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Long Range Kinematic for Marine Surveying – Latest State of the Art

Olivier Casabianca

Benelux Hydrographic Society Workshop 7 May 2008

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Hydrography & Bathymetry

Dredging & Coastal Works

Offshore Production(Oil & Gas, Drill

Positioning, Laying Cable)

Seismic & Offshore Surveys

CoastalReference Station

LRK® Long Range Kinematic: Where?

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LRK® Long Range Kinematic: Field Definition

The distance between the base and the rover

Fixed or moving base (so called relative positioning)

The means of communication

The disparity between receiver brands

Accurate Baseline Determination whatever…

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LRK® Long Range Kinematic: Engineering Definition

LRK® is a type of cooking:

Try a little bit of salt, then a little bit of pepper…

Test the result…

Add or remove extra salt or pepper (not so easy )…

Add something else…

Validate each ingredient with a HUGE amount of data…

Always make statistical validation…

Move step by step to achieve the performance…

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LRK® Long Range Kinematic: The Ingredients?

LRK® is the application used when you must account for each available piece of information and cook it properly…

Typical ingredients can be: Proper usage of antenna phase variation corrections Proper usage and tuning of troposphere models Proper usage and tuning of ionosphere models

These parameters do not bring much to short range RTK, but each of them is key when looking at LRK® performance.

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LRK® Long Range Kinematic: the Key Components…

1. A Rover with a powerful PVT engine

2. A Base: single Base or Network

3. A data exchange between Base and Rover

4. A means of communication between Base and Rover

Radio

Cellular Modem (GSM / GPRS / Edge / UMTS / CDMA…)

Cable (tail buoy positioning along a seismic streamer, why not !)

The 4 main components that are part of Long Range Kinematic are:

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Trends and Customer Needs

Customers are looking for:

Accuracy

Availability

Reliability/Quality

Benefits from Network development

Benefits from new GNSS signals (GLONASS, L2C…)

Cross compatibility between GNSS product from different manufacturers

RTK cm accuracy

Reliability/Quality

Network

Future ready

Availability

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It is the Right Time for GLONASS

When number of GLONASS satellites < 10, there is little improvement from GLONASS

Each satellite after 10 provides clear improvement

When number of GLONASS satellites > 15, GLONASS provides strong improvement worldwide

GLONASS Satellites: History and Prediction

26

22

16

1312

11

78

10 10

14 14

11

18

21

24

0

5

10

15

20

25

30

Year

Nu

mb

er

Ashtech Launches 1st GPS+GLONASS

Receiver, GG SurveyorMagellan Launches New

GPS+GLONASS

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Magellan Professional’s answer:

New Core Technology GPS/GLONASS L1/L2, up to 75 channels

New High-End Land Survey product: ProMark 500

Coming soon - Marine Sensor …

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The PVT Engine: Introducing BLADE

BLADE™ is a universal and powerful GNSS RTK engine, which equally well supports:

Conventional RTK mode, i.e. against a single static base.

Advanced RTK modes:

Heading function,

Against moving base,

Advanced solutions using SBAS and GLONASS,

Using third party Net corrections: BLADE™ provides extensive compatibility with other manufacturer's GNSS products.

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Network Benefits?

0102030405060708090

100

fixed

in 3

00 s

ec,

%

10 53 57 59 76 102 113

data set (baseline, km)

Availability w/ and w/o Network corrections complete RTK reset

Master only

Master+Network

050

100150200250300

time

to fi

x in

50

%, s

ec

10 53 57 59 76 102 113

data set (baseline, km)

50% TTFF w/ and w/o Network corrections complete RTK reset

Master only

Master+Network

“MASTER”:RTCM-3

Messages 1004,1006,1008

“MASTER+Network”:Additional RTCM-3

Messages 1014-1016 (Master-Auxiliary

corrections)

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LRK® Long Range Kinematic & BLADE

BLADE insures good performances for long baselines (single base solution)

BLADE insures also noticeable TTFF performance improvement thanks to Network corrections compared to single base solution for baselines up to 100 km.

BLADE

100 Km

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Performance is potentially the same with either static or moving base

However, a moving base usually experiences worse GNSS tracking, more frequent carrier cycle slips and loss of lock compared to a static base.

As a result, actual performance of an RTK rover working with a moving base may degrade because of poorer data quality coming from this moving base.

ΔX, ΔY, ΔZ

LRK® with Moving Base… Performance?

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The Base and the Means of Communication

1. Single Base with point-to-point or point-to-multipoint capabilities

UHF radio… point to multipoint

Cellular Modem… point to point (GSM/CSD)

Cellular Modem… point to multipoint (GPRS…): can be part of a local or global Network

2. Network:

Accessible via Internet (modem)

Gives access to multiple single base stations

Provides complementary information depending of the network type (VRS, FKP, MAC…)

Simplification of the set-up… no need to manage Base installation and maintenance for the customer

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Radio vs. Modem

UHF radio:

Needs frequency allocation.

No user fee.

Point to Multipoint.

Baseline limitations due to the technology… Magellan UHF technology is one of the most powerful in the market place.

Modem:

Where a “communication network” is available(coastal works / inshore navigation).

Has user fees.

Potentially “no” Baseline limitations depending on the PVT engine capabilities…

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Use Cases and References…

Use Cases and References…

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Salvage of MV Tricolor Using LRK® GPS

 

190m long – 32 m wide Vehicle carrier

Sank in middle of Channel

Danger to shipping & environment

Very accurate positioning Drilling position & orientation Lifting equipment 9 pieces of 2000-3000 tonnes

LRK station at 42km

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Longueuil

Verchères

Sorel

Grondine

PortneufNeuville

St-François

Montmagny

Pointe du Lac

Sainte-Marthe

Montréal

Québec

Répétitrice

Station OTF

Chenal Dragué

LRK Hydrographic Survey in Canada

300 km

6 LRK Stations

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LRK Dredging & Coastal works in China

What?

$1 Billion project - 8 years

Channel deepening 8.5 to 12.5 m

100 km dykes construction

80 km dredged channels

How?

5 reference stations

50 RTK mobile units

Not only GPS

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References

Survey / Bathymetry Numerous Port Authorities, Dutch Ministry of Transport, SHOM, Canadian

Coast Guards, ...

Dredging / Coastal works Boskalis, Jan De Nul, Dredging International, Van Oord, Great Lakes, ...

Offshore Works Veripos, Subsea7, Fugro-Topnav, Technip / Coflexip, Stolt, ...

Seismic / Offshore surveys CGG, Subsea7, ...

Coastal Reference Stations US Coast Guard, Canadian Coast Guard, Phares & Balises Rijkswaterstaat, Korean Maritime Affairs & Fisheries, ...

Others Various national civilian / military authorities: India, China, Chile, ...