Kongsberg EA640, Руководство по установке

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413764/B
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Acoustic noise
Topics
Contributing factors, page 25
Self noise, page 27
Ambient noise, page 29
Electrical self noise, page 29
Some means to reduce acoustic noise, page 30
Contributing factors
Several factors are contributing to the performance of the hydroacoustic equipment
used on board a vessel.
Factors contributing to the performance of the hydroacoustic equipment used on board a
vessel are:
• 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 the user to make the right filter 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.
Signal-to-noise ratio (often abbreviated SNR or S/N) is a measure used in
science and engineering that compares the level of a desired signal to the level of
background noise. It is defined as the ratio of signal power to the noise power, often
expressed in decibels. A ratio higher than 1:1 (greater than 0 dB) indicates more
signal than noise. While SNR is commonly quoted for electrical signals, it can
be applied to any form of signal [...].
http://en.wikipedia.org/wiki/Signal_to_noise_ratio (September 2013)
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
Preparations