Sonar Inspired by Dolphins: New Kind of Underwater Device Can Detect Objects Through Bubble Clouds
ScienceDaily (Nov. 18, 2010) — Scientists at the University of Southampton have developed a new kind of underwater sonar device that can detect objects through bubble clouds that would effectively blind standard sonar.
Tim Leighton with dolphin. (Credit: Image courtesy of National Oceanography Centre, Southampton (UK))
Just as ultrasound is used in medical imaging, conventional sonar 'sees' with sound. It uses differences between emitted sound pulses and their echoes to detect and identify targets. These include submerged structures such as reefs and wrecks, and objects, including submarines and fish shoals.
However, standard sonar does not cope well with bubble clouds resulting from breaking waves or other causes, which scatter sound and clutter the sonar image.
Professor Timothy Leighton of the University of Southampton's Institute of Soundand Vibration Research (ISVR), who led the research, explained:
"Cold War sonar was developed mainly for use in deep water where bubbles are not much of a problem, but many of today's applications involve shallow waters. Better detection and classification of targets in bubbly waters are key goals of shallow-water sonar."
...
Read more here/Leia mais aqui: Science Daily
+++++
Clutter suppression and classification using twin inverted pulse sonar (TWIPS)
T. G. Leighton1,*, D. C. Finfer1, P. R. White1, G.-H. Chua1 and J. K. Dix2
+Author Affiliations
1Institute of Sound and Vibration Research, University of Southampton, Highfield, Southampton SO17 1BJ, UK
2School of Ocean and Earth Sciences, University of Southampton, National Oceanography Centre, Southampton, European Way, Southampton SO14 3ZH, UK
*Author for correspondence (tgl@soton.ac.uk).
Abstract
This paper describes the detection and classification of targets against clutter by distinguishing between linear and nonlinear scatterers and, further, by distinguishing those nonlinear targets that scatter energy at the even-powered harmonics from those that scatter in the odd-powered harmonics. This is done using twin inverted pulse sonar (TWIPS), which can also, in some manifestations, require no range correction (and therefore does not require the a priori knowledge of the environment needed for most remote detection technologies). The method applies, in principle, to a range of sensor technologies, including the use of radar to distinguish between circuitry, metal and soil; Light Detection and Ranging (LIDAR) to detect combustion products; and Magnetic Resonance Imaging (MRI). A sonar application is demonstrated, detecting objects in bubbly water (including in the wake of a ship of 3953 gross register tonnage). A man-made sonar that can operate in bubbly water is relevant: Cold War sonar is not optimized for the shallow coastal waters that typify many current operations. The US Navy use dolphins in such waters. TWIPS arose as a demonstration that echolocation was possible in bubbly water in response to a video showing dolphins generating bubble nets when hunting: if echolocation were impossible in these nets, then during this hunt, the dolphins would have blinded their sonar.
acoustics, bubbles, wakes, dolphins, sonar, radar
Received March 18, 2010.
Accepted May 4, 2010.
© 2010 The Royal Society
+++++
