Installation manual

Simrad SH80
The echoes from the bottom will vary with how uneven the
bottom is, what kind of bottom you have under your vessel,
(rock, mud, sand etc.) as well as your current tilt setting. The
echo from the sea surface will vary with the current sea state and
your current tilt setting.
The illustration demonstrates how the bottom and the sea surface
return echoes back to your sonar transducer. In situation (A) you
will see several weak echoes from the waves and from the rock on
the bottom, you will still be able to identify the school of fish. In
situation (B) you will be able to identify the upper school of fish,
but the lower school will be hidden in the shadow of the rock.
Be aware of that other vessels close to you will also generate
reverberation due to the water disturbance caused by the wake,
the propellers and the cooling water spill.
Blocking
The movement of your vessel through the water will often
— especially in higher sea states — cause air bubbles to be
generated, and these bubbles will move along the hull. This is
called blocking. In order to prevent this noise from disturbing
your sonar operations, it is important to lower the sonar
transducer as far down below the hull as possible.
Check the noise yourself!
If you are bothered with acoustic or electric noise, you can easily
run a few simple tests to identify the cause of the problem.
Check the noise
1 Click the Setup tab to open the menu.
2 Click the
Test button to open the System test menu.
3 Click the
Test config button, and select Noise and VR in the
parameter dialogue.
4 Click the
Close button in the parameter dialogue to close it.
5 Click the
Horizontal tab to open the menu.
6 Observe the
Noise level button, and read the noise level.
The level your read in the button is the current noise in the
direction of the cursor. The noise is provided in dB, and the
number should be as negative as possible. For example, a reading
of –50 dB means that you have less noise than if you read –40 dB.
In order to reduce the noise, try to adjust the propeller pitch and
the number of revolutions.
Check electrical noise
1 Switch off all electric equipment that can cause electrical
noise.
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