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Echosounder
Echo sounding or depth sounding is the use of sonar for ranging, normally to determine the depth of water (bathymetry). 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 between sonar and target. This information is then typically used for navigation purposes or in order to obtain depths for charting purposes. Echo sounding can also be used for ranging to other targets, such as fish schools. Hydroacoustic assessments have traditionally employed mobile surveys from boats to evaluate fish biomass and spatial distributions. Conversely, fixed-location techniques use stationary transducers to monitor passing fish. The word '' sounding'' is used for all types of depth measurements, including those that don't use sound, and is unrelated in origin to the word ''sound'' in the sense of noise or ton ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multibeam Echosounder
A multibeam echosounder (MBES) is a type of sonar that is used to map the seabed. It emits acoustic waves in a fan shape beneath its transceiver. The time it takes for the sound waves to reflect off the seabed and return to the receiver is used to calculate the water depth. Unlike other sonars and echo sounders, MBES uses beamforming to extract directional information from the returning soundwaves, producing a swath of depth soundings from a single ping. History and progression Multibeam sonar sounding systems, also known as ''swathe'' (British English) or ''swath'' (American English), originated for military applications. The Sonar Array Sounding System (SASS) was developed in the early 1960s by the US Navy, in conjunction with General Instrument to map large swaths of the ocean floor to assist the underwater navigation of its submarine force. SASS was tested aboard the USS ''Compass Island'' (AG-153). The final array system, composed of sixty-one one degree beams with a swa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sonar
Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigation, navigate, measure distances (ranging), communicate with or detect objects on or under the surface of the water, such as other vessels. "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. Acoustic location in air was used before the introduction of radar. Sonar may also be used for robot navigation, and SODAR (an upward-looking in-air sonar) is used for atmospheric investigations. The term ''sonar'' is also used for the equipment used to generate and receive the sound. The acoustic frequencies used in sonar systems vary from very low (infrasonic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bathymetry
Bathymetry (; ) is the study of underwater depth of ocean floors (''seabed topography''), lake floors, or river floors. In other words, bathymetry is the underwater equivalent to hypsometry or topography. The first recorded evidence of water depth measurements are from Ancient Egypt over 3000 years ago. Bathymetric (or hydrographic) charts are typically produced to support safety of surface or sub-surface navigation, and usually show seafloor relief or terrain as contour lines (called depth contours or isobaths) and selected depths ('' soundings''), and typically also provide surface navigational information. Bathymetric maps (a more general term where navigational safety is not a concern) may also use a Digital Terrain Model and artificial illumination techniques to illustrate the depths being portrayed. The global bathymetry is sometimes combined with topography data to yield a global relief model. Paleobathymetry is the study of past underwater depths. Seabed topography ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Echo Sounding USN
In audio signal processing and acoustics, an echo is a reflection (physics), reflection of sound that arrives at the listener with a delay after the direct sound. The delay is directly proportional to the distance of the reflecting surface from the source and the listener. Typical examples are the echo produced by the bottom of a well, by a building, or by the walls of an enclosed room and an empty room. A true echo is a single reflection of the sound source. The word ''echo'' derives from the Greek language, Greek ἠχώ (''ēchō''), itself from ἦχος (''ēchos''), "sound". Echo (mythology), Echo in the Greek folk story is a mountain nymph whose ability to speak was cursed, leaving her able only to repeat the last words spoken to her. Some animals use echo for location sensing and navigation, such as cetaceans (dolphins and whales) and bats in a process known as Animal echolocation, echolocation. Echoes are also the basis of Sonar technology. Acoustic phenomenon Acoustic w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fathom
A fathom is a unit of length in the imperial and the U.S. customary systems equal to , used especially for measuring the depth of water. The fathom is neither an International Standard (SI) unit, nor an internationally-accepted non-SI unit. Historically, however, it is the most frequently employed maritime measure of depth in the English-speaking world. There are two yards (6 feet) in an imperial fathom. Originally the span of a man's outstretched arms, the size of a fathom has varied slightly depending on whether it was defined as a thousandth of an (Admiralty) nautical mile or as a multiple of the imperial yard. Formerly, the term was used for any of several units of length varying around . Name The name (pronounced ) derives from the Old English word ''fæðm'', cognate to the Danish (via the Vikings) word "favn" meaning embracing arms or a pair of outstretched arms. Cognate maybe also via the Old High German word "fadum" of the same meaning.''Oxford English Dictionary' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Hydrographic Organization
The International Hydrographic Organization (IHO) is an intergovernmental organisation representing hydrography. , the IHO comprised 98 Member States. A principal aim of the IHO is to ensure that the world's seas, oceans and navigable waters are properly surveyed and charted. It does this through the setting of international standards, the co-ordination of the endeavours of the world's national hydrographic offices, and through its capacity building program. The IHO enjoys observer status at the United Nations, where it is the recognised competent authority on hydrographic surveying and nautical charting. When referring to hydrography and nautical charting in Conventions and similar Instruments, it is the IHO standards and specifications that are normally used. History The IHO was established in 1921 as the International Hydrographic Bureau (IHB). The present name was adopted in 1970, as part of a new international Convention on the IHO adopted by the then member nations. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sensor Resolution
A sensor is a device that produces an output signal for the purpose of sensing a physical phenomenon. In the broadest definition, a sensor is a device, module, machine, or subsystem that detects events or changes in its environment and sends the information to other electronics, frequently a computer processor. Sensors are always used with other electronics. Sensors are used in everyday objects such as touch-sensitive elevator buttons (tactile sensor) and lamps which dim or brighten by touching the base, and in innumerable applications of which most people are never aware. With advances in micromachinery and easy-to-use microcontroller platforms, the uses of sensors have expanded beyond the traditional fields of temperature, pressure and flow measurement, for example into MARG sensors. Analog sensors such as potentiometers and force-sensing resistors are still widely used. Their applications include manufacturing and machinery, airplanes and aerospace, cars, medicine, robot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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