Fishing Gear Noise; Electrical Self Noise; Some Means To Reduce Acoustic Noise - Simrad ES80 Reference Manual

Concept descriptions
Related topics
Acoustic noise, page 462
BITE: Noise page, page 409

Fishing gear noise

Whenever your fishing gear is in use, it will create noise.
A bottom trawl, for instance, is a considerable source of acoustic noise. Still, this
noise from the fishing gear 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 placed on the trawl, the gear noise is one of the main contributors
to the noise level.
Related topics
Acoustic noise, page 462
BITE: Noise page, page 409

Electrical self noise

Electrical or electronic self 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 power supply is usually
the most common source of electrical self noise. At higher frequencies – where rather
wide bandwidths are necessary – the noise from components, transistors or other
analogue electronic may be a limiting factor.
Related topics
Acoustic noise, page 462
BITE: Noise page, page 409

Some means to reduce acoustic noise

Several factors are contributing to the performance of the hydroacoustic equipment used
on board a vessel. Careful planning of the ES80 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 transducers. 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. At moderate ship speeds the machinery noise is usually dominant. At
medium speeds the flow noise increases more rapidly and takes over, while at higher
speed the propeller noise will be the main contributor.
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