GPS System Description Space-based radio navigation system providing: Precise position, velocity and time (pvt) Continuous, worldwide, 24 hour a day coverage Passive; can serve an unlimited number of users All-weather operation U.S. Government system run by the DoD Adminstered by the U.S. Air Force Has large variety of defense and civil applications

GPS Position Determination Technique Time for S1 t2 X2, Y2, Z2 t3 X3, Y3, Z3 X1, Y1, Z1 t1 t4 GPS S3 GPS S2 X4, Y4, Z4 (P2) (P3) GPS S4 GPS S1 S1 Position (P1) (P4) R2 R3 R1 R4 User measures pseudoranges to satellites (R1, R2, R3, R4) User receives and stores data on satellite locations (P1, P2, P3, P4) and their motion ~ P0 User tu 135.1-1 A504f

GPS System Segments User Segment Monitor/ Uplink Stations Space Segment GPS System Segments User Segment Monitor/ Uplink Stations Colorado Springs ¹Hawaii Kwajalein Ascension Island Diego Garcia ²Cape Canaveral, FL Control Segment Headquarters Colorado Springs Schriever AFB Backup OCS Vandenberg AFB ¹ Monitor station only ² Uplink station only Backup OCS Gaithersburg, MD 135.1-1/111-1 V006g

The Navstar GPS Operational Constellation (24 Satellite Baseline Configuration) Note: As of 2004-05, there are about 28-30 S/C in the constellation. 135.1-1/111-1 A401f

Garmin iQue GPS Palm OS