Kongsberg EM 3002 Technical specifications

EM 3002
Multibeam echo sounder
Product Description

Kongsberg EM 3002
Multibeam echo sounder
Product description
855--164929 / Rev.A

Note
Kongsberg Maritime AS makes every effort to ensure that the information contained
within this document is correct. However, our equipment is continuously being
improved and updated, so we cannot assume liability for any errors which may occur.
Warning
The equipment to which this manual applies must only be used for the purpose for
which it was designed. Improper use or maintenance may cause damage to the
equipment or injury to personnel. The user must be familiar with the contents of the
appropriate manuals before attempting to install, operate or maintain the equipment.
Kongsberg Maritime AS disclaims any responsibility for damage or injury caused by
improper installation, use or maintenance of the equipment.
Copyright
E2004 Kongsberg Maritime AS
The information contained within this document remains the sole property of
Kongsberg Maritime AS. No part of this document may be copied or reproduced in any
form or by any means, and the information contained within is not to be communicated
to a third party, without the prior written consent of Kongsberg Maritime AS.
Contact information
Support: [email protected]
Sales: [email protected]
24 hrs support telephone: [phone]
Strandpromenaden 50
P.O.Box 111
N-3191 Horten,
Norway

EM 3002 / Base version
II 855-164929 / A
Table of contents
1SYSTEMOVERVIEW 1.....................................
Key facts 1...............................................
System characteristics 2.....................................
2PERFORMANCE 5..........................................
3 INSTALLATION 13..........................................
Introduction 13.............................................
Operator Station 13.........................................
Processing Unit 13..........................................
Sonar Head 13.............................................
4OPERATION 16..............................................
System control 16...........................................
Data logging 18............................................
5 POST-PROCESSING 19.....................................
Post-processing options 19....................................
Brief descriptions 19........................................
6 CUSTOMER SUPPORT 20....................................
Introduction 20.............................................
Installation 20..............................................
Documentation and training 20................................
Service 20.................................................
FEMME 21...............................................
Terms and conditions 21.....................................
7 SCOPE OF SUPPLY AND OPTIONS 22......................
Standard system 22.........................................
Options 22................................................
System integration 22........................................
8 TECHNICAL SPECIFICATIONS 24..........................
Overall specifications per Sonar Head 24........................
Interfaces 24...............................................
Physical specifications 25....................................
Environmental and EMC specifications 26.......................

Product description
III
855-164929 / A
Document logistics
Rev Date Written Checked Approved
A11.03.04 EHa FP KN
B
C
D
E
F
G
(The original signatures are recorded in the company’s logistic database.)
Rev Comments
AOriginal issue.
B
C
D

Product description
1
855-164929 / A
1SYSTEMOVERVIEW
Key facts
The Kongsberg EM 3002 multibeam echo sounder is a very
high resolution seabed mapping and inspection system meeting
the most demanding standards for survey accuracy. The
minimum operating depth is from less than 1 m below its
transducers, and in typical sea water conditions the system
operates to more than 150 m depth (less in warm water and
more in fresh water). Small dimensions and low weight makes
the system portable and easy to install. This allows use on
survey launches and subsea vehicles to 1500 m water depth.
The EM 3002 system has a very high ping rate of up to 40 Hz, a
large number of measurements per ping (up to 254 per sonar
head), 1.5°beamwidth, and electronic pitch and roll
stabilization. 100% coverage of the bottom is achievable at
vessel speeds of about 10 knots in shallow waters with
acrosstrack coverage of up to four times depth with a basic
system. At larger depths the achievable coverage may be up to
200 m, and then 100% coverage is achievable with vessel
speeds up to 20 knots.
The EM 3002 may be configured to use two sets of transducers
(Sonar Heads). This increases the shallow water coverage to up
to ten times the depth, and the number of measurements per
ping up to 508. With an angular coverage sector of nominally
200°(with the heads tilted 40° to each side) the dual system also
allows surveying to the water surface along shorelines, river
banks and man-made structures.
The EM 3002 beamspacing may be set to equiangular or
equidistant. The beams are electronically roll stabilized. The
coverage may be limited by the operator either in angle or in
swath width without reducing the number of beams. In the near
field dynamic focussing is employed. A combination of phase
and amplitude bottom detection algorithm is used, resulting in a
measurement accuracy of 5 cm RMS being achievable.
The system sonar frequency is nominally 300 kHz allowing
small dimensions, good range capability and high tolerance to
turbid waters. The transmit fan may be widened as an aid to
target detection. Integrated seabed acoustical imaging capability
is included as standard. Options include display and logging of
beamformed water column data and of raw stave data (before
beamforming).

EM 3002 / Base version
2855-164929 / A
The EM 3002 can be delivered either as a basic multibeam echo
sounder instrument for system integration, or as a complete
stand-alone seabed mapping system. The Operator Station, a
high-performance PC workstation, will always include the
necessary operator controls for setting and running the system,
data logging, and system testing. Normally the Operator Station
also includes an extensive set of graphical displays for data
quality control, but third-party software may instead be installed
for this purpose.
Postprocessing software for the EM 3002 is available from both
Kongsberg and third-party suppliers. A world-wide marketing
and service organization having many years of multibeam
experience is available for supporting the EM 3002.
→A system overview is shown in figure 1.
→Data example is shown in figure 9 on page 18.
System characteristics
Main units
The basic Kongsberg EM 3002 multibeam echo sounder
consists of three (or four) units:
•Sonar Head(s)
•Processing Unit
•Operator Station
The system may be delivered either with one sonar head (EM
3002S) or with two sonar heads (EM 3002D).The dual sonar
heads can be arranged in different ways. The most common
configuration is to mount the two sonar heads tilted about 40
degrees to port and starboard in order to obtain a wider swath
coverage.
A complete mapping system will in addition include a vessel
motion sensor, heading sensor, sound speed sensor and a
positioning system. For ROV applications a telemetry system is
required for data communication between subsea units and
surface electronics.
Sonar Head
The EM 3002 Sonar Head contains the transducers and all
transmitter and receiver electronics. The diameter of the Sonar
Head is 332 mm and it’s height 119 mm. The sonar head
material is titanium, making the unit robust, durable and 100%
non-corrosive. The transducers are replaceable in the event of
damage for example due to grounding.

Product description
3
855-164929 / A
The maximum deployment depth for the standard sonar head is
500 m. A sonar head is available for maximum 1500 m water
depth.
A single cable with an underwater plug connects the Sonar Head
to the EM 3002 Processing Unit. The cable is normally 15 m
long, optionally up to 45 m.
Existing EM 3000 sonar heads may be used in an EM 3002, but
a factory check-up is recommended.
Processing Unit
The EM 3002 Processing Unit performs the beamforming and
bottom detection. It further controls the sonar head with respect
to gain, ping rate, pitch compensation of the transmit fan and
roll compensation of the receive beams. It contains all interfaces
for time-critical external sensors such as vessel attitude (roll,
pitch, heading and heave), vessel position and external clock.
The Processing Unit is contained in an instrument case prepared
for mounting in a 19” rack (height 4U). All circuit boards are
plugable into a cPCI bus backplane giving a very robust
solution. Ethernet is used for data communication with the
Operator Station.
Operator Station
The Operator Station of the EM 3002 is the HWS 10 high
performance PC workstation with Kongsberg SIS software.
Additional third-party sw may be installed. The HWS 10 is dual
bootable to either Linux® or Microsoft Windows XP®.
Software for controlling the EM 3002 installation and runtime
parameters, data logging and running selftest on the system is
always included as standard.
The HWS 10 is normally supplied with a 17.4” industrial LCD
monitor with a resolution of 1240x1024 pixels. Support for a
second monitor is included. A spill-proof US keyboard and a
standard optical mouse is normally supplied, but optionally a
small IP 65 rated keyboard with integrated track stick can be
delivered.

EM 3002 / Base version
4855-164929 / A
Figure 1 EM 3002 System overview
(CD21510)
Storage
media
Processing Unit
Optional, may also be
connected to the ship's ethernet.
Interfaces:
Sound Speed Sensor
Tide
Center depth output
Ethernet
Internal
Ethernet
Serial interfaces:
Special interfaces:
Supply voltage:
Positioning systems
Attitude (roll, pitch and heave)
Heading
Clock
Trigger input/output
Clock synchronization
115 or 230 Vac 50/60 Hz
Sonar Head Second Sonar Head
(optional)
Operator
Station

Product description
5
855-164929 / A
2PERFORMANCE
The operating frequency of the Kongsberg EM 3002 multibeam
echo sounder is 300 kHz. This frequency has been chosen
carefully to achieve an optimum balance between small
dimensions, narrow beams, and good range capability even in
turbid waters. Acoustical interference between the two sonar
heads of EM 3002D is eliminated by using two different
operating frequencies (293 and 307 kHz).
The beamwidth is 1.5°both on transmit and receive. The
transmit fan may be electronically stabilized for pitch to always
point vertically. The receive beams are electronically stabilized
for roll. Roll, pitch, heading, heave and the applied stabilization
are fully taken into account when calculating sounding depths
and positions. In the near field the receive beams are
dynamically focused to maintain angular resolution even at very
short ranges. All beamforming is rigorously done with a time
delay algorithm.
There are 160 simultaneous receive beams for each Sonar Head.
They are either spaced in an equiangular or equidistant pattern
within the coverage specified by the operator. There is also a
high density mode where 254 soundings are acquired per head
and ping. The additional soundings are derived by using smaller
sections of the range window than what the beamwidth
provides, thus reducing the effective receive beamwidth to
minimize the interdependency of the extra soundings.
Each Sonar Head has an angular coverage of 130 degrees
corresponding to a swath width of 4 times water depth. For an
EM 3002D system with two tilted Sonar Heads a total effective
swath coverage of up to 10 times water depth with up to the
water’s edge is obtainable even if the vessel is rolling. A dual
head system may also be used for profiling of say a trench or a
pipeline from two sides simultaneously. The number of
simultaneous receive beams is then doubled to a maximum of
508 with the high density mode.
The dense beam pattern together with the high ping rate of up to
40 pings per second gives a very dense sounding spacing. A
vessel speed of 10 knots in shallow waters and even more in
deeper waters is thus possible while maintaining 100% bottom
coverage.

EM 3002 / Base version
6855-164929 / A
The EM 3002 system depth accuracy is very good due to the
narrow beams and high range sampling rate used (14 kHz), but
most importantly through using the advanced bottom detection
methods which have been developed through long experience in
this field. Near normal incidence a centre of gravity amplitude
detection principle is employed, but for most of the beams the
system uses phase detection. This principle is based upon
splitting the receiving aperture for each beam in two sections,
and obtaining the angle of arrival of the incoming return signal
from the bottom by processing of the phase angles of the two
signals obtained. For every range sample a measurement of the
angle of arrival of the returned bottom echo is done, and from
all the bottom returns inside a receive beam the exact range to
the bottom in the beam’s geometrical centre is derived. The
combination of beamforming and phase processing is robust and
generates high quality sounding data.
The receive beamwidth of the EM 3002 varies inversely with
the cosine of the beam pointing angle referred to the Sonar Head
face. The resulting beam broadening for large beam pointing
angles does not have any effect on accuracy due to the phase
detection algorithm used in the EM 3002. Resolution is neither
affected, as it is dependent upon the alongtrack beamwidth and
the range sampling rate which do not vary.
The following figures show the expected instrumental accuracy
of the EM 3002. Note that the total system error will always be
higher than the instrumental error of the multibeam echo
sounder, because errors in the sensors measuring the vessel’s
motion, heading, and position, water level and water column
sound speed will contribute, as well as natural variations of the
sound speed both in time and space.
→Refer to figure 3 on page 9.
With high quality external sensors it has been demonstrated that
a mean system accuracy approaching 5 cm RMS is achievable in
shallow waters with the EM 3002. This accuracy is well within
the requirements of the IHO S-44 standard (4th edition) for
special order surveys. It has also been demonstrated that the EM
3002 will meet the same standard’s object detection
requirements, although for deeper waters some limitations in
vessel speed or coverage may be necessary.

Product description
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The acrosstrack sounding density will limit the usability of the
outer beams in a multibeam echo sounder, unless the beam
spacing is equidistant and the beam pointing angles are roll
compensated, which is the case for the EM 3002. It is common
practice to run a survey with overlap between the neighbouring
lines for quality control purposes. For a high resolution survey it
is recommended that the spacing between neighbouring survey
lines for EM 3002 is limited to about 3 times water depth and at
least twice that with the EM 3002D. These line spacing
recommendations will give an excellent sounding density and
also a good swath overlap between neighbouring lines.
At high frequencies the range performance of any sonar system
is strongly dependent upon water temperature and salinity in
addition to bottom reflectivity.
→Refer to figure 2.
(CD3209)
Figure 2 Attenuation in water surface. The depth dependence is
negligible except for the temperature reduction with increasing
depth.
The next three figures show the achievable swath width for
different absorption coefficients and bottom types as a function
of depth beneath the transducers for both single and dual head
versions.

EM 3002 / Base version
8855-164929 / A
For deeper waters these curves may be used to decide coverage
capability and hence the line spacing to be used in a particular
survey.
→Refer to figures 4 (page 10), 5 and 6
The performance of the EM 3002 will usually not be affected by
suspended particles in the water column (turbidness), which
would have been the case if its sonar frequency had been much
higher. Only heavy concentrations of large particles such as sand
(>50 mg/l for particle diameters of about 100 µm) or of very
fine particles (>100 mg/l for particle diameters of about 3 µm)
will lead to less achievable range in the outer beams than
predicted by the enclosed coverage diagrams.

Product description
9
855-164929 / A
Figure 3 EM 3002 theoretically calculated accuracy
(Cd21512)

EM 3002 / Base version
10 855-164929 / A
Figure 4 Calculated EM 3002 Coverage at 20 dB/km
(Cd21513)

Product description
11
855-164929 / A
Figure 5 Calculated EM 3002 Coverage at 65 dB/km
(Cd21514)

EM 3002 / Base version
12 855-164929 / A
Figure 6 Calculated EM 3002 Coverage at 135 dB/km
(Cd21515)

Product description
13
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3 INSTALLATION
Introduction
The compactness of the Kongsberg EM 3002 multibeam echo
sounder is a guarantee for a fast and easy installation. For a
surface vessel, the Operator Station and Processing Unit are
placed inside the vessel while the Sonar Head is mounted so that
it is always submerged in water with a mounting angle in
accordance to the system mission.
Operator Station
The Operator Station is a ruggedized PC workstation, prepared
for mounting in a standard 19” rack (requires 4 rack height
units). It is supplied with a rackable 17.4” industrial LCD
monitor, a keyboard and an optical mouse. A bracket for the
monitor is included for table top, bulkhead and roof mounting.
Processing Unit
The Processing Unit may be mounted in a standard 19” rack
(requires 4 rack height units).
On large vessels the Processing Unit may have to be mounted in
a different location closer to the Sonar Head due to the restricted
length of the cable connecting the two units (15 m standard
length extendable to a maximum of 45 m) or a fibre optic link
may be used.
Solutions for mounting the Processing Unit in an underwater
vehicle may be discussed.
Sonar Head
The EM 3002 Sonar Head must be mounted so that it has a clear
view of the bottom, i.e. no obstructions are permitted within a
sector of minimum ±75° acrosstrack and ± 30° along track with
respect to the face of the Sonar Head as seen from the
transducers.
For standard mapping purposes the Sonar Head should be
aligned with the keel line, and not be tilted more than about 10°
forwards or 40° to the side.
It is important that the Sonar Head is mounted so that the water
in front of the head is not aereated. On most vessels a suitable
location would be near the keel in the forward part of the vessel.
An arrangement for streamlining or mechanically protecting the
head may be added, but would normally not be required. Flush
mounting in a well may be used for a permanent installation.

EM 3002 / Base version
14 855-164929 / A
To lessen risk of damage to the Sonar Head in case of
grounding, it may be mounted on the side of the vessel above
the keel line. If the keel obstructs the view to one side, the head
may be tilted to the opposite side. ”Ice knives” may also be
mounted in front of the head for protection against floating
debris.
In a dual head installation the two sonar heads may be placed on
each side of the keel and tilted about 30-40° above the
horizontal, thus increasing the swath width to both sides. 40° tilt
would be best for shallow waters and surveying to the water’s
edge while 30° would increase maximum depth capability
somewhat.
Figure 7 Sonar Head installation example:
Retractable dual head