1. 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

2. 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
A504f

3. 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
/111-1 V006g

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

5. Garmin iQue GPS
Palm OS