This work is supported by the National Science Foundation’s Transforming Undergraduate Education in STEM program within the Directorate for Education and Human Resources (DUE-1245025).

GPS is everywhere!!

THE GLOBAL POSITIONING SYSTEM

• 24-32 satellites• 20,200 km altitude• 55 degrees inclination• 12 hour orbital period• 5 ground control stations• Need 4 satellites to be

accurate• Each satellite passes over a

ground monitoring station every 12 hours

http://www.colorado.edu/geography/gcraft/notes/gps/gps_f.html

HOW ACTUAL LOCATION IS DETERMINED

• Receiver position is triangulated using at least 3 satellites, 4th needed to adjust the receiver’s time.

CONSUMER-GRADE GPS ACCURACY• Horizontal: +/- 10 m (30 ft) error• Vertical: +/- 15 m (45 ft) error

Your location is:37o 23.323’ N

122o 02.162’ W

5

High-precision GPS accuracy

• Horizontal: +/- 1 cm error• Vertical: +/- 10 cm error