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

BATHYELLI 2/2

http://data.shom.fr

• CD with respect to GRS80

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 2/4

http://refmar.shom.fr

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…….