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"Sonar" can refer to one of two types of technology: passive sonar means listening for the sound made by vessels; active sonar means emitting pulses of sounds and listening for echoes. Sonar may be used as a means of acoustic location and of measurement of the echo characteristics of "targets" in the water. [4]
The sonar modified for the test was an early version of SURTASS deployed in the MV Cory Chouest. [10] As a result of this test a "Committee on Low-Frequency Sound and Marine Mammals" was organized by the National Research Council. Their findings were published in 1994, in Low-Frequency Sound and Marine Mammals: Current Knowledge and Research ...
Echo sounding or depth sounding is the use of sonar for ranging, normally to determine the depth of water . It involves transmitting acoustic waves into water and recording the time interval between emission and return of a pulse; the resulting time of flight , along with knowledge of the speed of sound in water, allows determining the distance ...
A scientific echosounder is a device which uses sonar technology for the calibrated backscatter measurement of underwater physical and biological components—this device is also known as scientific sonar. Applications include bathymetry, substrate classification, studies of aquatic vegetation, fish, and plankton, and differentation of water ...
A Navy decision in 1949 led to studies by 1950 recommending the passive sonar potential of the SOFAR channel be exploited for the Navy's Anti-Submarine Warfare (ASW) effort. The recommendation included that $10 million a year be spent on research and development of the system.
During sonar tests on submarines, it is said that the areas surrounding the sonar transducers had less fouling than the rest of the hull [citation needed]. Antifouling (the removal of biofouling) has been attempted since ancient times, initially using wax, tar or asphalt.
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 advantage for military vessels.
Side-scan uses a sonar device that emits conical or fan-shaped pulses down toward the seafloor across a wide angle perpendicular to the path of the sensor through the water, which may be towed from a surface vessel or submarine (called a “towfish”), or mounted on the ship's hull.