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(Redirected from Hydrophones)
A 'hydrophone' is a sound-to-electricity transducer for use in water or other liquids, analogous to a ear for listening to underwater sound. Such a transducer can sometimes also serve as a projector (emitter), but not all have this capability, and may be destroyed if used in such a manner.

Contents

History

Directional hydrophones

Focused Transducers

Arrays

Geophysics

References

Links

History

Directional hydrophones

A small single cylindrical ceramic transducer can achieve near perfect omnidirectional reception. Directional hydrophones increase sensitivity from one direction using two basic techniques:

Focused Transducers

This device uses a single transducer element with a dish or conical-shaped sound reflector to focus the signals, in a similar manner to a reflecting telescope. This type of hydrophone can be produced from a low-cost omnidirectional type, but must be used while stationary, as the reflector impedes its movement through water.

Arrays

Multiple hydrophones can be arranged in an array so that it will add the signals from the desired direction while subtracting signals from other directions. The array may be steered using a beamformer. Most commonly, hydrophones are arranged in a "line array" but may be in two or three dimensional arrangements.

Geophysics

Geophones are a low frequency form of hydrophone used by geologists and geophysicists in detecting seismic energy. They are combined to form streamers that are towed by seismic vessels or deployed in a borehole.

References

★ Pike, John (1999). SOSUS Retrieved Jan. 28, 2005.

★ Watlington, Frank (1979). ''How to build & use low-cost hydrophones.'' (ISBN 0830610790)

★ Unknown. hydrophone Retrieved Jan. 28, 2005.

★ Unknown. (2005) Schlumberger Oilfield Glossary: Term 'hydrophone' Retrieved Jan. 28, 2005.

Links

★ Passive Acoustic Monitoring

★ www.sml-uk.co.uk/index.htm

★ www.geocet.com