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Underwater acoustics (also known as hydroacoustics) is the study of the propagation of sound in water and the interaction of the mechanical waves that constitute sound with the water, its contents and its boundaries. The water may be in the ocean, a lake, a river or a tank. Typical frequencies associated with underwater acoustics are between 10 ...
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 ...
SOFAR channel. Underwater sound speed as a function of depth. Data derived from readings taken north of Hawaii in the Pacific Ocean and sourced from the World Ocean Atlas, 2005 edition. Note the SOFAR channel axis at ca. 750 m depth, where sound speed is shown at its lowest. The SOFAR channel (short for sound fixing and ranging channel), or ...
Fessenden oscillator. A Fessenden oscillator is an electro-acoustic transducer invented by Reginald Fessenden, with development starting in 1912 at the Submarine Signal Company of Boston. [1] It was the first successful acoustical echo ranging device. Similar in operating principle to a dynamic voice coil loudspeaker, it was an early kind of ...
Bistatic sonar. Bistatic sonar is a sonar configuration in which transmitter and receiver are separated by a distance large enough to be comparable to the distance to the target. Most sonar systems are monostatic, in that the transmitter and receiver are located in the same place. A configuration with multiple receivers is called multistatic.
Sonar signal processing. Sonar systems are generally used underwater for range finding and detection. Active sonar emits an acoustic signal, or pulse of sound, into the water. The sound bounces off the target object and returns an echo to the sonar transducer. Unlike active sonar, passive sonar does not emit its own signal, which is an ...
In oceanography, a sofar bomb (Sound Fixing And Ranging bomb), occasionally referred to as a sofar disc, [1] is a long-range position-fixing system that uses impulsive sounds in the deep sound channel (SOFAR channel) of the ocean to enable pinpointing of the location of ships or crashed planes. The deep sound channel is ideal for the device, as ...
RAFOS floats[1] are submersible devices used to map ocean currents well below the surface. They drift with these deep currents and listen for acoustic "pongs" emitted at designated times from multiple moored sound sources. By analyzing the time required for each pong to reach a float, researchers can pinpoint its position by trilateration.