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Depth sounding, often simply called sounding, is measuring the depth of a body of water. Data taken from soundings are used in bathymetry to make maps of the floor of a body of water, such as the seabed topography .
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 ...
Early depth sounding was achieved using lead line sounding (or sounding line), where a lead weight attached to a length of rope marked with depth values.As this method was mechanical in nature, the only correction that was applied to the sounding was the reduction of the sounding for tidal height.
Bathymetric charts showcase depth using a series of lines and points at equal intervals, called depth contours or isobaths (a type of contour line). A closed shape with increasingly smaller shapes inside of it can indicate an ocean trench or a seamount, or underwater mountain, depending on whether the depths increase or decrease going inward.
Echo sounding is a process used to determine the depth of water beneath ships and boats. A type of active sonar, echo sounding is the transmission of an acoustic pulse directly downwards to the seabed, measuring the time between transmission and echo return, after having hit the bottom and bouncing back to its ship of origin.
Echo sounding is effectively a special purpose application of sonar used to locate the bottom. Since a traditional pre- SI unit of water depth was the fathom , an instrument used for determining water depth is sometimes called a fathometer .
The first instrument used for deep-sea investigation was the sounding weight, used by British explorer Sir James Clark Ross. [4] With this instrument, he reached a depth of 3,700 m (12,139 ft) in 1840. [5] The Challenger expedition used similar instruments called Baillie sounding machines to extract samples from the sea bed. [citation needed]
A multibeam echosounder is a device typically used by hydrographic surveyors to determine the depth of water and the nature of the seabed. Most modern systems work by transmitting a broad acoustic fan shaped pulse from a specially designed transducer across the full swathe acrosstrack with a narrow alongtrack then forming multiple receive beams (beamforming) that are much narrower in the ...