Kongsberg Simrad ST90, Reference Manual

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https://en.wikipedia.org/wiki/Wave_interference — April 2016
Related topics
Improving the recognition of fish and schools using receiver filters, page 117
Concept descriptions, page 626
Acoustic noise, page 633
Ambient noise
Ambient noise is usually not a limiting factor to the performance of sonars and echo
sounders.
The ambient noise may be split up as follows:
•
Sea noise
: Air bubbles, seismic disturbances, waves, boundary turbulence, etc.
•
Biological noise
: Fish, mammals
•
Man made noise
: Other vessels, interference
•
Precipitation noise
: Heavy rain or hail
In some areas, where many vessels operate together, the engine and propeller noise from
other vessels may be disturbing. Interference from hydroacoustic instruments located in
other vessels may also be a limiting factor. The sea noise depends on the weather conditions.
In bad weather the sea noise can be quite high due to the waves.
Related topics
Improving the recognition of fish and schools using receiver filters, page 117
Concept descriptions, page 626
Acoustic noise, page 633
Electrical self noise
Electrical or electronic self noise is picked up or generated in any other part of the equipment
than the transducer.
The most common source of electrical self noise is hum. The hum is normally generated by
a low quality power supply. It is then picked up by the transducer cables and/or sensitive
electronic circuitry. At higher frequencies – where rather wide bandwidths are necessary –
the noise from components, transistors or other analogue electronic may be a limiting factor.
Simrad ST90 Reference Manual