G lobal P ositioning S ystem

1. Global Positioning System Vamshi Linga Clint Reitsma

2. Outline • Where it came from • How it works • Error Correction • Galileo and Future Uses

3. Where it Came From • Funded and Controlled by U.S. DOD • Originally Designed for the Military • 1978 First Block of Satellites launched • 1989 Second Block of Satellites launched • 1995 Fully Operational • Korean Flight 007 Crashed – President Ronald Regan guaranteed all GPS signals would be available to the world

4. How it works • Space Segment • Control Segment • User Segment

5. Space Segment • Five to Eight Satellites visible at any time • Each satellite transmits data including both current location and time • Signals move at the speed of light

6. Space Segment

7. Control Segment • Five Control Stations, Master Control at Schriever Air Force Base in Colorado • Monitor satellite health and exact positions • Makes Corrections

8. Control Segment

9. User Segment • Consists of Receivers

10. User Segment • Triangulates by measuring distance using the travel time of radio signals • (Velocity)*(Time)=Distance • Very accurate time required (Atomic Clocks on Satellites) • Along with distance, Satellite position is required • Correction of errors

11. User Segment: Time • Star Spangled Banner Example • Times are very short (0.06 s) • .001 of second error = 200 miles error • Atomic clocks cost $75,000 • Use a forth Satellite Measurement • Pseudo Random Code • Complicated to make unique (not actually random) • Each satellite has own unique code

12. User Segment: Position • Orbits of Satellites are exact and known by receivers (preprogrammed) • DOD monitors and updates ephemeris errors (orbit errors) • Pseudo Random Code includes navigation message with ephemeris error information

13. User Segment Perfect Example Real Example Corrected Example

14. Error Correction • Differential GPS • Cooperation of two receivers • One stationary • One Mobile • Stationary Receiver measures timing errors and provides correction • Uses equation backwards • Uses Known position to calculate time

15. An enabling technology • Marine navigation • Air Navigation • Land navigation • Surveying • Military applications

16. Military applications • Navigation • Tracking • Bomb and Missile guidance • Rescue • Facility Management

17. Navigation • Used to reach and destroy vital enemy installations • Provides the accurate positional data

18. Tracking • Track potential targets • Smart Bombs • Time space position information

19. Missile Guidance • Cruise missiles • Multiple launched Rocket system Vehicles • Reduces the chances of detection and counter Bombardment

20. Rescue and Facility management • Co-Opted with GIS • Can help manage and operates large bases which cover extensive areas.

21. Galileo Project • Inter-operable with GPS and GLONASS • Under civilian control • Four of the first operational satellites will be launched in 2005-2006 • Consists of 30 satellites • 23616 km altitude above the Earth • Coverage from 2008

22. Present developments • Estimated 3.2 billion Euros • Investment for the first quarter • Around 1 billion • India-350 million Euros • China-300 million Euros • More than 600 million by ESA

23. Why does Europe and Asia need Galileo • Civilian uses? • Geo-political implications?

24. Conclusion • Website