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Real-Time Orbit And Clock Estimation Using PANDA Software

Real-Time Orbit And Clock Estimation Using PANDA Software. Shi C, Lou YD, Zhao QL, Liu JN GNSS Research Center, Wuhan University, China. IGS Analysis Center Workshop 2008 2-6, June 2008, Miami, Florida, USA. Contents. Introduction of PANDA software Strategy for Real-time POD

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Real-Time Orbit And Clock Estimation Using PANDA Software

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  1. Real-Time Orbit And Clock Estimation Using PANDA Software Shi C, Lou YD, Zhao QL, Liu JN GNSS Research Center, Wuhan University, China IGS Analysis Center Workshop 2008 2-6, June 2008, Miami, Florida, USA

  2. Contents Introduction of PANDA software Strategy for Real-time POD Strategy for Real-time Clock Preliminary Results Summary

  3. Introduction of PANDA PANDA : Positioning And Navigation Data Analyst • To derive possible information from GNSS/SLR/ VLBI data in real-time and post-mission • Developed at Wuhan University since 2001 • Current Applications • POD of GNSS&GEO (COMPASS, GPS) • POD of LEOs, CHAMP GRACE (Delft University), COSMIC (JiaoTong Uni. Taiwan) • Huge Network (NEIS) • PPP+Ambiguity-Fixing(GFZ, Nottingham Uni) • …..

  4. PANDA System Structure

  5. New Development: Real-Time • PPP Based Positioning Service System • Real-time GPS orbits • Real-time GPS Satellite Clock Offsets • Precise Point Positioning • Funded by • the Program 973 (No:2006CB701301) • Real-time Precise Positioning Service Prototype System (863) • Real-time POD for LEOs (863)

  6. The Strategy For RT-POD • Two Steps: • Generate NEQs of short ARCs • Combine NEQs to estiamte orbits • Key Issues: • Ambiguity-Fixing • Weight of predicted orbits • Constrained Parameter: • Orbit boundaries • Ambiguities • ZTD, ERP

  7. Parallel Combination • Save the combined NEQs of the last n-1,n-2, …,1 hours • Combined the last hourly NEQ with the saved combined NEQs • Only one combination (red) must be done in real-time Combine hourly NEQs Time-Consuming • Time-Saving • Fast restart with saved (combined) NEQ

  8. Orbital Boundary Constraints Juncture Osculating orbital elements Connected Not connected

  9. Solution with the Constraints NEQs: Juncture constraint:

  10. Stratgy For RT Clocks Two approaches are developed: • Estimate SatClock Epoch-by-Epoch(1hz) • Estimate SatClock Difference between Epoch

  11. Preliminary Results Test Network The distribution of the 70 IGS stations for Real time satellite orbit determination (70stations) Rinex data are inputted as stream through simulated real-time model

  12. Result of RT-POD vs IGS Finals

  13. Result of RT-POD Difference between calculated real-time orbits (Hourly predicted orbits) and IGS final products

  14. Result of RT-CLK vs IGS Finals RMS values of the difference between the calculated SatClock and IGS final products over the period day 198-203 of year 2006 CPUT per epoch on IBM T60 notebook Statistics of the RMS values

  15. Performance of the RT Production Quality of the Real-time SatClock and SatOrbit for the day of year 2006

  16. PPP Based on the RT Production Epoch by Epoch WUHN Station RMS: N: 2.87cm E: 3.23cm U: 7.96cm

  17. Summary • Real-time POD, 5cm • Real-time Clock, 0.18ns • PPP with the Products, 5, 10 cm

  18. Thanks For Your Attention !

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