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Pilot Project Report: Feasibility of using Natural Resources Canada’s High Precision GPS Corrections (HPGPS*C) Service for Hydrographic Surveys in the Canadian Arctic FGCB Infrastructure Task Group Meeting, March 31, 2014.

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  1. Pilot Project Report: Feasibility of using Natural Resources Canada’s High Precision GPS Corrections (HPGPS*C) Service for Hydrographic Surveys in the Canadian ArcticFGCB Infrastructure Task Group Meeting,March 31, 2014 Serge Lévesque, Fisheries and Oceans Canada, Canadian Hydrographic Survey, Hydrography, Nautical Geodesy

  2. Overview • Survey areas in the north • Description of the CHS survey launch and positioning systems used in Hudson Bay and in the Arctic. • Comparison of Positioning Results • Results from CHS Pacific testing • Summary

  3. Northern Surveys: CHS Central & Arctic Fall 2013

  4. Northern Surveys: Fall 2013 • Inukjuak: September 18 • Post-Processing Kinematic (PPK) station • Hall Beach: September 21-22 • HP-GPS*C outage on October 21st (1 day) • Fury and Hecla Strait: September 24-27 • Quaqtaq: October 02 • Pike-Resor (approaches to Iqaluit): October 04-05

  5. CHS Central & Arctic survey launch Petrel (Hudson Bay and Arctic) • Multibeam sonar EM-3002 • POS-MV integrated inertial system • GNSS antenna split between two receivers: • POS-MV with WAAS (main) and NovAtel with HP-GPS*C • INMARSAT terminal : • HP-GPS*C signal via internet through IP connection

  6. Post-Processing Kinematic (PPK) station • PPK station in Inukjuak: 9 hours with NovAtel receiver, • Over CHS bench mark 2-1962

  7. Northern Surveys: CHS Central & Arctic Fall 2013

  8. Bathymetry: PPK and POS-MV corrected navigation

  9. Inukjuak:selection of survey lines 16, 17, 34 and 35 • Survey Lines in North-South or East-West direction • During periods of convergence of HP-GPS*C, within 10 cm standard deviation • Best conditions for position accuracy

  10. Sky View in Inukjuak GPS + GLONASS • 58°25’N • 9 hours 30 minutes of survey • Between 12 and 22 satellites in the sky: GPS + GLONASS • Of these, between 6 and 13 GPS satellites in the sky • HP-GPS*C only applies to GPS satellites GPS only

  11. Convergence of HP-GPS*C: Lines 16, 17, 34 and 35 • Requires 20 to 25 minutes for solution of HP-GPS*C to converge to 10 cm on NovAtel receiver 17 35 34 16

  12. Number of satellites and Ambiguity resets for NovAtel receiver on the Petrel from NRCan PPP post-processing: September 18, 2014 Loss of convergence/reset happened at high percentage of ambiguity resets: GPS outage

  13. Positions differences • Inukjuak, best site for analysis: • Very good weather • Best conditions for the testing of HP-GPS*C: few resets • At 58°25’N, INMARSAT is still high on the horizon • GPS/GLONASS constellations still high in the sky • PPK station in operation throughout the survey • Post-Processing Kinematic was used as reference • PPK corrected positions to produce the final bathymetry • NRCan PPP was calculated as a secondary check

  14. Horizontal differences

  15. Relative positions of POS-MV and NovAtel • Reference Point (RP) at location of the Inertial Motion Unit • POS-MV offsets all positions to the sensor head • Lever arms applied by POS-MV to take offsets to RP, roll , pitch and heading (gyro) into consideration. • Multibeam sensor head is 0.49 m below Reference Point (RP) • GPS/GNSS antenna is • At 4.3 m behind the RP • At 0.51 m to the right of the RP • NovAtel with HP-GPS*C positions referenced to antenna • For comparison purposes: offsets & lever arms calculated manually

  16. Ellipsoidal heights comparisons

  17. Ellipsoidal Heights differences

  18. Northern Surveys: CHS Central & Arctic Fall 2013

  19. Fury and Hecla Strait • Difficult convergence • Frequent resets • Loss of correction • Noisy GNSS/GPS data: GPS outages?

  20. Northern Surveys: CHS Central & Arctic Fall 2013

  21. Pike-Resor: Approaches to Iqaluit

  22. Possible reasons: low signal in the North • INMARSAT antenna too close to GPS antenna • Satellites low on the horizon • Solar flares, sun activity • Bad weather, rapid changes in the launch’s attitude • INMARSAT at low (10° or less) elevation • Presence of mountains close by (to the south) • Amplified low elevation due to motion of the launch

  23. CHS survey launch Shoal Seeker (Pacific) • GPS antenna split between two receivers: • One is always the POS-MV (Trimble): with RTK or CG DGPS • Second is either: NovAtel with HP-GPS*C, C-NAV, or NovAtel CORRECT • Dynamic and static testing (Patricia Bay, B.C.): • Static measurements • Monitoring tide cycle on vessel at dock • Testing at sea + PPK station at Institute of Ocean Science • Connection to Internet for HP-GPS*C signal: • INMARSAT terminal through IP • Cellular modem

  24. Pacific Testing in Pat Bay by Dr David Dodd

  25. Saltspring Island, B.C.by Dr David Dodd

  26. Summary • Good results obtained in the south at Inukjuak and on the Pacific Coast • At higher latitudes in the north, convergence was resetting too often • More processing and analysis of the data is required • The Iridium terminal could not be used due to lack of space on the launch

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