1. Geodetic Survey Division EARTH SCIENCES SECTOR Slide 1 Real-Time and Near Real-Time GPS Products and Services from Canada Y. Mireault, P. Tétreault, F. Lahaye, P. Collins, M. Caissy Geodetic Survey Division, Natural Resources Canada (GSD/NRCan) http://www.geod.nrcan.gc.ca IGS Analysis Center Workshop 2008 June 2-6, 2008 Miami Beach, Florida, USA

2. Geodetic Survey Division EARTH SCIENCES SECTOR Slide 2 Outline 1.NRCan Ultra Rapid Products (EMU) 2.CSRS Precise Point Positioning Service (CSRS-PPP) 3.Canadian RT GPS Tracking Network 4.Canadian High Precision RT GPS Wide-Area Correction Service (GPS·C) 5.Final Notes

3. Geodetic Survey Division EARTH SCIENCES SECTOR Slide 3 1. NRCan Ultra Rapid Products (EMU) Orbits and clocks for RT/NRT usage Covers 48h, i.e. 24h estimated and 24h predicted Produced every hour ~1h delay for orbits and ~1.5h delay for clocks Submission to IGS every 6h Predicted orbits used in GPS·C Estimated orbits and 30-sec satellite clocks used in NRT PPP 1.1 Description

4. Geodetic Survey Division EARTH SCIENCES SECTOR Slide 4 1.2 Some Highlights DatesImportant Changes and Highlights 2000-Mar-20 1 st orbit Ultra Rapid 1 st orbit submission to IGS (3h cycle) 2002-Oct-31 1 st clock Ultra Rapid 1 st clock submission to IGS (3h cycle) 2006-Oct-31 5-min Estimating 5-min satellite clocks 2007-Jan-24 1h 1h cycle 2007-Oct-10 30-sec Estimating 30-sec satellite clocks

5. Geodetic Survey Division EARTH SCIENCES SECTOR Slide 5 1.3 Precision * NRCan Solutions (EMU) Orbits * (cm) Clocks * (ns) Estimated portion (24h) 3-4 a 0.15 a 3h prediction 5b5b 0.5 6h prediction 51 12h prediction 62 24h prediction 134 (*) Orbit and Clock Median RMS when compared to IGS Rapid (IGR) (a) Orbits and clocks are used in NRT PPP (b) Orbits are used in GPS·C

6. Geodetic Survey Division EARTH SCIENCES SECTOR Slide 6 2. CSRS Precise Point Positioning (PPP) A Web based global positioning service for single GNSS datasets (currently GPS only; GLONASS planned) Initiated in the Fall of 2003 as next-day service (17h delay) Delay reduced to 90min (May 2008) using NRCan Ultra Rapid orbits and 30sec clocks Process static or kinematic (both with single or dual frequency data) Use of IGS IONEX grids for single frequency processing 2.1 Description

7. Geodetic Survey Division EARTH SCIENCES SECTOR Slide 7 2.2 CSRS-PPP Usage

8. Geodetic Survey Division EARTH SCIENCES SECTOR Slide 8 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1 1.2 1.4 Latitude Longitude Ellipsoidal height Mean Differences (cm) EMU (30sec) IGR (5min) IGS 5min IGS 30sec 2.3 CSRS-PPP Static Positioning Corrections (wrt IGS05) Statistics based on processing of 30 secs data from 24 hour files for ALGO DRAO RESO SASK STJO for GPS Week 1470

9. Geodetic Survey Division EARTH SCIENCES SECTOR Slide 9 2.4 CSRS-PPP Kinematic Positioning Variations (wrt IGS05) 0 5 10 15 20 25 LatitudeLongitudeEllipsoidal height Mean position variations (cm) EMU (30sec) IGR (5min) IGS 5min IGS 30sec Statistics based on processing of 30 secs data from 24 hour files for ALGO DRAO RESO SASK STJO for GPS Week 1470

10. Geodetic Survey Division EARTH SCIENCES SECTOR Slide 10 3. Canadian RT GPS Tracking Network

11. Geodetic Survey Division EARTH SCIENCES SECTOR Slide 11 4. GPS·C: Canadian High Precision RT GPS Wide-Area Correction Service Pseudorange & Phase Processing from IGS-RT + RT-CACS Stations · dtstadtsatdtrop –P3 =  (Xsta,Xsat) + c · ( dtsta – dtsat ) + dtrop +  · dtstadtsatdtropN –L3 =  (Xsta,Xsat) + c · ( dtsta – dtsat ) + dtrop + N +   Xsat provided by EMU (1h cycle) || IGU (6hr cycle) predictions  dtsta, dtsat,dtrop,N estimated in real-time Enhancement of the current code-based system 4.1 Description (1/2)

12. Geodetic Survey Division EARTH SCIENCES SECTOR Slide 12 4.1 Description (2/2) Modeled Effects –Earth & ocean tides –Station & satellite absolute PCV –Relativity –ITRF station velocity –Phase wind-up Parameters Estimated –Station and satellite clocks (white noise parameters wrt VRC) –Station troposphere ZPD (random-walk) –Constant (float) ambiguities RT High Precision Correction Stream –Xsat-BRD @ 120sec (linear over 240sec) –dtsat-BRD @ 2sec

13. Geodetic Survey Division EARTH SCIENCES SECTOR Slide 13 4.2 GPS·C Results

14. Geodetic Survey Division EARTH SCIENCES SECTOR Slide 14 4.3 GPS·C Development Status –Access to 50+ real-time stations globally –Finalizing stress-tests & application robustness improvements –IOC targeted for Fall 2008  Pilot Project / ESS activities Further Refinements to the Phase-based Algorithm & Models –YAW model (Kouba, GPS Solutions (online)) –Un-differenced integer ambiguity resolution with decoupled clocks –Define BRD-independent orbit messages –Define messages for troposphere-mapping grid, satellite DCB’s –Define messages required for PPP ambiguity resolution

15. Geodetic Survey Division EARTH SCIENCES SECTOR Slide 15 4.4 Day-Boundary Clock Jumps / Decoupled Clocks

16. Geodetic Survey Division EARTH SCIENCES SECTOR Slide 16 5. Final Notes IGS Ultra Rapid Combination –Push it to a 3h cycle? Ultimate goal of 1h cycle? –Reduce delay from 3h to 2h? –Need more AC clock solutions to improve precision and accuracy! Global RT GPS Tracking Network –Would provide faster data for Ultra Rapid orbits/clocks turnaround Need for 30sec satellite clocks for Rapid and Ultra Rapid products (NRT users such as PPP)

17. Geodetic Survey Division EARTH SCIENCES SECTOR Slide 17 Information on decoupled clocks –“Isolating and Estimating Undifferenced GPS Integer Ambiguities”, Paul Collins, GSD, NRCan Presented at the Institute of Navigation, NTM 2008, San Diego, January 28-30 2008, session D3. Look also for the corresponding paper in the ION TNM proceeding.

18. Geodetic Survey Division EARTH SCIENCES SECTOR Slide 18 Statistics based on processing of 5 min data from 24 hour files for ALGO for GPS Week 1470

19. Geodetic Survey Division EARTH SCIENCES SECTOR Slide 19 Statistics based on processing of 5 min data from 24 hour files for ALGO for GPS Week 1470

20. Geodetic Survey Division EARTH SCIENCES SECTOR Slide 20 2.5 CSRS-PPP Static Positioning Corrections (wrt IGS05) Hours Statistics based on processing of 30 secs data from 24 hour files for ALGO DRAO RESO SASK STJO for GPS Week 1470

21. Geodetic Survey Division EARTH SCIENCES SECTOR Slide 21 Y. Mireault, P. Tétreault, F. Lahaye, P. Collins, M. Caissy Geodetic Survey Division, Natural Resources Canada (NRCan Natural Resources Canada (NRCan) has been involved in producing and promoting GPS Real-Time (RT) and Near Real-Time (NRT) products and services for more than 10 years. Key products and services, like 1Hz GPS station data, Ultra Rapid GPS orbits/clocks, GPS Precise Point Positioning (PPP) and GPS corrections (GPS·C), have been developed and refined over the past several years. This presentation will focus on current RT and NRT products and services developed by NRCan and made available to users in Canada and world wide. First, a description of the RT GPS tracking network covering Canadian territory and used within GPS·C will be given. Next, NRCan’s hourly Ultra Rapid GPS satellite orbit and 30- sec satellite clock estimation strategy will be presented. Then, we will discuss NRCan’s PPP, a free online post-processing service using IGS and NRCan’s orbits/clocks and IGS IONEX products to allow GPS users world wide to compute better-accuracy positions from their single/dual frequency datasets observed in static/kinematic mode. Finally, an overview of the RT GPS wide-area correction service (GPS·C) distributed nationally through the Canada-wide DGPS will be given. Real-Time and Near Real-Time GPS Products and Services from Canada