1. 1 Sat07_73.ppt, 2007-10-23. GPS Definition. Precise satellite navigation-system, which after 1993 will give users a 3-D position and velocity as well as a precise time anywhere on and in the vicinity of the Earth

2. 2 Sat07_73.ppt, 2007-10-23. GPS /

3. 3 3 SEGMENTS: Space-segment Control-segment User-segment

4. 4 Sat07_73.ppt, 2007-10-23. GPS, Configuration /

5. 5 Sat07_73.ppt, 2007-10-23. GPS Constallation 18 satellites and 4 reserve in 6 planes Lifetime: 7.5 years 6 planes, 60 0 separated Inclination: 55 0 Semimajor axis: 26000 km Period: 11 hours 58 min

6. 6 Sat07_73.ppt, 2007-10-23. Satellitbaner GPS, i= 55 0.

7. 7 Sat07_73.ppt, 2007-10-23. GPS satellite

8. 8

9. 9 Sat07_73.ppt, 2007-10-23. GPS, Observation principle

10. 10 Sat07_73.ppt, 2007-10-23. GPS signal

11. 11 Sat07_73.ppt, 2007-10-23. GPS position and velocity determination.

12. 12 Sat07_73.ppt, 2007-10-23. GPS signal

13. 13 Sat07_73.ppt, 2007-10-23. GPS Signal (II) L1: 154 x 10.23 MHz = 1.57542 GHz L2: 120 x 10.23 MHz = 1.22760 GPz Whar is the wave-length ? Modulated with P-Code: 10.23 MHz = ca. 30 m, Repeated after 266 days = 7 days for 1 satellite Zero at 0.0 UT Saturday/sunday Only L1 modulated with C/A code: 1.023 MHz = Ca. 300 m

14. 14 Sat07_73.ppt, 2007-10-23. Satellite-orbits– orbit changes. 16 parameters, Updated every hour

15. 15 Sat07_73.ppt, 2007-10-23. Satellite orbit parameters for GPS Mean-anomali Mean-anomaly change Excentricity Square-root semimajor axis Rectacensionen Inclination at t 0e Perigæums argument Tidsændring af rectac. Time-change of i Corection of f+ Correction of r Reference-time /

16. 16 Sat07_73.ppt, 2007-10-23. Satellite orbit error - relative positioning Influence of orbit-error on position determination Reduced if we determine difference-vector Relativ precision: db/b dr (m) b(km) db 1 ppm 20 10 1cm 0.1 ppm 2 10 0.1 100 1

17. 17 Sat07_73.ppt, 2007-10-23. GPS, error-sources.

18. 18 Sat07_73.ppt, 2007-10-23. Differentiel GPS

19. 19 Sat07_73.ppt, 2007-10-23. GPS, position-error.