Post on 16-Jun-2020
Evaluation of GNSS-derived Tidal Information in Hydrographic Applications
Ben Dean Hydro14 - 28th October 2014 Aberdeen, United Kingdom
Introduction
• Precise Point Positioning (PPP) • C-Nav • Vertical Reference Surfaces • Testing Methodology • Results • Conclusion • Future…………
• Absolute positioning technique • Utilises improved orbit and clock products • Allows a stand-alone GNSS receiver to
achieve centimetric positioning accuracy • Cost effective • Global (No spatial decorrolation) • Sparse global network (40 to 80 stations)
Precise Point Positioning 1/2
• Attributed to Zumberge 1997 • Early commercial services (GPS);
• NavCom StarFire (C-Nav RTG) • Thales Geosolutions SkyFix-XP
• Vertical accuracy ~45cm (Bisnath et al. 2003)
• GLONASS (2009)
Precise Point Positioning 2/2
• 1986 STARFIX (John E. Chance & Assoc.) • 2001 Partnership with NavCom Technology Inc. • 2002 C-Nav RTG (Real-Time Gypsy) GPS • 2011 GPS/GLONASS (iCORE) • H < 10cm V < 15cm (95%)
C-Nav
Hydrographic Vertical Datums
• Datums • Global MSS
• DTU10 • CNES CLS 2011
• Local • VORF • BATHYELLI
BATHYELLI 1/2
• BATHYmetry with reference to the ELLIpsoid • Data Sets
Conventional Surveying
Credit: Ziebart, et al. VORF – The Vertical Offshore Reference Frame: Enabling Real-time Hydrographic Surveying
Surveying on the Ellipsoid
Credit: Ziebart, et al. VORF – The Vertical Offshore Reference Frame: Enabling Real-time Hydrographic Surveying
Testing Methodology 1/4
• Survey Vessel Haliotis
Testing Methodology 2/4
Testing Methodology 3/4
Testing Methodology 4/4
• Survey Area • Bay of Brest
Results 1/4
Results 3/4
Results 4/4
Conclusions
• PPP allows a stand-alone GNSS receiver to achieve centimetric positioning accuracy by utilising improved orbit and clock products
• BATHYELLI provides a link between CD and GNSS (GRS80)
• Real-time study (PPP / RTK / Tide Gauge) • PPP standard deviations <7cm
Future…….Death of RTK?
• Galileo, BeiDou, QZSS • Galileo CS on E6 • Triple-Frequency PPP (more combinations) • Local/Global Ionospheric & Tropospheric
corrections • Fractional Cycle Biases
Acknowledgements
GENAVIR is a Group of Economic Interest for the management of oceanonographic fleets
-GENAVIR operates : - Ifremer fleet : 8 vessels – 5 deep underwater systems (ROV, AUVs , deep tow …) - IRD fleet (2 vessels)
-320 people, including : - vessels crews (200) - engineers and technicians (70 in Toulon and Brest) for : - vessels and equipment maintenance - underwater systems operation and maintenance - scientific equipment operation - data quality assurance - navigation and QC software development
Questions?
Questions…….