1. 1 GPS Observations and data-processing. Sat07_81.ppt, 2007-10-23. Observations: Pseudo-ranges from P-code obs. Pseudo-range differences from Doppler shift Carrier-wave phases or phase-differences Travel-time differences from interferometric measurements

2. 2 GPSPhases. Sat07_81.ppt, 2007-10-23..

3. 3 GPS Carrier (CR)-phases. Sat07_81.ppt, 2007-10-23..

4. 4 GPS Code and Carrier Phases. Sat07_81.ppt, 2007-10-23. T is the satellite time t is the receiver (RCV) time t as subscript: transmitted signal r as subscript: received signal f CD = code-frequency f CR =carrier frequency Then Code: Φ CD (T t )=T tSV f CD Carrier: Φ CR (T t )=T tSV f CR

5. 5 GPS Code and Phase. Sat07_81.ppt, 2007-10-23. -

6. 6 GPS. Sat07_81.ppt, 2007-10-23. n

7. 7 GPS. Pseudo-range. Sat07_81.ppt, 2007-10-23..

8. 8 GPS Phase. Sat07_81.ppt, 2007-10-23..

9. 9 GPS Data differencing. Sat07_81.ppt, 2007-10-23. Using linear combinations, it is possible to eliminate various terms: Differences: between different stations satellites epochs However: noise increases ! Notation: i,j receivers (sub-scripts), p, q, satellites (super-scripts) t 1, t 2 epochs at position 1 and 2 of p. q. Pseudo ragnes: PR p 1i (example)

10. 10 GPS Observations. Sat07_81.ppt, 2007-10-23.

11. 11 Single differences, two receivers. Sat07_81.ppt, 2007-10-23.

12. 12 Double-differences. Sat07_81.ppt, 2007-10-23.

13. 13 Triple and other differences. Sat07_81.ppt, 2007-10-23.

14. 14 GPS Linear combinations. Sat07_81.ppt, 2007-10-23.