Echo sounding is a type of sonar used to determine the depth of water by sending a sound pulse into the water. The time interval between the emissions and pulse repayment is recorded, which is used to determine the water depth along with the speed of sound in the water at that time. This information is typically used for navigation purposes or for obtaining depth for graphics purposes. An echo can also refer to a hydroacoustic "echo sound" defined as the active voice in water (sonar) used to study fish. The hydroacoustic assessment traditionally uses cellular surveys from boats to evaluate fish biomass and spatial distribution. In contrast, location techniques still use stationary transducers to monitor passing fish.
The sound word is used for all types of depth measurements, including ones that do not use sound, and are unrelated to the sound in the sense of sound or tone. The echo sound is a method of depth measurement that is faster than the previous technique of lowering the line that sounds to the base.
Video Echo sounding
Technology
Distance is measured by multiplying half the time of the signal coming out of the pulse to its return with the speed of sound in the water, which is approximately 1.5 kilometers per second [TÃÆ' Â · 2ÃÆ'â € (4700 feet per second or 1.5 kil per second )] For proper echosounding applications, such as hydrographics, the speed of sound should also be measured normally by deploying the sound probe speed into the water. Effective echo sound is a special purpose sonar app that is used to find the bottom. Since the traditional pre-SI water unit of depth is the depa, the instrument used to determine the water depth is sometimes called the fathometer . The first practical fathometer was invented by Herbert Grove Dorsey and patented in 1928.
Most ocean depths mapped using average or standard sound speeds. Where greater accuracy is required on average and even seasonal standards can be applied to the marine areas. For high accuracy depths, usually limited to special purpose or scientific surveys, sensors can be derived to measure temperature, pressure, and salinity. These factors are used to calculate the actual sound velocity in the local water column. This latter technique is regularly used by the US Coastal Survey Office for a US coastal waters navigation survey. See NOAA Field Procedure Manual, website of the Coast Survey Office (http://www.nauticalcharts.noaa.gov/hsd/fpm/fpm.htm).
Maps Echo sounding
General use
As well as assistance for navigation (most larger vessels will have at least a simple depth sounder), echo sounding is usually used for fishing. Variation of elevation often represents the places where fish gather. The fish school will also register. A fishfinder is an audible echo device used by recreational and commercial fishermen.
Hydrography
In areas where detailed bathymetry is required, an appropriate sound echo can be used for hydrographic work. There are many considerations when evaluating such a system, not limited to vertical accuracy, resolution, beamwidth acoustic emission/reception file and acoustic frequency transducers.
Most hydrographic echosounders are double frequencies, which means that low frequency pulses (usually around 24 kHz) can be transmitted at the same time as high frequency pulses (usually around 200 kHz). Since the two frequencies are different, the two return signals are usually not interfering with each other. There are many advantages of dual frequency echosounding, including the ability to identify vegetation layers or soft sludge over layers of rock.
Most hydrographic operations use a 200 kHz transducer, which is suitable for work on land up to a depth of 100 meters. Deeper water requires a lower frequency transducer because the lower frequency acoustic signal is less susceptible to damping in the water column. Frequencies commonly used for deep water sounds are 33 kHz and 24 kHz.
The beamwidth of the transducer is also a consideration for the hydrographer, since to get the best resolution of the data collected, narrow beamwidth is preferred. This is especially important when heard in deep water, because traces generated from acoustic pulses can be very large after reaching the distant sea floor.
In addition to a single echo sounder, there is a sound echo that is able to receive a lot of "ping" back. This system is described further in a section called echosounder multibeam.
Sound echoes are used in laboratory applications to monitor sediment transport, exploring and erosion processes in scale models (hydraulic models, flumes etc.). It can also be used to create 3D contour plots.
Standard for echo hydrographic sound
The accuracy and accuracy required of echo hydrographic sounds is determined by the requirements of the International Hydrographic Organization (IHO) for surveys to be performed under IHO standards. These values ​​are listed in the publication IHO S44.
To meet this standard, surveyors should consider not only the vertical and horizontal accuracy of sound and echo transducers, but the overall survey system. A motion sensor can be used, especially the heave component (in single beam echosounding) to reduce the sound for the movement of the ship experienced on the surface of the water. After all the uncertainties of each sensor are established, the hydrographer will create a budget uncertainty to determine whether the survey system meets the requirements set by IHO.
Different hydrographic organizations will have a set of field and manual procedures to guide their surveyors to meet the required standards. Two examples are the US Army Corps of Engineers publication EM110-2-1003, and NOAA 'Field Procedures Manual'.
History
German inventor Alexander Behm granted German patent No. 282009 for the invention of audible echoes (a tool for measuring the depth of the sea and distance and the title of a ship or obstacle by reflecting sound waves) on July 22, 1913.
One of the first commercial echo sound units is the Fnessenden Fathometer, which uses Fessenden oscillators to produce sound waves. It was first installed by Submarine Signal Company in 1924 at M & amp; M liner S.S. Berkshire.
References
External links
Media related to Echo is heard on Wikimedia Commons
- "How Depth Say The Depth of Water Under The Ship" Monthly Popular Mechanics , July 1930 - draws the detail of the initial depth finder using an echo
- ELAC (1982) Introduction to Echosounding . Honeywell-ELAC-Nautik GmbH, Kiel, 88 pp, (pdf 27.5 MB)
Also see
- Alexander Behm - inventor
- acoustic oceanography
- AUV
- fishery acoustics
- Fessenden oscillator
- Hydroacoustics
- Sonar
- Listen to the line
- Sound
- underwater acoustics
- Hydrographic Survey
Source of the article : Wikipedia
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