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USBL (ultra-short baseline, also known as SSBL for super short base line) is a method of underwater acoustic positioning. A USBL system consists of a transceiver, which is mounted on a pole under a ship, and a transponder or responder on the seafloor, on a towfish, or on an ROV. A computer, or "topside unit", is used to calculate a position ...
Also, the multiple sensors needed for the USBL transducer pole position and orientation compensation each introduce additional errors. Finally, the non-uniformity of the underwater acoustic environment cause signal refractions and reflections that have a greater impact on USBL positioning than is the case for the LBL geometry.
A modern fishfinder displays measurements of reflected sound on a graphical display, allowing an operator to interpret information to locate schools of fish, underwater debris and snags, and the bottom of a body of water. Fishfinder instruments are used both by recreational and commercial fishermen, as well as by marine biologists.
In 1981, acoustic positioning was proposed as part of the U.S. military's MX missile system. [10] A network of 150 covert transponder fields was envisioned. Submarines typically are guided by inertial navigation systems, but these dead reckoning systems develop position drift which must be corrected by occasional position fixes from a GNSS system.
It operates by using a transducer to emit a pulse through the water and listen for echos to return. Using that data, it's able to determine the distance from the strongest echo, which can be the seafloor, a concrete structure, or other larger obstacle. [7] A fishfinder is an echo sounding device used by both recreational and commercial fishers.
A transducer is a device that converts energy from one form to another. Usually a transducer converts a signal in one form of energy to a signal in another. [1] Transducers are often employed at the boundaries of automation, measurement, and control systems, where electrical signals are converted to and from other physical quantities (energy, force, torque, light, motion, position, etc.).
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 ...
A pole-zero plot shows the location in the complex plane of the poles and zeros of the transfer function of a dynamic system, such as a controller, compensator, sensor, equalizer, filter, or communications channel. By convention, the poles of the system are indicated in the plot by an X while the zeros are indicated by a circle or O.