Starfix HP: High Performance GPS For Offshore Marine Survey, Navigation and Positioning

1. Starfix HP: High Performance GPS For Offshore Marine Survey, Navigation and Positioning • Richard Barker, Dr. Dariusz Łapucha, Tony Wood • FUGRO CHANCE INC.

2. Introduction • Differential GPS: • DGPS: Meter level accuracy over wide area • RTK: Centimeter level accuracy over small area • Starfix High Performance (HP): • Decimeter level accuracy over region using geostationary satellite broadcast • Advance of Fugro Starfix Plus Iono free • DGPS Service

3. Starfix HP Characteristics • High Precision Carrier Phase Measurements • Evaluation of Error Sources  • Proprietary Method of DD Ambiguity Resolution • Network Solution • Long Baseline > 600 km • Offshore Regional Service  • Target Accuracy  10 cm Horizontal 20 cm Vertical Baseline < 1000 km • ITRF 00 Reference 

4. Fundamental HP Measurement 300 m (code) 20 cm (phase) Measurement accuracy is 1% of wave length ==> Code < 3 m ==> Phase ~ 2 mm

5. GPS Error Sources • Satellite Orbit and Clock • Satellite clock and broadcast ephemeris errors are from .5–2m. Orbits to 10m in rare instances • Largely removed by DGPS and orbit correctors • GPS Signal Multipath (reflections) and Receiver Noise • Dependent on receiver type, antenna, and antenna placement .2–5 m • Ionosphere • Region of free electrons from 100–1000 km • Mitigated with models and measurements 5–45 m • Troposphere • The Atmosphere from sea level to 16 km • Mitigated with models and measurements 2–20m

6. The Ionosphere

7. Ionospheric Errors • The Ionosphere Is a Major Error Source for GPS Users • Average daytime ionospheric zenith delay at L1 is 5-15 meters. Can be as much as 36m at equator during solar maximum • At 5 degrees elevation, the total delay is about three times the zenith delay • The Ionosphere Is a Dispersive Medium • Scatters and distorts the GPS signal

8. Current Solar Cycle

9. Regions of Ionospheric Activity

10. Single Frequency BaselineRio de Janeiro - Recifé 1860km 05/16/00

11. Dual Frequency BaselineRio de Janeiro - Recifé 1860km 05/16/00

12. Current Solar Cycle

13. Current Kp

14. The Troposphere

15. The Troposphere • Troposphere Is Another Major Error Source • Tropospheric zenith delay is ~ 2.5 m. Tropospheric mapping functions have a value of about 10 at 5° elevation • Troposphere Delay Can Be Separated Into Two Parts, Each With Its Own Mapping Function • Hydrostatic (dry) term, f (P,T) Accounts for 80-90% of the total delay Can be predicted with high degree of accuracy • Wet term, f (water vapor,T) Highly variable. Significant factor in GOM

16. Starfix-HP Carrier Phase Positioning • Based on dual frequency carrier phase • Ionospheric elimination • Tropospheric estimation • Multiple reference stations • Virtual base station corrections created on-the-fly • Minimizing distance dependent errors • Proprietary DD ambiguity resolution method • Positioning rate independent on reference update rate • High accuracy maintained during short (<60 seconds) reference data outages • Robust decimeter accuracy positioning • Full QC functionality

17. High Performance Service • Introduced in May 2001 in the Gulf of Mexico and the North Sea West Africa South America Europe Persian Gulf Baku Australia South E. Asia • Broadcast via geostationary satellites in L-band • Complements Starfix and Omnistar positioning services • Ongoing expansion of high precision network to support client operations

18. Fugro DGPS Services

19. Fugro DGPS Services • 85 reference stations worldwide • Different methods of reference data delivery to Network Control Centers Houston Perth • Backup connections • ITRF 00 reference worldwide • NAD83 in US (Std. Starfix/Omnistar)

20. HP Test Results • Static Tests in US and Europe • Short (350 km) and Long Baseline (1100 km) • Dynamic Operational Testing (Travelogue) • Kinematic Position Comparison • Heave Comparison (Analog vs. HP) • Real-Time Tide vs Computed • Gravity (acceleration comparison) • Survey Control for Tests • JPL Auto GIPSY • NGS OPUS • SCRIPPS SOPAC • ITRF 00

21. GOM Region Short Baseline Testing (350 km)

22. Short Baseline Static Results(Lafayette)

23. Short Baseline Static Results(Houston)

24. Long Baseline Testing(1100 km)

25. Long Baseline Static Results(Lafayette)

26. North Sea Region Static Testing Oslo

27. Oslo Static Results (300 km Baseline)

28. Rogaland Static Results (300 km Baseline)

29. Oslo-Tromso Long Baseline Results (1150 km)

30. GOM Region Dynamic Testing

31. Dynamic Testing

32. Kinematic Reference Location

33. Surprise At The Dock

34. Kinematic Reference Location

35. Vessel Installation

36. Dynamic RTK Test #1

37. Dynamic RTK Test #2

38. North Sea Region Dynamic Testing Oslo

39. UK HP Test Survey Vessel

40. UK HP Test Vessel

41. North Sea HP Test Vessel

42. North Sea Analog Heave vs HP

43. UK Tide Measurement with HP

44. Marine FLCT Gravimeter

45. Gravity vs HP Acceleration Measurements

46. Gravity Measurement Improvement Velocity • EÖTVÖS Effect (Inherent in gravity taken on a moving vehicle on a rotating earth) • Requires Accurate Course and Speed: • +/-deg. +/-knots Eötvös • STARFIX.HPG 0.05 0.01 0.03 mGal • STD. NAV 0.40 0.04 0.30 mGal

47. Gravity Measurement Improvement Vertical • Sea Level Change Effect (Due to Tides and Weather) Approximately 0.26 mGal/meter of water. • Significant Cause of Line Leveling Errors, especially on 3d surveys when accurate tides are not measured.

48. Current Marine Applications • Improved vertical accuracy for processing of seismic, gravity, bathymetry, other sensors data • Reduced noise for DP vessel positioning • Real-time tide corrections • Precise relative piling measurements • Precise Rig Positioning

49. Precise Relative Pile Installation With HP

50. User Equipment • Versions With: • Integrated GPS receiver, L-band receiver and processor • Supports several dual frequency GPS receiver brands • External monitor and keyboard support • Multiple output formats