1. An introduction to GPS technology

2. Thank you to the University of New Hampshire Cooperative Extension Program for providing these materials!

3.  Developed by the US Department of Defense  Satellite-based  Designed to provide positioning and timing information:  24 hours/day, 7 days/week  Under any weather conditions  Anywhere in the world  Three components – space, ground, user

4.  24 satellites in the US constellation  Orbit every 12 hours at 12,550 miles  4 satellites in each of the 6 orbital planes  Transmit a uniquely coded radio signal  Equipped with onboard atomic clock UNH Cooperative Extension 2008

5.  Ground-based monitoring and upload stations  Control orbit and timing information http://www.gps.gov/systems/gps/control/

6.  Both military and civilian users  Navigation and positioning applications on land, sea, in the air and in space http://usmilitary.about.com/od/armyweapons/a/gps.htm

7. 1. The receiver picks up the signals from the satellites 2. Uses the signal travel time to calculate distances to the satellites 3. Triangulates to determine position of the receiver

8. Earth Space UNH Cooperative Extension 2008 1. The receiver picks up the signals from the satellites

9. Earth Space UNH Cooperative Extension 2008 2. Travel time of signal from satellite used to calculate distance 0.059 sec. = 11,000 miles 0.075 sec. = 14,000 miles 0.070 sec. = 13,000 miles 0.065 sec. = 12,000 miles

10. 3. Receiver triangulates to determine position of the receiver UNH Cooperative Extension 2008

11. 3. Receiver triangulates to determine position of the receiver UNH Cooperative Extension 2008

12. 3. Receiver triangulates to determine position of the receiver UNH Cooperative Extension 2008

13. 3. Receiver triangulates to determine position of the receiver UNH Cooperative Extension 2008

14. 3. Receiver triangulates to determine position of the receiver You are here!

15.  Capable of sub- centimeter accuracy  Bulky, expensive  High-precision applications such as surveying, geodetics

16.  Capable of 10 meter accuracy (<1 meter with differential)  Light-weight, portable, less expensive  Resource mapping and navigation applications

17.  Capable of 10 meter accuracy (capable of <3m with differential)  Light-weight, cheap!  Navigation applications and basic mapping applications.

18. 1. Geodetic  High quality surveying of fixed positions 2. Mapping  Collection of GPS data with large amounts of auxiliary data and strict data quality control 3. Handheld  Collection of GPS data with good data quality for more limited budgets

19. Don’t forget your map and compass!

20. This GPS presentation includes slides from Trimble Navigation and Tom Luther, USDA Forest Service.