Kongsberg Simrad SN90 Reference Manual page 639

transmitting and receiving systems are key factors during our product development,
while our end user documentation aims to help you 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 [...].
Wikipedia, Copied 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 is necessary to keep the noise level as low as possible in order to obtain high echo
interpretation.
The noise that contributes to the signal to noise ratio may be divided into the following
types of noise:
• Self noise
• Ambient noise
• Electrical noise
• Reverberation
• Underwater noise
• Fishing gear noise
(This is a generic illustration. Any similarities with specific products are accidental.)
The transducer can pick up noise from:
A
• Biological disturbances
• Interference
• Cavitation
• Propeller noise
381294/E
Concept descriptions
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