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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''. Bistatic vs monostatic Propagation (transmission) loss This is a loss in sound level which happens while the sound pulse travels from projector to target and from target to receiver. There are 3 different mechanisms causing transmission Loss: spherical (or cylindrical in shallow water) spreading, absorbing and scattering by ocean media inhomogeneities. Transmission loss (TL) is proportional to range, (the farther the sound travels the more the loss), and to sound frequency. In monostatic sonar the sound first travels from projector to target, then the same way back from target to receiver, so two-way loss is just 2TL, where TL is one-way loss. In bist ... [...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] |
Underwater Acoustics
Underwater acoustics 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 Hz and 1 MHz. The propagation of sound in the ocean at frequencies lower than 10 Hz is usually not possible without penetrating deep into the seabed, whereas frequencies above 1 MHz are rarely used because they are absorbed very quickly. Underwater acoustics is sometimes known as hydroacoustics. The field of underwater acoustics is closely related to a number of other fields of acoustic study, including sonar, transduction, signal processing, acoustical oceanography, bioacoustics, and physical acoustics. History Underwater sound has probably been used by marine animals for millions of years. The science of underwater acoustics began in 1490, when Leonardo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Target Scattering Pattern
Target may refer to: Physical items * Shooting target, used in marksmanship training and various shooting sports ** Bullseye (target), the goal one for which one aims in many of these sports ** Aiming point, in field artillery, fixed at a specific target * Color chart (or reference card), the reference target used in digital imaging for accurate color reproduction Places * Target, Allier, France * Target Lake, a lake in Minnesota Terms * Target market, marketing strategy ** Target audience, intended audience or readership of a publication, advertisement, or type of message * In mathematics, the target of a function is also called the codomain * Target (cricket), the total number of runs a team needs to win People * Target (rapper), stage name of Croatian hip-hop artist Nenad Šimun * DJ Target, stage name of English grime DJ Darren Joseph, member of Roll Deep * Gui-Jean-Baptiste Target (1733–1807), French lawyer Art and media * The Target, a comic book charact ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bistatic Angle
Bistatic radar is a radar system comprising a transmitter and receiver that are separated by a distance comparable to the expected target distance. Conversely, a conventional radar in which the transmitter and receiver are co-located is called a monostatic radar. A system containing multiple spatially diverse monostatic or bistatic radar components with a shared area of coverage is called ''multistatic radar''. Many long-range air-to-air and surface-to-air missile systems use semi-active radar homing, which is a form of bistatic radar. Types Pseudo-monostatic radars Some radar systems may have separate transmit and receive antennas, but if the angle subtended between transmitter, target and receiver (the bistatic angle) is close to zero, then they would still be regarded as monostatic or pseudo-monostatic. For example, some very long range HF radar systems may have a transmitter and receiver which are separated by a few tens of kilometres for electrical isolation, but a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Babinet's Principle
In physics, Babinet's principle states that the diffraction pattern from an opaque body is identical to that from a hole of the same size and shape except for the overall forward beam intensity. It was formulated in the 1800s by French physicist Jacques Babinet. A quantum version of Babinet's principle has been derived in the context of quantum networks. State transfer in highly connected networks and a quantum Babinet principle, D. I. Tsomokos, M. B. Plenio, I. de Vega, and S. F. Huelga, Phys. Rev. A 78, 062310 (2008) Explanation Assume ''B'' is the original diffracting body, and ''B is its complement, i.e., a body that is transparent. The sum of the radiation patterns caused by ''B'' and ''B must be the same as the radiation pattern of the unobstructed beam. In places where the undisturbed beam would not have reached, this means that the radiation patterns caused by ''B'' and ''B must be opposite in phase, but equal in amplitude. Diffraction patterns from apertures or bodies o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Long Range Surveillance
Long-range surveillance (LRS) teams (pronounced "lurse") were elite, specially-trained surveillance units of the United States Army employed for clandestine operation by Military Intelligence for gathering direct human intelligence information deep within enemy territory. Classic LRS employment is to infiltrate deep into enemy territory, construct hide and surveillance sites, and provide continuous surveillance/special reconnaissance of an intelligence target of key interest. LRS teams allow 24-hour surveillance and analysis coverage unlike unmanned aerial vehicles (UAVs), manned aircraft, and most satellites. Assuming there is no mission compromise, these teams typically remain in position for up to 6 days, as determined by the availability of food and water. As a result of an evaluation conducted using computer-modelling the U.S. Army's senior leadership made the decision to deactivate all active-duty and National Guard LRS units. By the end of January 2017 the three active-duty ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Single Projector With Many Receivers
Single may refer to: Arts, entertainment, and media * Single (music), a song release Songs * "Single" (Natasha Bedingfield song), 2004 * "Single" (New Kids on the Block and Ne-Yo song), 2008 * "Single" (William Wei song), 2016 * "Single", by Meghan Trainor from the album '' Only 17'' Sports * Single (baseball), the most common type of base hit * Single (cricket), point in cricket * Single (football), Canadian football point * Single-speed bicycle Transportation * Single-cylinder engine, an internal combustion engine design with one cylinder, or a motorcycle using such engine * Single (locomotive), a steam locomotive with a single pair of driving wheels * As a verb: to convert a double-track railway to a single-track railway Other uses * Single (mathematics) (1-tuple), a list or sequence with only one element * Single person, a person who is not in a committed relationship * Single precision, a computer numbering format that occupies one storage location in computer memory at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Low Frequency Towed Sonar
Low or LOW or lows, may refer to: People * Low (surname), listing people surnamed Low Places * Low, Quebec, Canada * Low, Utah, United States * Lo Wu station (MTR code LOW), Hong Kong; a rail station * Salzburg Airport (ICAO airport code: LOWS), Austria Music * Low (band), an American indie rock group from Duluth, Minnesota Albums * ''Low'' (David Bowie album), 1977 * ''Low'' (Testament album), 1994 * ''Low'' (Low EP), 1994 Songs * "Low" (Cracker song), 1993 * "Low" (Flo Rida song), 2007 * "Low" (Foo Fighters song), 2002 * "Low" (Juicy J song), 2014 * "Low" (Kelly Clarkson song), 2003 * "Low" (Lenny Kravitz song), 2018 * "Low" (Sara Evans song), 2008 * "Low", by Camp Mulla * "Low", by Coldplay from '' X&Y'' * "Low", by Inna from the self-titled album * "Low", by Marianas Trench from ''Fix Me'' * "Low", by R.E.M. from '' Out of Time'' * "Low", by Silverchair from ''Young Modern'' * "Low", by Sleeping with Sirens from ''Feel'' * "Low", by Tech N9ne from '' K.O.D.'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
