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Preparing the installation
Acoustic noise
As with any other hydroacoustic systems, the quality of the EM 2040 MKII echo data
and presentations are subject to unwanted acoustic noise. The echoes from any large and
small target must be detected inside the noise.
It is important that we keep the noise level as low as possible. This is necessary to obtain
long range and dependable interpretations of the echoes. Even with the advanced noise
filtering offered by the EM 2040 MKII system, we must address the noise challenge.
This is important during the planning and preparations for the installation of the EM
2040 MKII system.
Topics
Contributing factors, page 33
Self noise, page 34
Ambient noise, page 37
Electrical self noise, page 37
Some means to reduce acoustic noise, page 38
Contributing factors
Several factors are contributing to the performance of the hydroacoustic equipment
used on board a vessel.
Such factors include:
• The quality and properties of the transmitted signal
• The quality of the receiving system
• The operational settings made during operation
• The properties of the target(s)
• The signal-to-noise ratio
The majority of these factors can neither be controlled nor improved by means
of installation methods or transducer locations. The quality and properties of the
transmitting and receiving systems are key factors during our product development,
while our end user documentation aims to help you to make the right settings during
operation. As for the target properties, there is nothing any of us can do with those.
The signal-to-noise ratio, however, can be improved by making the correct choices
during installation.
The signal is the echo that we want to know something about, while the noise is any
unwanted signals or disturbances. The echo must be detected in the noise and therefore
it is necessary to keep the noise level as low as possible in order to obtain high echo
interpretation.
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