This document summarizes Fugro's G2+ worldwide centimetre-level positioning service. It discusses the history of Fugro's positioning capabilities from 1974 to present, including the introduction of G2+ in 2015. G2+ uses precise satellite orbit and clock data with integer ambiguity resolution to provide centimetre-level positioning accuracy globally in real-time. Static and dynamic testing shows G2+ achieves 95% horizontal accuracy of 3.5 cm and vertical accuracy of 8 cm. G2+ is being used for offshore applications like tide measurement, platform monitoring, and unmanned vessel navigation.

1. Fugro’s G2+ worldwide centimetre-level positioning service
Matthew Goode, Fugro Intersite B.V.
Offshore Energy 2015, 14 October 2015, Amsterdam, Netherlands

2. www.fugro.com2
History of positioning within Fugro
1974 1986
1996
2001
1984
Starfix positioning
system
Transit system
first used
Satellite based
DGPS
High frequency DGPS
service
HP dual-frequency
service

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History of positioning within Fugro
2006 2014
20152009
G4 multi-constellation
PPP service
G2+ ambiguity-fixed
PPP service
G2 GPS & GLONASS
PPP service
XP precise point
positioning (PPP) service

4. www.fugro.com4
 Orbit and clock corrections for GPS, GLONASS, BeiDou and Galileo
 Improved availability and reliability
 Galileo corrections available when Initial Operational Capability
(IOC) announced by the European Union
Starfix.G4

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 Uses dual frequency code and
carrier phase measurements.
 Considering the listed parameters:
 Precise satellite position known
 Precise satellite clock known
 Unknown receiver position of
most interest
 Integer ambiguity for carrier phase
measurements cannot be
separated from the hardware
biases, so estimated as lumped
real valued parameter.
 Fixing ambiguity to an integer
would give cm-level accuracy.
Standard PPP

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GNSS orbit and clock corrections

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Standard PPP approach
Precise orbits and
clocks
GNSS
measurements
PPP engine
Position

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 Satellite biases common for all
receivers in a network.
 Estimate satellite biases using
reference station network and supply
this to the user.
 Single differencing using a reference
satellite removes receiver biases.
 Remaining estimated ambiguity has
an integer nature.
 Attempt to fix to the correct integer
value for cm-level accuracy.
 Ability to fix ambiguities to integer
value is dependent on observation
conditions.
PPP with integer ambiguity resolution

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G2+ reference station network

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PPP-IAR approach
Precise orbits and
clocks
GNSS
measurements
PPP engine
Ambiguities
fixed?
Ambiguity fixed
position
Ambiguity float
position
Yes No
Hardware
biases
Ionosphere
Troposphere
(optional)

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Static results

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Static results: local comparison
 StarPack receivers located at
Fugro reference stations.
 Starfix.G2+ real-time orbit, clock
and hardware bias corrections
received through L-band link.
 Identical set-up as used in the
field.
 95% accuracy of 3.5 cm in
horizontal and 8 cm in vertical
achieved.

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Static results: Bergen, Norway

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Static results: Bergen, Norway

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Static results: Great Yarmouth, United Kingdom

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Static results: Great Yarmouth, United Kingdom

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Static results: Houston, TX, USA

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Static results: Houston, TX, USA

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Static results: Leidschendam, The Netherlands

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Static results: Leidschendam, The Netherlands

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Static results: Starfix.G2 vs Starfix.G2+
Values above the Starfix.G2+ bars show the percentage improvement compared to Starfix.G2

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Static results: global comparison
 Global distribution of 101 sites
 Comparison between Starfix.G2 and Starfix.G2+ solutions
 Comparison of global sites for one day
 Comparison of one site over 8 days

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Static results: 7 October 2015, 101 sites

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Static results: 8 days, Perth, Australia

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Static results: 8 days, Istanbul, Turkey

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Static results: 8 days, Romoland, CA, USA

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Dynamic
results

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Gulf of Mexico test bed

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Gulf of Mexico test bed

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 Dynamic environment with
real-time solution.
 Two antennae mounted on a
fixed surface with known
distance.
 Two StarPack receivers using
common source of G2+
corrections (hardware biases).
 Difference in north, east and up
components calculated.
Comparison between different sources of hardware delay
G2+
corrections
G2+
Solution
(172)
G2+
Solution
(175)
Vector
calculated
172 175

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Vessel configuration
175172
175 172

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Baseline comparison

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Offshore
Applications

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Offshore Applications: real-time tide measurement

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Offshore Applications: buoy height dynamics

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Offshore Applications: real-time platform monitoring

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Offshore Applications: Unmanned vessels
Source: Rolls-Royce Holdings/Bloomberg

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 Global real-time positioning with a
95% accuracy of 3.5 cm in
horizontal and 8 cm in height.
 Tailored for the offshore market.
 Successfully tested in dynamic
environments.
 Already in use by Fugro
customers.
Conclusions

39. Matthew Goode
GNSS R&D Team
Geodesist
Fugro Intersite B.V.
Dillenburgsingel 69
Leidschendam 2263 HW
The Netherlands
M.Goode@fugro.nl