1. P. Alves and G. Lachapelle University of Calgary USM GPS Workshop Carrier Phase GPS Navigation for Hydrographic Surveys, and Seamless Vertical Datums March 16 – 18, 2004 P. Alves and G. Lachapelle University of Calgary USM GPS Workshop Carrier Phase GPS Navigation for Hydrographic Surveys, and Seamless Vertical Datums March 16 – 18, 2004 Multiple Reference Station DGPS RTK For Sub-decimeter Level 3D Positioning

2. USM GPS Workshop 20042 Overview Network RTK MultiRef™ approach Large-scale network (USCG NDGPS) initial results Medium-scale test network on-going evaluation program In-receiver approach to Network RTK Concept Results (Campania Network) The Future of Network RTK Modernized GPS and GALILEO Network RTK MultiRef™ approach Large-scale network (USCG NDGPS) initial results Medium-scale test network on-going evaluation program In-receiver approach to Network RTK Concept Results (Campania Network) The Future of Network RTK Modernized GPS and GALILEO

3. USM GPS Workshop 20043 Why Use Network RTK? Fixed ambiguities are required for centimeter level 3D positioning. The type of ambiguity is important. Fixed ambiguities do not guarantee cm-level accuracy, especially in height. Fixed ambiguities are required for centimeter level 3D positioning. The type of ambiguity is important. Fixed ambiguities do not guarantee cm-level accuracy, especially in height. Position accuracy with WL ambiguities

4. USM GPS Workshop 20044 Reduction of Measurement Errors To achieve cm-level positioning both L1 and WL ambiguities (for ionosphere-free fixed ambiguities) are required. L1 and WL ambiguity resolution is only reliable with 5 -10 km of the nearest reference station in single reference station mode. Network RTK models the errors that limit the range of ambiguity resolution. To achieve cm-level positioning both L1 and WL ambiguities (for ionosphere-free fixed ambiguities) are required. L1 and WL ambiguity resolution is only reliable with 5 -10 km of the nearest reference station in single reference station mode. Network RTK models the errors that limit the range of ambiguity resolution.

5. USM GPS Workshop 20045 Multiple Reference Station RTK Independent ref. receivers Not Efficient - too many rx -100-80-60-40-20020406080100 -100 -80 -60 -40 -20 0 20 40 60 80 100 Ref. Easting (km) Northing (km) Desired Coverage Area Network of reference receivers

6. USM GPS Workshop 20046 How It’s Done Land-line/Wireless Reference Station Network Control Center Output Corrections Input Observations GPS Receiver User RTCM Data from the reference station network is sent to the control center Control center calculates network corrections and applies them to the RS data User processes single RS (corrected)

7. USM GPS Workshop 20047 U of C MultiRef™ Method Modeling of regional errors using reference stations interactively Three stage process: 1.Resolution of network ambiguities (Fixed or float). Used to measure error levels at the reference station locations 2.Interpolation of the errors to the location of the rover using least squares prediction 3.Application of the corrections to the rover and processing of rover data in real-time Modeling of regional errors using reference stations interactively Three stage process: 1.Resolution of network ambiguities (Fixed or float). Used to measure error levels at the reference station locations 2.Interpolation of the errors to the location of the rover using least squares prediction 3.Application of the corrections to the rover and processing of rover data in real-time

8. USM GPS Workshop 20048 MultiRef™ USCG NDGPS Testing Two sub-networks selected Two scenarios selected for each sub-network East coast sub- network within the NOAA GPS-Met test network Two sub-networks selected Two scenarios selected for each sub-network East coast sub- network within the NOAA GPS-Met test network

9. USM GPS Workshop 20049 North West Network

10. USM GPS Workshop 200410 Observation Domain NW Network RMS (cm) Single baseline NW1NW2 L113.412.012.4 L221.919.720.3 WL16.915.215.7 IF0.70.5 GF8.57.77.9 Improvement (%) NW1NW2 L110.27.4 L210.17.2 WL10.27.4 IF19.721.2 GF10.17.3

11. USM GPS Workshop 200411 Position Domain NW Network NorthEastUp3D Single baseline (cm)5.55.314.816.7 NW1Network (cm)4.24.910.612.4 Improvement (%)23.77.028.325.4 NW2Network (cm)3.95.19.411.4 Improvement (%)28.43.836.331.5

12. USM GPS Workshop 200412 North East Network

13. USM GPS Workshop 200413 Observation Domain NE Network RMS (cm) NE1NE2 Single baseline Net- work Single baseline Net- work L116.412.915.613.0 L226.921.125.621.4 WL21.216.520.717.4 IF0.70.61.0 GF10.68.310.28.5 Improvement (%) NE1NE2 L121.316.2 L221.616.4 WL22.116.3 IF8.76.7 GF21.916.5

14. USM GPS Workshop 200414 Position Domain NE Network NorthEastUp3D NE1Single baseline (cm)4.55.510.913.0 Network (cm)3.95.09.911.7 Improvement (%)12.98.710.0 NE2Single baseline (cm)5.75.114.015.9 Network (cm)5.3 11.914.1 Improvement (%)6.2-3.115.111.9

15. USM GPS Workshop 200415 NOAA GPS-Met Network Troposphere grid model based on over 300 GPS stations Test bed is located in North East USA By 2010, GPS-Met atmospheric delay corrections will cover CONUS Troposphere grid model based on over 300 GPS stations Test bed is located in North East USA By 2010, GPS-Met atmospheric delay corrections will cover CONUS

16. USM GPS Workshop 200416 #4: NE Network + NOAA Troposphere Model

17. USM GPS Workshop 200417 Observation Domain (NE1 + Troposphere Model) NE 1 RMS (cm) Single baselineNetwork Modified Hopfield NOAAModified Hopfield NOAA L116.616.811.712.8 L227.327.719.321.0 WL21.321.715.516.7 IF0.90.7 0.6 GF10.710.97.68.3 Improvement (%)L1L2WLIFGF Single baseline NOAA-1.2-1.6-1.826.4-2.1 NetworkModified Hopfield 29.829.427.523.128.7 Tropo23.422.921.836.322.1

18. USM GPS Workshop 200418 Position Domain (NE1 + Troposphere Model) RMS (cm)NorthEastUp3D Single baseline Modified Hopfield 5.5cm6.518.920.8cm NOAA4.87.413.115.8 NetworkModified Hopfield 6.38.214.017.4 NOAA4.57.012.615.1 Improvement (%)NorthEastUp3D Single baseline NOAA12.513.530.723.9% NetworkModified Hopfield -13.826.026.216.3 NOAA18.1-6.633.427.3

19. USM GPS Workshop 200419 Position Domain (NE1 + Troposphere Model) RMS (cm)NorthEastUp3D Single baseline Modified Hopfield 5.44.925.426.4cm NOAA4.53.919.520.4 NetworkModified Hopfield 4.65.519.120.2 NOAA3.84.414.515.6 Improvement (%)NorthEastUp3D Single baseline NOAA16.819.623.122.7% NetworkModified Hopfield 15.713.424.923.3 NOAA29.48.543.040.8

20. USM GPS Workshop 200420 USCG NDGPS Test Summary Network RTK significantly improves performance in both observation and position domains. However, sub-decimeter level positioning is not possible on this large scale network. A smaller, medium scale network, is better suited to achieving centimeter level 3D positioning. Network RTK significantly improves performance in both observation and position domains. However, sub-decimeter level positioning is not possible on this large scale network. A smaller, medium scale network, is better suited to achieving centimeter level 3D positioning.

21. USM GPS Workshop 200421 U of C Southern Alberta Network (SAN) GPS Reference Stations GPS Reference Stations with MET instruments 306090120 km 14 NovAtel Modulated Precision Clock (MPC) Receivers. 10 Digiquartz MET3A Fan- Aspirated Meteorological Measurement Systems.

22. USM GPS Workshop 200422 SAN Research Activities Network RTK Correction-based Network RTK methods In-receiver Network RTK Error modeling studies Effects of network geometry and topology Integration of Network RTK with other measurement instruments (i.e. inertial measurement units) GPS Meteorology Ground moisture correlation with GPS derived perceptible water vapor GPS storm signatures GPS occultation research Regional tropospheric water vapor modeling Network RTK Correction-based Network RTK methods In-receiver Network RTK Error modeling studies Effects of network geometry and topology Integration of Network RTK with other measurement instruments (i.e. inertial measurement units) GPS Meteorology Ground moisture correlation with GPS derived perceptible water vapor GPS storm signatures GPS occultation research Regional tropospheric water vapor modeling

23. USM GPS Workshop 200423 In-Receiver Network RTK Approach The roving receiver uses integrates the data from all available reference station to achieve network-based high accuracy 3D positions. Land-line/Wireless Reference Station Network GPS Receiver User

24. USM GPS Workshop 200424 Network Processing Rover Positioning Advantages Correction-based Network RTK Control Center Network Processing RS Rover Positioning One-way communication In-Receiver Network RTK RS Two-way communication The rover data can assist with network processing

25. USM GPS Workshop 200425 Campania Network 12 Station network (50 km average inter- receiver distance) Six scenarios tested using 24 hours of data at 1 Hz. RoverReference Station Distance (km) BENEAVEL22 CASEPORT28 AVELARIA33 PADUVLUC35 ISCHPORT38.5 BATTAVEL39

26. USM GPS Workshop 200426 3D Position Accuracy

27. USM GPS Workshop 200427 3D Position Accuracy Summary CaseLength (km) 3D RMS (cm)Improvement (%) Single RS RTK Network RTK AVEL  BENE2212.23.571 % PORT  CASE2812.75.855 % ARIA  AVEL3312.74.763 % VLUC  PADU3518.33.382 % PORT  ISCH38.522.53.485 % AVEL  BATT3926.93.587 %

28. USM GPS Workshop 200428 Future of Network RTK: Modernized GPS and GALILEO Approximately 60 satellites. Three frequency observations per satellite. Past and current research projects: Dilution of precision, availability and reliability with GPS, GALILEO, and combined GPS and GALILEO. Ambiguity resolution and positioning accuracy with three frequency GPS, GALILEO and combined GPS and GALILEO. GPS and GALILEO advanced integration methods (GPS and GALILEO crossed). Triple frequency ionosphere modeling for long baseline ambiguity resolution and precise positioning. All of these research topics are necessary for GPS and GALILEO Network RTK. Approximately 60 satellites. Three frequency observations per satellite. Past and current research projects: Dilution of precision, availability and reliability with GPS, GALILEO, and combined GPS and GALILEO. Ambiguity resolution and positioning accuracy with three frequency GPS, GALILEO and combined GPS and GALILEO. GPS and GALILEO advanced integration methods (GPS and GALILEO crossed). Triple frequency ionosphere modeling for long baseline ambiguity resolution and precise positioning. All of these research topics are necessary for GPS and GALILEO Network RTK.

29. USM GPS Workshop 200429 Effects of Modernized GPS and GALILEO on Single RS RTK Simulated triple frequency data with 3 ppm differential errors Percentage of correctly resolved ambiguity sets Time to fix ambiguities correctly Plotted as a function of distance between the rover and reference station.

30. USM GPS Workshop 200430 Effects of Modernized GPS and GALILEO on Network RTK Faster network ambiguity resolution. More precise measure of the errors at the reference stations. Better modeling of the regional errors. Reduction of measurement errors at the rover. Faster network ambiguity resolution. More precise measure of the errors at the reference stations. Better modeling of the regional errors. Reduction of measurement errors at the rover.

31. USM GPS Workshop 200431 References Fortes, L. (2002) Optimising the Use of GPS Multi-Reference Stations for Kinematic Positioning, Ph.D. Thesis, URL: http://www.geomatics.ucalgary.ca/links/GradTheses.html Julien, O., M.E. Cannon, P. Alves, and G. Lachapelle (2004) Triple Frequency Ambiguity Resolution Using GPS/GALILEO, European Journal of Navigation, June Liu, J., M.E. Cannon, P. Alves, M.G. Petovello, G. Lachapelle, G. Macgougan, and L. deGrout (2003) Performance Comparison of Single and Dual Frequency GPS Ambiguity Resolution Strategies, GPS Solutions, Vol. 7, No. 2, (July Issue), 87 – 100, Springer-Verlag Pugliano, G. (2002) Tecnica GPS Multi-Reference Station Prencipie Applicazione Del Sistema MULTIREF™, Ph.D. Thesis, URL: http://www.geomatics.ucalgary.ca/links/GradTheses.html Pugliano, G., P. Alves, M.E. Cannon, and G. Lachapelle (2003) Performance Analysis of a Post-Mission Multi-Reference RTK DGPS Positioning Approach. Proceedings of the International Association of Institutes of Navigation World Congress (October 2003, Berlin, Germany) Fortes, L. (2002) Optimising the Use of GPS Multi-Reference Stations for Kinematic Positioning, Ph.D. Thesis, URL: http://www.geomatics.ucalgary.ca/links/GradTheses.html Julien, O., M.E. Cannon, P. Alves, and G. Lachapelle (2004) Triple Frequency Ambiguity Resolution Using GPS/GALILEO, European Journal of Navigation, June Liu, J., M.E. Cannon, P. Alves, M.G. Petovello, G. Lachapelle, G. Macgougan, and L. deGrout (2003) Performance Comparison of Single and Dual Frequency GPS Ambiguity Resolution Strategies, GPS Solutions, Vol. 7, No. 2, (July Issue), 87 – 100, Springer-Verlag Pugliano, G. (2002) Tecnica GPS Multi-Reference Station Prencipie Applicazione Del Sistema MULTIREF™, Ph.D. Thesis, URL: http://www.geomatics.ucalgary.ca/links/GradTheses.html Pugliano, G., P. Alves, M.E. Cannon, and G. Lachapelle (2003) Performance Analysis of a Post-Mission Multi-Reference RTK DGPS Positioning Approach. Proceedings of the International Association of Institutes of Navigation World Congress (October 2003, Berlin, Germany)

32. USM GPS Workshop 200432 Additional Information Position, Location, and Navigation Projects: http://plan.geomatics.ucalgary.ca Network RTK at PLAN: http://plan.geomatics.ucalgary.ca/multiref_project.html Geomatics Engineering graduate theses: http://www.geomatics.ucalgary.ca/links/GradTheses.html Position, Location, and Navigation Projects: http://plan.geomatics.ucalgary.ca Network RTK at PLAN: http://plan.geomatics.ucalgary.ca/multiref_project.html Geomatics Engineering graduate theses: http://www.geomatics.ucalgary.ca/links/GradTheses.html