1 © kongsberg november 30, 2015 the evolution of the kongsberg simrad multibeam echo sounders by...
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1© KONGSBERG April 22, 2023
The Evolution of the Kongsberg Simrad Multibeam Echo Sounders
by
Dr. Freddy Pøhner
2© KONGSBERG April 22, 2023
KONGSBERG main business areas
Defence & AerospaceMaritime
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Kongsberg Maritime
Divisions
Human Resources/Administration: Finn H KristensenQuality Management: Finn H KristensenIS/IT systems: Steinar AabelvikCommunication: Gunvor H Midtbø
Human Resources/Administration: Finn H KristensenQuality Management: Finn H KristensenIS/IT systems: Steinar AabelvikCommunication: Gunvor H Midtbø
Business Support
Torfinn KildalPresident
Steinar AabelvikCFO
Torfinn KildalPresident
Steinar AabelvikCFO
Sales & MarketingTor Erik Sørensen
Sales & MarketingTor Erik Sørensen
Dynamic Positioning& Navigation
Ole Gunnar Hvamb
Dynamic Positioning& Navigation
Ole Gunnar Hvamb
Process AutomationNils E Standal
Process AutomationNils E Standal
Marine AutomationLars Gørvell-Dahll
Marine AutomationLars Gørvell-Dahll
Satellite Positioning & AIS
Bjørn Fossum
Satellite Positioning & AIS
Bjørn Fossum
HydroacousticsRolf Arne Klepaker
HydroacousticsRolf Arne Klepaker
Marine ITBjørn T Frøshaug
Marine ITBjørn T Frøshaug
Marine ElectronicsJan E Berner
Marine ElectronicsJan E Berner
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We participate where the action is
Global presence• HEAD OFFICE
• OFFICES
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n
Kongsberg Maritime premises in Horten, Norway
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n
M/K Echo, a 30 m vessel for test and demonstrations
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“Pingeline”, a 32 feet hydrographic launch, for testing
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Kongsberg transducer test tank with EM 1002 transducer being tested
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Testing of a Multibeam Echo Sounder System
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In-door test tank: 10 x 6 x 6 meters
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Hydrographic Applications
Multibeam Echo Sounders
Single Beam Echo Sounders
Sub Bottom Profiler
Marine Data Management
Operation Support:Cable Laying
Nautical charting
Route Surveying Operation Support:Dredging
Port and HarbourSurveying
Mapping of Riversand Canals
Marine Geology Scientific research Habitat mapping
Exclusive EconomicZones mapping (EEZ)
Detailed Mapping(ROV, AUV applications
Mapping of Riversand Canals
Processing software
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Launching sequence of multibeam models
time
1990 1995 2000 2005
EM 1
00EM
1000+
EM
12
EM
121
EM
3000
EM
300
EM
120+
EM
2000
EM
3002
EM
710
SBP 1
20
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How well does the terrain model represent the seabed terrain?
The Quality of a sounding process(1):
Seabed mapping process
Sounding process (on ship) Data processing
Echosounder
PositioningMotion compensation
Sound velmodeling
Seabed Terrain Terrain model
= ? =
Plotter WorkstationColour PostscriptPrinter
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The terrain model is a mathematical surfaceThe terrain model is a mathematical surfacebased upon a set of depth soundingsbased upon a set of depth soundings
The best terrain model is obtained by:
A. Precise depth soundingsB. Smallest possible acoustic footprint for each soundingC. Precise positioning of each soundingD. High density of soundingsE. Even spacing between soundings
The Quality of a sounding process(2):
These principles have been and still are the guidelines for most of our developments
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Acoustic principles developments
1986/EM 100: Basic properties of the Simrad multibeams:
Phase + amplitude bottom detector
Automatic gain steering and bottom tracking
Split beam phase
Fullbeam
amplitude
Phase Detect
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Snell’s law of refraction: sin(Ai)/Ci=constant
C1
C2
C3
C4
A1A2
A3
A4
Refraction of Acoustic Beams
All models have had built-in real time compensation.Early models used lookuptable + interpolation,accurate realtime calculation since 1997.
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Multibeams interface MVP’s, no interruption of sounding whena new profile is entered (due to realtime calculation of refraction)
Moving vessel profilers: Frequent sampling of sound velocity profiles
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The Mills Cross array was introduced with EM 12 in 1990
Transducer arrayconfiguration
Tra
nsm
it
Receive
Forwarddirectionon shipTransmit beam
Receive beamEffective beam footprint
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Transmit in sectors, and use different frequencies
Requires a larger transducer+ direct steering of all transducer elements in 2 dimensions
Transmission process: FRDT principle
This was introduced with EM 12 in 1990.
Advantages:
Higher source level (=increased range)+reduced problems with sidelobes from the specular return.
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Beam spacing
Equiangle
Equidistant
In-between
EM 1002 beamangles
-80.00
-60.00
-40.00
-20.00
0.00
20.00
40.00
60.00
80.00
1 11
21
31
41
51
61
71
81
91
101
111
Beam number
Beam
an
gle
equiangle
equidist
inbetween
Equi- distant beam spacing was introduced as an improvement to the EM 12 + EM 1000 in the early 1990’s
Equi-distant beamspacing
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Equidistant beamspacing
Improved sounding density in the outer part of the swath
Example at 10m depth
crosstrack beam spacing
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
Angle
5.00
15.0
025
.00
35.0
045
.00
55.0
065
.00
beam angle
cro
sstr
ack
dis
tan
ce
beam spacing EM3002
beam spacing Reson8125
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Manual ModeSector fixed to operator set angles
Sector Coverage
Auto ModeSector limited by:•Max angle set by operator•Max coverage (deg) set by operator•Signal to Noise Ratio
Adapting the system to varying depths and bottom conditions
Introduced early 1990’s
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Rang
e Re
solu
tion
cell
Beam
2 different Data Sets are derived:
A. Beam Intensity=Mean Backscatter Strength over the Footprint
B. Sonar Image Data= All the individual Backscatter values
Acoustic Footprint of Beam
Beamformed seabed imagery (Snippets)
This was introduced in 1990 for EM 12 and EM 1000
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EM 12D - Surveyed by IFREMER
Bathymetry and Sonar Image combined in 3D
Ifremer pioneered the development of software to processSeabed imagery
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Data courtesy of C & C Technologies Inc.
EM 300 (30 kHz) Multibeam Bathymetry & Backscatter
Bathymetry & Imagery
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DualSingle
1995/96: EM 3000 was introduced
This step was made possible by availability of more compactelectronics. A sonar head has a mills cross transducer array + 2electronic boards: 1 for transmission and 1 for reception.
CHS was the first client.
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Co-ordinate transformations and modelling of
transmission through water Ar=Beam angle rel. transducer
T=2way travel timeH
eave
Roll
Pit
ch
Tra
nsd
ucer
mou
nti
ng
pos +
an
gle
s
Su
rface s
ou
nd
vel.
Sou
nd
vel.
pro
file
Sounding depth (z)
Rel. pos. of sounding (x,y)
Calculation of Depth Data
Exact algorithm was introduced for EM 3000 in 1995, allowed for free mounting angles of sonar heads
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Test arrangement for they German Waterways Authority
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Accuracy as function of swath width
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Construction Drawing
Survey Result
Test Result from a Lock
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Stabilization for pitching is obtained by steering the transmit beamelectronically forward or aft at the time of transmission, based upon input from the motion sensor.
Pitch Stabilisation
Introduced from 1990
A multielement transmit array is required, + several steerable transmitters
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The effect of pitch stabilisationThe effect of pitch stabilisation
Sounding patterns on the bottom
Competitor result,Without pitch stabilisation
EM 3002 result
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Each Receive Beam is stabilized for roll by the Beamformer, using input in real time from the Motion Sensor. All beam pointing angles are thus constant, related to the vertical axis.
The roll angles will be different for the different beams
Roll Stabilization
Since 1986
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The effect of roll stabilised beams
Stabilized:The swath is notinfluenced by rollmovements
Unstabilized:The swath is rolling sideways, and the effectiveswath is then reduced.
EffectiveSwath
Unstabilized swath
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Compensating for vessel yaw movements
Fulll compensation for pitch and yaw
1000m
0
2000m
1000m
-1000m
0
No compensation
0
2000m
1000m
-1000m
(As EM 120)
Calculation of sounding pattern on bottom
Ship speed: 10 knotsDepth: 3000mPitch: +/-5 degrees, 15sec periodYaw: +/-6 degrees, 200sec period
Pitch compensation only2000m
1000m
-1000m
0
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EM 120 and EM 300 Multibeam echo sounders
With Yaw stabilisation
Without Yaw stabilisation
Calculated by UNB, Canada
From 1997
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MBE sounding errors
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0 10 20 30 40 50 60 70
Swath angle
Std
de
via
tio
n o
f s
ou
nd
ing
s
EM 120 1x2
Seabeam 2112
EM 12D
System accuracy improves over time
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P1
P2
Kongsberg develops its own ASIC’s and HYBRID circuitsfor the sonar front-end boards
TRB 32 Transmit/Receive Board for 32 channels
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Plugs for connection totransducerelements Backplane
P1
Backplane P2
Transmitterhybridcircuits
Each transmitter is a special purpose HYBRID circuit
64 channel transmitter board
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EM 1002 Optional Retractable Hull Unit
The hull unit provides:- Transducer protection during transit- Good acoustic conditions when extended- Active pitch compensation of beams
It is mounted on a cylindrical trunk which is welded to the ship’s hull
Max survey speed with Hull Unit is 10 knots
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“Kilo Moana” - EM 1002 transducer being fitted
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Transducer Gondola
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Ice breaker solutions
Titanium plates for light protection against ice was introduced in 1990.Ice breaker solutions have been developed since, for 12 and 30kHz
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EM 3000D Bow Installation
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Near Field
L Beam-width
The acoustic near-field – Beam focussing
Without focussing:Inside the near field the beam is as wide as the physical size of thetransducer
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Beam focusing
Near Field
LBeam-width
Dynamic focusing: The focus point is shifted as function of time/range
Foca
l poin
t
Introduced from 2004
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Beam focusing of transmit beams
Focus rangeright sector
Focusing in the nearfield on transmit is feasible by using three separate transmit sectors per ping
Footprintalongtrack
Focus rangeleft sector
Focus rangecentral sector
From 2005
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Monitoring
Control
Depth Profile
Geographic window
Beam Intensity/Quality
Waterfall
By choosing AUTO for parameters, the system will adapt to changing depth
The Human Interface (MERLIN - Unix)
1995-2004
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Operators Display (SIS- Windows or Linux)
Signal strength
Depth profile
3D (waterfall)
Watercolumn(beamformed)
Seabed Imagery
Gridded terrain model: 2D or 3D
Raw hydrophonedata
2004--
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Raw data recorder
The raw data recorder is mounted on the side of thetransceiver cabinet.
Introduced approx. 1999Only stave data is recorded
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Processed result from raw data recorder
Water column display processed from 1 ping with EM 300Courtesy of Xavier Lurton, Ifremer
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Beamformed raw data can now be recorded and post processed
EM 3002 Real time Water Column display - 2004
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Some recent improvements
Broad band transducers – composite ceramics
Use of FM sweep/chirp as transmit waveforms
High resolution beam processing
Multiple sounding profiles per ping
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Composite ceramics for wide bandwidth
EM 710Transmit
Transducer
30-50% bandwidthcan be obtained
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FM sweep/chirp transmit pulses
The use of FM sweep or chirp signals is being implemented on EM 710 as the first system
It requires new beamforming algorithms, pulse compression, and increased capacity for transmitting long pulses.
This is used to increase the energy content of the TX pulse.
A longer range can be obtained without sacrifice of resolution
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High resolution beam processing
In EM 3002 the number of soundings (254 per sonar head)
is higher than
the number of acoustic beams (160 per sonar head)
This is a technique to increase and improve the system resolution.
”Soft” beams in between the acoustic beams are generated to produce the extra soundings.
A special signal processing technique, high resolution beam processing,is used in order to reduce the acoustic footprint of each sounding, and produce soundings that are independent. The best horisontal system resolution is then approximately 20cm.
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The full number of beams is maintained also when the swath is reduced.
Full swathwidth Reduced swathwidth
254 soundings 254 soundings
This is a unique feature.If the swath width is reduced – on purpose or due to maxrange –the full number of soundings is still produced inside the active swath.
Result: A more dense pattern of soundings+ reduced footprint size of each sounding.
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Result example, 18m depth 120 degree swath
Data processing by QPS
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Result example, 18m depth 90 degree swath
The details are sharper!
Data processing by QPS
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Evolution of resolution
EM 12 1990: 1.8 x 3.5 deg
EM 121 1993: 1 x 1 deg
EM 3000 1995: 1.5 x 1.5 deg
EM 300/120 1997: 1 x 1 deg
EM 710 2005: 0.5 x 1 deg
The no. of soundings/ping and the ping rate is increasing due tomore computer power being available.
EM 3002D and EM 710 will both be able to produce close to 20.000 soundings per second.
© KONGSBERG April 22, 2023
Transmit beamReceive beamEffective beam footprint
Transmitbeamwidth
SBP 120 Multibeam Sub Bottom Profiler
Receivebeam width
EM 12012 kHz
SBP 1202.5-7kHz
Common receivearay
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SBP 120 block diagram
Frequency 2.5 – 7 kHzPulse forms: Chirp
CWRicker
Floating point receiver A/D
Arrays lengths:
8m - 3 degree beams 4m - 6 degree beams 2m – 12 degree beamsSub Bottom Profiler
Transmit transducer array
Operator Station
O ptional
Interfaces:Ethernet and
- Depth and bottom slopes- Navigation & Position ing -system s
Seria l lines:- Sound Velocity near Transducers/ Sound Speed Sensor
- C lock
Interfaces:- A ttitude (ro ll, p itch and heave)
InternalE thernet
-- 2x4
–
(CD
632
1)
SBP 120RX/TX Junction Box
Beamformer Unit
SBP 120Transceiver Unit
Hydrophone Signals
EM 120Transceiver Unit
EM 120 TX Trigger
EM 120
In ternalE thernet
Int.
Eth
ern
et
S ystem Trigger out
O ther external Trigger
Int.
Eth
ern
et
Tri
gg
er
in
Tri
gg
er
ou
t
(seria l line)
Contro l
EM 120Receive transducer array
-- 16
EM 120 PreamplifierUnit
EM 120
9
--
8
Remote On / Off
64© KONGSBERG April 22, 2023
SBP120 - 3°
Specular return / backscatter
Echogram Multiple beams
Smooth surface layer
Rough buried structure
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Image ~4.5km alongtrack,
~450 ms ~ 335 m from top to bottom
-> average slope along ~ - 4°
SBP 120-3°: Sloping terrain
Data © SHOM