Fishing Gear Noise; Electrical Noise; Some Means To Reduce Acoustic Noise - Simrad EK80 Installation Manual

Preparations
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Precipitation noise
In some areas, where many vessels are operating together the engine and propeller noise
from other vessels might be disturbing.
Interference from hydroacoustic instruments located in other vessels may also be a limiting
factor.
The sea noise is as can be expected dependent on the weather conditions. In bad weather
the sea noise can be quite high.

Fishing gear noise

Whenever your fishing gear is in use, it will create noise.
A bottom trawl, for instance, is a considerable noise maker.
Still, this noise will seldom be a limiting factor for hull mounted sonars or echo sounders.
However, for operation of a catch monitoring system or a trawl sonar, with the transducer(s)
placed on the trawl, the gear noise is one of the main contributors to the noise level.

Electrical noise

Electrical or electronic noise is picked up or generated in any other part of the equipment
than the transducer.
Hum picked up by the transducer cables or picked up from the voltage supply is usually the
most common source of electrical noise.
At higher frequencies – where rather wide bandwidths are necessary – the noise from
components, transistors or other analogue electronic may be a limiting factor.

Some means to reduce acoustic noise

Careful planning of the EK80 installation may reduce the acoustic noise.
Unfortunately, it is impossible to simply provide a number of specific procedures to reduce
the noise.
An important factor is the physical location of the transducer. This depends on the vessel's
design and construction, how the hull is shaped, and how the water runs along the hull.
Other factors deal with other equipment mounted on board, and this will also be vessel
dependant.
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