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Simrad ER60 Operator manual
38
b Select a range that will provide a noise recording with
at least two or three colours on the echogram.
7
On the Output menu, select File to open the File Output
dialogue. Set the following parameters:
a Same range as in the echogram
b 0 Mb maximum file size
8
Start the echo sounder.
Test loop: Increasing speed
Start the test loop with vessel speed 0 knots.
1
Make a short echogram recording, find the background
noise in the Numerical view, and note down the value.
2
Increase the vessel speed with 1 or 2 knots, and wait until
the speed is stable.
3
Repeat the loop until the vessel has reached maximum
speed.
Decreasing speed
Start with maximum vessel speed.
1
Start echogram recording.
2
Disengage the propeller as quickly as possible to allow the
vessel to slow down by itself.
3
Write down the time to tag each 1 or 2 knots speed
decrease.
4
Stop the echogram recording once the vessel has stopped.
If the noise decreases quickly towards the same level as at 0
knots when the propeller has been disengaged, this means that
the propeller mainly generates the noise. If the noise at
decreasing vessel speed is more or less equal to the noise level
at increasing speed, the noise is probable flow-noise. Usually
the noise is a combination of both.
Evaluation
If the noise is substantial and mainly caused by the propeller, the
procedure should be repeated with different combinations of
pitch and propeller speed if possible, to determine the most
favourable settings.
The echogram recording will give you immediate information
regarding the maximum possible detection range for the chosen
settings. The light grey colour on the echogram relates the depth
where the noise will mask the useful echo from biomass.
850-164692 / Rev.B
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