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Besides mechanical produced vibrations, other sources are caused by the motion of the sea, slamming of the vessel on the waves and water depth to mention just a few. The main problem here is that they are less controllable. The engine-gearbox interaction is usually a source for noise and vibrations.
The main cause of sound attenuation in fresh water, and at high frequency in sea water (above 100 kHz) is viscosity. Important additional contributions at lower frequency in seawater are associated with the ionic relaxation of boric acid (up to c. 10 kHz) [ 7 ] and magnesium sulfate (c. 10 kHz-100 kHz).
In electronics, motorboating is a type of low frequency parasitic oscillation (unwanted cyclic variation of the output voltage) that sometimes occurs in audio and radio equipment and often manifests itself as a sound similar to an idling motorboat engine, a "put-put-put", in audio output from speakers or earphones.
Underwater acoustic communication is a technique of sending and receiving messages in water. [1] There are several ways of employing such communication but the most common is by using hydrophones . Underwater communication is difficult due to factors such as multi-path propagation , time variations of the channel, small available bandwidth and ...
Sonar (sound navigation and ranging or sonic navigation and ranging) [2] is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigate, measure distances , communicate with or detect objects on or under the surface of the water, such as other vessels.
The Train is the name given to a sound recorded on March 5, 1997, on the Equatorial Pacific Ocean autonomous hydrophone array. The sound rises to a quasi-steady frequency. According to the NOAA, the origin of the sound is most likely generated by a very large iceberg grounded in the Ross Sea, near Cape Adare. [10
In nautical terms, the word sound is used to describe the process of determining the depth of water in a tank or under a ship. Tanks are sounded to determine if they are full (for cargo tanks) or empty (to determine if a ship has been holed) and for other reasons.
When the fish enters the leading edge of the sonar beam, a display pixel is turned on. As the fish swims toward the centre of the beam, the distance to the fish decreases, turning on pixels at shallower depths. When the fish swims directly under the transducer, it is closer to the boat so the stronger signal shows a thicker line.