Kongsberg Simrad MF90, Installation Manual

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476671/B
75
A
In this situation you will be able to identify the upper school of fish, but the lower
school will be hidden in the shadow of the seabed rock formation.
B
In this situation you will see several weak echoes from the waves and from the rock on
the bottom, but you will still be able to identify the school of fish.
The reverberation is caused by the transmission pulse itself. It can only be reduced by
shortening the pulse duration or using a smaller beamwidth.
Related topics
Preparations, page 42
Acoustic noise, page 68
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 installation may reduce the acoustic noise.
Unfortunately, it is impossible to simply provide a number of specific procedures to reduce
the noise.
The physical location of the installation trunk and the hull unit is important. 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.
Note
The information here must be considered as general advice. Each system installation must
be handled separately depending on the hull design and the other electrical and mechanical
systems installed on the vessel.
Preparations