Subject: Naval sound defense (weapons) New Scientist 8th Oct 05

one can only imagine what such a device would do to mammals in the area and for how far.
how many countries have torpedoes?, come on!

>
> From: Charles Lucy
>Subject: Naval sound defense (weapons) New Scientist 8th Oct 05
>
>
>Torpedo Zapper
>Enlarge image
>Torpedo Zapper
>
>THE US navy wants to protect its warships with a system that will >destroy incoming torpedoes by firing massive underwater shock waves >at them.
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>The ships would be equipped with arrays of 360 transducers each 1 >metre square - effectively big flat-panel loudspeakers - running >along either side of the hull below the waterline. When the ship's >sonar detects an incoming torpedo, the transducers simultaneously >fire an acoustic shock wave of such intensity that the torpedo either >detonates early or is disabled by the pulse's crushing force, >according to the Defence Advanced Research Projects Agency (DARPA), >which is funding the project.
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>But these are no ordinary loudspeakers: instead of having a >membranous diaphragm that can vibrate in response to a range of audio >frequencies, each of the devices has a ram-like cylindrical metal >armature at its centre. This is projected outwards by electromagnets >at very high speed, producing a shock wave. The array can be fired as >many times as needed.
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>When the six rows of 60 transducers on each side of the ship fire at >once, the cumulative action should generate a "destructive pressure >pulse capable of disabling an enemy's torpedo", according to DARPA.
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>Exactly how the system works is shrouded in military secrecy. But by >making a speaker several times larger than the wavelength of the >sound wave required, a tightly focused beam can be produced in front >of the speaker. This is because beam width is partly determined by >the aperture of the source - a bigger loudspeaker focuses sound in a >smaller area. (New Scientist, 9 September 2000, p 38). And the >combined size of the array makes for a very large speaker indeed. >This focusing would allow the array to precisely target incoming >torpedoes. In addition, the beam can be steered in different >directions - probably by slightly altering the phase of the applied >signals - a technique that is widely used to steer radio waves using >side-by-side antennas. So torpedoes homing in on the ship's wake from >many directions can be targeted (see Diagram).
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>So far, the system's developers, Anteon Technologies of Fairfax, >Virginia, and BAE Systems of Farnborough, UK, have only built one >transducer. But encouraged by software simulations that show the >array should work, they plan to press ahead with a one-quarter-scale >test rig.
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>If it reaches the stage of testing in the open ocean, however, the >developers are likely to come into conflict with marine biologists. >They have evidence that whales blasted by frequent acoustic signals >from submarine or ship sonar appear to develop symptoms of >decompression sickness, and die. (New Scientist, 11 October 2003, p 10).
>�The torpedo detonates early or is disabled by the pulse's crushing >force�
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>But neither DARPA, Anteon, nor BAE Systems was willing to respond to >questions about the array's proposed energy levels and any threat to >marine mammals they might pose.
> From issue 2520 of New Scientist magazine, 06 October 2005, page 32
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--
Kraig Grady
North American Embassy of Anaphoria Island <http://anaphoria.com/>
The Wandering Medicine Show
KXLU <http://www.kxlu.com/main.html> 88.9 FM Wed 8-9 pm Los Angeles

> one can only imagine what such a device would do to mammals
> in the area and for how far.

I hope they never make this thing, but I'm also worried about
the sonar they (and everyone) already have. I've never looked
into it, but it seems possible that it disrupts whale song.

> how many countries have torpedoes?, come on!

Seriously.

-Carl