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Simrad AS
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Box 111
N-3191 Horten
This chapter provides a brief introduction to the Simrad ES60
fishery echo sounder system.
Related topics
→Overview, page 2
→ES60 System drawing, page 3
→Wave propagation, page 4
→Bottom echo, page 6
→Split-beam operation, page 8
→Observation range, page 10
System description
Important notice
Windows NT, Windows 2000, Windows XP and Windows are
either registered trademarks or trademarks of Microsoft
Corporation in the United States and/or other countries.
Echosounder software version
This manual complies to echo sounder software version
1.5.0.75.
857-160970 / Rev.H
1
Simrad ES60
System overview
Key facts
The Simrad ES60 echo sounders is designed for the professional
fishery community implementing the latest innovations.
• The ES60 system is flexible and easy to configure due to the
modular design.
• Echo sounders ranging from relatively low-cost single beam
to large multi-frequency systems containing several
split-beam channels can be realised.
• Menus and dialogue boxes are operated by a standard mouse
or a roller ball.
• Large colour liquid crystal displays (LCD) are used. A
standard computer mouse may be used.
• The ES60 uses the Microsoft Windows® display interface.
Operation is to a large extent self-explanatory. Getting started
is easy if you are familiar with standard Microsoft
Windows® programs.
• A store/replay function reduces the need for echogram
printout on paper. The unprocessed transducer signal is
recorded on the internal harddisk. During replay, this signal
is injected into the ES60 processing software as if it arrived
directly from the transceiver.
Main units
The standard version of the ES60 echo sounder consists of the
following units:
• a display unit (several sizes are available)
• a Processing Unit (personal computer)
• a General Purpose Transceiver (different types are available)
• a transducer (a wide range of frequencies are available)
Up to four frequency channels can be installed in a single
system. High-power single-beam and split-beam transducers are
available at operating frequencies ranging from 12 to 200 kHz.
2
857-160970 / Rev.H
System description
A
System diagram:
(A) = LCD monitor
(B)=ProcessorUnit
(C) = General Purpose
Transceiver (GPT)
(D) = Transducer
D
B
C
(CD102000)
857-160970 / Rev.H
3
Simrad ES60
Wave propagation
The velocity of sound wave propagation in the sea varies
slightly with temperature, salinity and pressure. The velocity
varies between 1440 and 1520 m/s in shallow sea water, while a
velocity around 1480 m/s can be expected at 1000 m depth. In
shallow fresh water the velocity is approximately 1430 m/s.
A good average value to be used in the Environment dialogue
box is 1470 m/s.
Figure 1 The
wave propagation
principles
The ES60 transmits high energy sound wave pulses into the sea.
A flat bottom reflects the transmitted wave as if it were a mirror.
The propagating energy is spread over a larger and larger area as
it travels down to the bottom and up again. The energy is spread
over a four times larger area every time the travel distance
doubles.
A large school of fish reflects sound waves similarly. This type
of spreading is referred to as square-law or 20 log TVG (Time
Varying Gain) spreading.
The situation is slightly different when observing the echoes
from individual fish. The transmitted wave undergoes
square-law spreading when travelling from the surface and
down to the fish. The swim bladder of the fish scatters a small
fraction of the arriving energy in all directions. Travelling from
the fish and back towards the surface the scattered wave
undergoes another square-law spreading. The combined effect is
referred to as quad-law or 40 log TVG spreading.
In the echo sounder’s Echogram dialogue box 20 log TVG
spreading is called School Gain and Bottom Gain, while 40 logTVG spreading is called F i sh Gain.
4
857-160970 / Rev.H
System description
Propagation losses due to absorption are much higher in sea
water than in fresh water. Absorption also increases with
frequency. At 38 kHz the absorption is 0.5 dB/km in fresh water
and 10 dB/km in sea water. At 200 kHz the absorption is 10
dB/km in fresh water and 50 dB/km in salt water. The echo
sounder must know which water type is present in order to
compensate for these losses correctly.
(The dB (decibel) unit has long traditions in underwater
acoustics and other fields in physics. It is a logarithmic measure
for the ratio between two quantities).
Related topics
→Environment, page 89
→Echogram, page 85
857-160970 / Rev.H
5
Simrad ES60
Bottom echo
Figure 2
Bottom echo
A hard flat bottom reflects the transmitted signal as if it were a
mirror. The transmitted pulse hits the illuminated bottom area at
nearly the same instant, and the echo from different parts of this
area arrive back at the surface also at nearly the same instant.
The received echo signal is basically an attenuated copy of the
short transmit pulse. The echo signal from a sloped bottom is
characterised by having a longer duration and a slower rise and
fall time. The transmitted pulse first hits the slope at point A,
and as time elapses the reflection point travels along the slope
towards point B. Many locations do not have a solid hard
bottom. Frequently, the bottom is composed of layers of mud,
clay and sand which can be observed as coloured bands on the
echo sounder display.
The bottom detection algorithm is implemented solely in
software, and separate algorithms are run for each frequency
channel. The algorithm is designed with emphasis on reliability
in the sense that erroneous depth detections are never output.
Whenever the quality of a detection is questionable the
algorithm outputs a depth of 0.00 to indicate that no reliable
detection was obtained. The ES60 algorithm is designed to
handle a number of difficult situations. The algorithm maintains
bottom lock for a discontinuous jump in bottom depth. It avoids
false bottom detections on a dense school of fish. The algorithm
chooses the upper boundary of the first layer when the bottom
consists of layers.
6
857-160970 / Rev.H
System description
The bottom detection algorithm locks to the first good bottom
return. The depth at point A rather than the depth along the
transducer axis will be output for a sloped bottom. The detected
depth value is always smaller than the depth along the
transducer axis implying that a safety margin is automatically
included.
857-160970 / Rev.H
7
Simrad ES60
Split-beam operation
The ES60 uses the split-beam technique for assessment of the
size distribution of individual fish. A split-beam transducer is
electrically divided into four quadrants. All four quadrants are
excited in parallel during transmission. However, the received
signal from each quadrant is separately amplified in a
four-channel matched receiver allowing the direction of arrival
of an echo to be determined.
Figure 3 Split-beam principles
An acoustic wave front propagating towards the transducer
arrives at the four quadrants at different times causing the phase
angle of the electrical output signal from the quadrants to differ.
The fore-and-aft angle is determined from the electrical phase
difference between the fore and the aft transducer halves, and
the athwartships angle is determined from the starboard and port
signals.
Fish A is positioned along the transducer axis where the
transducer has its maximum sensitivity, while Fish B is
positioned towards the edge of the beam where the sensitivity is
lower. Evidently, the echo signal from Fish A will be stronger
than the signal from Fish B even though they are of the same
size and at the same depth. Hence, determining fish size from
8
857-160970 / Rev.H
System description
the received echo strength alone will not be too successful. A
split-beam echo sounder measures the position of the fish within
the beam. The sounder corrects for the difference in transducer
sensitivity and computes the true size of the fish.
The split-beam measurement technique only works for echoes
originating from one single fish since the electrical phase will be
random if echoes from multiple individuals at different positions
in the beam are received simultaneously.
Consequently, measurement of fish size inside a school of fish
tends to be unreliable.
857-160970 / Rev.H
9
Simrad ES60
Observation range
Absorption increases dramatically with frequency in salt water.
For maximum observation range you should select a low
operating frequency, a large transducer and the maximum
transmit power.
10
Figure 4 Observation range
Maximum detection depth
Transducer Frequency,
kHz
12--161216.40193200085010000
ES 18188.21382200011007000
27--26278.18387300011004400
38/200D384.0976610005002100
38--9384.0976615008002600
38--7384.0976620009502800
50/200D502.05149310005001500
50--7502.05149320007001900
ES70--11702.0515268004501100
Pulse
duration,
ms
Band
width,
Hz
Transmit
power,
W
Range
fish,
m
857-160970 / Rev.H
Range
bottom,
m
System description
TransducerRange
120--251201.0230261000390800
ES120--71201.0230261000440850
50/200D2001.0330881000280550
ES200--72001.0330881000270550
Frequency,
kHz
Pulse
duration,
ms
Band
width,
Hz
Transmit
power,
W
Range
fish,
m
bottom,
m
Typical observation ranges are shown in the figure. Using the
Simrad 27-26/21 transducer (27 kHz, 10x13 degrees, 3000 W)
you can observe a 60 centimeter cod down to 800 meters, and
bottom detection works down to 3800 meters. However, with
the Simrad 200-7F transducer (200 kHz, 7x7 degrees, 1000 W)
you can only observe that same cod down to 260 meters, and
bottom detection becomes unreliable below 500 meters.
These range calculations assume a normal sea water salinity
(3.5%) and temperature (+10 degC), an average bottom (surface
backscattering strength = -20 dB) and a noise level typical for a
moving vessel.
857-160970 / Rev.H
11
Simrad ES60
DISPLAY VIEWS
Introduction
This chapter provides a brief overview of the information
displayed by the ES60, and how it is organised.
Related topics
→Display layout and main view, page 13
→Moving boundary lines, page 14
→Direct access to dialog boxes, page 15
→Menu bar, page 16
→Header view, page 17
→Echo frames, page 18
→Status bar, page 21
→History and printer views, page 22
12
857-160970 / Rev.H
Display organisation
Main view
The ES60 display is organised as follows (from top):
• Menu bar
• For each transceiver channel:
- Two echo frames
• Status bar
A single channel display is shown below as an example.
Display views
AB
C
DEF
857-160970 / Rev.H
(CD10202)
(A) Main menu(B) Header view
(C) Echogram and range view(D) Scope view
(E) Single echo view(F) Status bar
13
Simrad ES60
Menu
The Menu bar contains the echo sounder’s main menu. A
single click on one of the menu names will provide a new
drop-down menu where additional choices can be made.
Header
For each channel, the Header view contains the current
operational mode and frequency, the current depth, and the
colour scale.
Echo frames
The Echo frame takes up the largest part of the echo sounder
window. Each Echo frame contains (from left) a Single Echo
view, an Echogram and Range view and a Scope view.
The Echo frame view is are also described in more detail in the
Getting started chapter.
Status bar
The Status bar presents the current event and line numbers,
current time, and other information provided by the echo
sounder.
Moving the boundary lines
You can modify the vertical size of the echograms by moving
the horizontal boundary line between the two echograms.
To do this:
1Position the cursor at the boundary line.
2Press the left mouse button.
3Drag the cursor up or down vertically while keeping the
left mouse button pressed.
4Release the left mouse button.
Using the same operation, you can modify other boundary lines
on the display;
• The horizontal line between the upper Echo frame and the
Header view
14
• The vertical line between the Echogram and Range view
and the Scope view
• the vertical line between the Echogram and Range view and
the Single Echo view.
857-160970 / Rev.H
Display views
Direct access to dialogue boxes
Several dialogue boxes are directly accessed from the various
views on the display.
Position the cursor, and right-click on the...
• Mode and frequency information in the Header view to
open the Transceiver Settings dialogue box.
• Depth value in the Header view to open the Bottom
Detector dialogue box.
• Colour scale in the Header view to open the Colour Scale
dialogue box.
• Range fieldintheEchogram and Range view to open one
of the Range dialogue boxes, depending of the current
echogram type.
• Echogram field in the Echogram and Range view to open
the Echogram dialogue box.
• Single Echo view to open the Echo Trace dialogue box.
Related topics
→Menu bar, page 16
→Header view, page 17
→Echo frames, page 18
→Status bar, page 21
→Getting started; Operation, page 30
→Bottom Detector, page 78
→Colour Scale, page 81
→Echogram, page 85
→Bottom Range, page 80
→Surface Range, page 115
→Transceiver settings, page 119
→Echo Trace, page 84
857-160970 / Rev.H
15
Simrad ES60
Menu bar
The ES60 Menu bar contains the Main menu.
AB
(CD10204)
(A) Main menu
(B) Menu bar
The main menu has the following options:
• File
• View
• Options
• Install
• Step!
• Help
To operate, click on the menu name and observe the drop-down
menu. Select a new item on the drop-down menu by clicking on
the command. Commands shown with light grey colour are
unavailable in the present configuration or operational mode.
The menus are all explained in the Reference Guide.
Related topics
→Main menu, page 58
→Reference guide, page 57
16
857-160970 / Rev.H
Header view
Display views
The ES60 Header view is shown directly above the two Echo
frames. The top Header view is thus located just below theMenu bar. The Header view contains the following
information.
AB
(A) Transceiver settings: Current mode and frequency
(B) Bottom detection: Current depth
(C) Colour Scale
The Header view is a part of the channel. If more than one
channel is displayed, the Header view is duplicated as well.
The Header view provides direct access to the following
dialogue boxes:
• Right-click in the Transceiver settings field (on the Mode
and frequency information) to open the TransceiverSettings dialogue box.
• Right-click in the Bottom detection field (on the Depth
value) to open the Bottom Detector dialogue box.
• Right-click on the Colour scale to open the
dialogue box.
Colour Scale
C
(CD10205)
857-160970 / Rev.H
Related topics
→Transceiver Settings, page 119
→Bottom Detector, page 78
→Colour Scale, page 81
17
Simrad ES60
Echo frames
Overview
The ES60 Echo frames are the main information bearer on the
echo sounder display. The Echo frames are usually presented in
pairs with two echo frames for each channel.
The Echo frame contains the following views:
(A) Single echo view
(B) Echogram and Range view
(C) Scope view
Note that the Single Echo view is only available in split-beam
versions of the echo sounder.
AB
Single Echo
The Single Echo view contains information on detection of
single echoes. Two plots are visible in this view:
• The top plot shows a histogram of the fish size distribution
for the single echoes detected in the echogram.
C
(CD10206)
18
• The bottom plot shows the position within the beam of the
detected single echoes for the current ping (largest circles)
and the three previous ping (smaller circles).
• The upper right corner of the view shows the Biomass value
calculated from the total biomass of fish, plancton etc from
the current echogram.
Note that the colours used to display this information are
determined from the settings in the Colour Scale.
857-160970 / Rev.H
Display views
If you place the cursor in the coordinate system, a small yellow
label will appear to give you a detailed readout of the target
strength in dB at the cursor’s position. This target strength
indicates the fish length (in cm or inches) or fish weight (in kg).
Related topics
→Getting started, page 31.
→Colour Scale, page 81.
Echogram and Range
The Echogram and Range view consists of an Echogram field
to the left and a Range field to the right. These are separated by
the vertical range axis. The Echogram field contains
information about the acoustical values, while the Range field is
used for specifying the range used in the Echogram field. The
settings in the Colour Scale is used to present the information.
In the echogram field, the presentation can be of different views.
This can be selected in echogram dialogue bok as 1x, 3x, 5x, or
all. Fore examle: If a 20 tranducer system; all selected, 20
echogram in the echogram filed.
When you place the cursor in the Echogram field, you can use
the mouse wheel to modify the gain setting, and hence the
display colour sensitivity. Each click of the wheel corresponds
to a 1 dB change. The same gain setting is available from the
Colour Scale dialogue box.
Whenever the cursor is located within the Echogram field, a
small yellow label is visible. The label provides the following
information:
• Left: Depth at the cursor position
• Middle: Diameter coverage from the transducer beam
• Right: Current gain setting
To change the range, you can also use the mouse wheel. Place
the cursor inside the Range fieldtodothis:
• In a surface related echogram you will modify the range,
while for a bottom related echogram, you will change the
start range.
• If you press the left mouse button while you use the mouse
wheel, the surface echogram will change its start value, while
the bottom related echogram will change its range.
857-160970 / Rev.H
Related topics
→Getting started, page 32
→Colour Scale, page 81
19
Simrad ES60
Scope
The Scope view is the rightmost view and shows a oscilloscope
view of the last ping corresponding to the settings in the
Echogram view.
This view draws a range of horizontal symmetrical colour lines.
The distance from the vertical centre axis and the line colour
reflects the received echo amplitude. A black horizontal line
across the view indicates the current bottom view.
Channel:
Test presentation for passive or test mode
Passive:
Background Noise: yyy.y dBW
Receiver Amplitude: xxx.x dBW
Alongship angle: z.zz deg
Athwarthship Angle: z.zz deg
The background noise shown is the median of 20 equidistance
power samples in the total range of the current ping. The
receiver and the two angles (alongship and athwarthship) are
sampled at 100 m depth. During replay, you may find that this
depth setting is not availbale because the depth is less than 100
m. The receiver amplitude is then set to a minimum (235 dBW),
and the angles are set to zero.
20
857-160970 / Rev.H
Status bar
Display views
The ES60 Status bar is located at the bottom of the display. It
contains the following information:
Note that the water temperature read-out will only be available
if a sensor is connected to the echo sounder. Also, navigational
information requires that the applicable position information is
connected to the echo sounder.
(CD10208)
AB
(A) Information applicable f or the current operation
(B) Event number
(C) Printer logo (when printer is active)
(D) Current temperature
(E) Storage line number
(F) Navigational information (latitude and longitude)
(G) Time
Related topics
→Status bar, page 66
C
D
E
F
G
857-160970 / Rev.H
21
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