Real Time Stream Editor for PPP

1. Real Time Stream Editor for PPP Victor Marcelo Santillan Timothy Melbourne Craig Scrivner Walter Szeliga Pacific Northwest Geodetic Array Dept. of Geological Sciences Central Washington University www.panga.org

2. Real Time Stream Editor for PPP Conventional approaches to Real Time Precise Point Position use ionosphere-free combination of code and phase observables to estimate position, troposphere delay, and phase biases for each satellite epoch by epoch. Embedded in the equations, orbits , satellite clocks corrections and differential code biases provided at regular intervals are key to make RTPPP possible. Physical models (tides, ocean loading, phase windup, relativistic effects ) can be predicted and applied as corrections that improve accuracy and help to reduce convergence time. Still we would like to reduce the time for initialization and re-convergence after data gaps or cycle slips.

3. Precise Point Positioning Estimated parameters

4. Real Time Stream Editor for PPP Assuming good orbits, clocks, DCB’s and state of the art physical models. Better initialization, accuracy and convergence can be achieved by screening the observables for outliers, detect cycle slips in the phase observables and properly correct them. Initialization, detection and correction are sometimes done without taking into account the difference in weight of the observables. When cycle slips are detected we can correct them or estimate them. Bad corrections, will degrade the solution. Estimation is a safer approach, but increases the time for re-convergence.

5. Basic Model of GPS Observables1 satellite ,1 epoch

6. Geometry-Free Linear Combinations Neglecting MP12, we have:

7. Real Time Stream Editor

8. Real Time Stream Editor • Update biases b1,b2 when |bw(ti)| < |bw| • -Apply filter constraint b1-b2=bw_fixed • Fix biases when uncertainty is less than 0.5 wl cycles • Reset filter when there is a data gap or cycle slip That’s it!

9. Real Time Stream Editor Wide lane bias test GIPSY 6.1.2 (ninja, in batch mode) vs. RTSE P494 Sierra El Mayor Earthquake 7.1 Mw 04/04/2010

10. RTSEpost-processing results using GOA 6.1.2 P494 Sierra El Mayor Earthquake 7.1 Mw 04/04/2010

11. Features Takes into account different weighting for different observations Stable, lightweight 5 states Kalman filter processing per satellite Facilitates parallel processing Fast convergence and re-convergence < 1.5 min at 1Hz Provides Ionospheric delay as a by-product

12. PPP Results using GOA 6.1.2

13. PPP Results using GOA 6.1.2

14. PPP Results using GOA 6.1.2

15. PPP Results using GOA 6.1.2

16. PPP Results using GOA 6.1.2

17. PPP Results using GOA 6.1.2

18. PPP Results using GOA 6.1.2

19. PPP Results using GOA 6.1.2Orbits, clocks correlation?

20. Thanks,Questions?