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Underwater acoustic communication is a technique of sending and receiving messages in water. [1] There are several ways of employing such communication but the most common is by using hydrophones . Underwater communication is difficult due to factors such as multi-path propagation , time variations of the channel, small available bandwidth and ...
A 4-inch (100 mm) underwater locator beacon, with ballpoint pen for scale A ULB attached to a bracket on a cockpit voice recorder. An underwater locator beacon (ULB), underwater locating device (ULD), or underwater acoustic beacon is a device that emits an acoustic pulse intended to guide searchers equipped with a suitable receiver to the location of the beacon underwater.
GPS intelligent buoys (GIB) systems are inverted LBL devices where the transducers are replaced by floating buoys, self-positioned by GPS. The tracked position is calculated in realtime at the surface from the Time-Of-Arrival (TOAs) of the acoustic signals sent by the underwater device, and acquired by the buoys.
Output of a computer model of underwater acoustic propagation in a simplified ocean environment. A seafloor map produced by multibeam sonar. Underwater acoustics (also known as hydroacoustics) 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.
In telecommunications, a transponder is a device that, upon receiving a signal, emits a different signal in response. [1] The term is a blend of transmitter and responder . [ 2 ] [ 3 ]
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 communications satellite's transponder is the series of interconnected units that form a communications channel between the receiving and the transmitting antennas. [1] It is mainly used in satellite communication to transfer the received signals. A transponder is typically composed of: an input band-limiting device (an input band-pass filter),
These range measurements, which are often supplemented by depth data from pressure sensors on the devices, are then used to triangulate the position of the vehicle or diver. In figure 1, a diver mounted interrogator (A) sends a signal, which is received by the baseline transponders (B, C, D).