms

38. Questions?