Description
develops linear and planar hydrophone arrays. The arrays are
designed to be applicable in passive SONAR for listening,
monitoring and direction-finding.
SONAR (
SOund
Navigation
And
Ranging) is a technique that uses sound
propagation (usually underwater, as in submarine navigation) to
navigate, communicate with or detect objects on or under the
surface of the water, such as other vessels and submarines. Two
types of technology share the name "sonar":
passive sonar
is essentially listening for the sound made by vessels;
active sonar is emitting pulses of sounds and listening
for echoes. The Sensing procedure in Sonar System usually is done
by Hydrophones.
A
hydrophone is a microphone designed to be used
underwater for recording or listening to underwater sounds. Most
hydrophones are based on a piezoelectric transducer that generates
electricity when subjected to a pressure change. Such piezoelectric
materials, or transducers, can convert a sound signal into an
electrical signal since sound is a pressure wave. The new
Technology of making Hydrophone is Acousto-Optic Transducer that
made by Fiber Optic Sensing Technology.
Fiber optic Hydrophones is one major type of hydrophones that are
of great importance to underwater and naval acoustics. The chief
advantage is that problems related to the integration of
traditional underwater acoustic sensing and sonar data transmission
can be resolved from an entirely new perspective, thus improving
the reliability and possibly decreasing the total cost of
manufacture, operation and maintenance of the sonar system.
Because of its inherent directivity and unique phase processing,
the Fiber Optic (FO) hydrophone possesses potential advantages in
the detection of quiet underwater acoustic targets emitting low
frequency and ultra-low frequency noise. Engineering applications
for FO hydrophone have gradually emerged from the research
laboratory, and will play an active role in the development of
future sonar systems. A brief overview of the two technology
(Piezoelectric and Fiber Optic) is presented from the viewpoint of
sonar design, including the basic physics, principle of operation,
key techniques, and applications.
