Ultrasonic

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What is it you're trying to accomplish? Are we trying to scatter birds and other pests? Transmission of digital information? Using multiple speakers to achieve a modulation effect where audible sound is only heard in a certain spot or spots? Distance measurement?

Chris

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Hi, Jim. And the most horrendously inhumane weapons ever actually used on the battlefield (mustard, phosgene gas) were used after the Hague Convention of 1907.

You're not talking to the expert, but I seem to remember that the First Protocol to the Fourth Geneva Convention (1977?) made mention of prohibiting the use of "inhumane" weapons, which are those that cause "superfluous injury or unnecessary suffering." I believe that's why U.S. troops can't use expanding rounds. Although I think NATO allows the use of rounds with a small hollow gas space in the tip, which has some of the effect of an expanding round.

No warranties or guarantees on these opinions, Jim. Just a slow day waiting for a customer to return a call.

Good luck Chris

Hello,

I am requesting help to construct an ultrasonic device that emits sound at about 25Khz. Unlike most ultrasonic devices, I want the device to carry sound over 100 feet (or 30 meters) and still be over 140 decibels at 100 feet (or 30 meters).

Does anyone know how I can do this? Plans? Actual devices? Please reply.

All I know of this is that the sirens on fire engines can do this for miles.

But for ultrasonic frequencies 140dB is supposed to vanish into nothing at about 20 feet. Is that correct?

reply.

miles.

I'd venture to say that many sirens have very low output in the ultrasonic range as they would be fairly useless as a warning device.

Look, a jet engine produces about 140 dB while a rock concert is about 115 dB. You need to check your figures...what you want isn't going to happen.

The "Rules of War" were put down in the Hague Convention. I don't know what the hang up with the Geneva Convention is, I guess it sticks in the mind better, BUT the Hague Convention puts forth that it is the incapacitation of an enemy that you should seek, not death in particular. Hence, the reason our armed forces are not allowed to use expanding rounds on human targets, just FMJ. SO, I would say a piss your pants ultra sound ray would fit right in with the Hague rules.

Jim

You will almost certainly need a highly focused system, with parabolic reflectors to direct the sound. It seems unlikely that you will have one small driver that can output the required excursion at 25 kHz. so you will need an array of drivers, with careful phase control to direct the beam. The whole thing will come down to how carefully you can get it focussed.

On the other hand, if you are looking for wide-area coverage, this is gonna take a lot of power!

Bob Masta dqatechATdaqartaDOTcom D A Q A R T A Data AcQuisition And Real-Time Analysis