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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
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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, ...