Ultrasonic

K

Korben Dallas

Guest
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.
 
140dB at 100 feet is as loud as a commercial airplane jet engine.
Click to expand...

But for ultrasonic frequencies 140dB is supposed to vanish into nothing at
about 20 feet. Is that correct?
 
"Korben Dallas" <no@spam.com> wrote in message
news:gme5e.51931$cg1.32575@bgtnsc04-news.ops.worldnet.att.net...
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.
Click to expand...


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.
 
In article <1112897255.495007.241480@o13g2000cwo.googlegroups.com>,
cfoley1064@yahoo.com says...
Korben Dallas wrote:
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.


Is this a military contract or anti-personnel weapon? If so, I believe
this would be in violation of the Geneva Convention's requirements.
Most nations are signatories. My understanding is that it's considered
humane to make weapons whose purpose is to kill, but inhumane to make
weapons whose sole purpose is to maim or disfigure. ;-)

140dB at 100 feet is as loud as a commercial airplane jet engine.

Possibly you'd want to check your SPL knowledge. Look at these:

http://www.nidcd.nih.gov/health/education/decibel/decibel_text.asp
http://www.gcaudio.com/resources/howtos/loudness.html

Chris


The "Rules of War" were put down in the Hague Convention.
Click to expand...
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

http://www.lib.byu.edu/%7Erdh/wwi/hague/hague5.html
 
On Thu, 7 Apr 2005 12:52:10 -0700, the renowned "Larry Brasfield"
<donotspam_larry_brasfield@hotmail.com> wrote:

(Followups set to sci.electronics.basics where this
was inappropriately multi-posted by the OP.)

"Mark Jones" <abuse@127.0.0.1> wrote in message
news:5pydnd48mvW6F8jfRVn-hA@buckeye-express.com...
Larry Brasfield wrote:
"Korben Dallas" <no@spam.com> wrote in message
news:0me5e.51921$cg1.17447@bgtnsc04-news.ops.worldnet.att.net...

Hello,

Hi.

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).



140dB at 100 feet????

This comes close: 138dB at 100 feet:
http://www.victorysiren.com/x/

Yep, close. Overlooking that the OP means dbA,
Click to expand...
How do you know it's not dBC ?


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
 
"Spehro Pefhany" <speffSNIP@interlogDOTyou.knowwhat> wrote in
message news:m54b515gvf8eidt5o8n2lcvrgnmshhvtn6@4ax.com...
On Thu, 7 Apr 2005 12:52:10 -0700, the renowned "Larry Brasfield"
donotspam_larry_brasfield@hotmail.com> wrote:
....
Overlooking that the OP means dbA,

How do you know it's not dBC ?
Click to expand...

I don't, of course. Just a guess since dBA is
more commonly used. But since dBA and dBC
are both perception weighted functions, adapted
to human hearing, and the OP wants 25 KHz,
(past where humans hear and beyond where the
perception weighted filters are defined), I suppose
the OP may well mean plain "dB", where the
reference is 20 uPa of peak sound pressure.

I suspect it won't matter when all is said and done.

--
--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.
 
On Thu, 07 Apr 2005 18:35:05 GMT, "Korben Dallas" <no@spam.com> wrote:

140dB at 100 feet is as loud as a commercial airplane jet engine.


But for ultrasonic frequencies 140dB is supposed to vanish into nothing at
about 20 feet. Is that correct?
Click to expand...
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
www.daqarta.com
 
Korben Dallas wrote:
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.
Click to expand...


Is this a military contract or anti-personnel weapon? If so, I believe
this would be in violation of the Geneva Convention's requirements.
Most nations are signatories. My understanding is that it's considered
humane to make weapons whose purpose is to kill, but inhumane to make
weapons whose sole purpose is to maim or disfigure. ;-)

140dB at 100 feet is as loud as a commercial airplane jet engine.

Possibly you'd want to check your SPL knowledge. Look at these:

http://www.nidcd.nih.gov/health/education/decibel/decibel_text.asp
http://www.gcaudio.com/resources/howtos/loudness.html

Chris
 
Korben Dallas wrote:
140dB at 100 feet is as loud as a commercial airplane jet engine.


But for ultrasonic frequencies 140dB is supposed to vanish into
nothing at
about 20 feet. Is that correct?
Click to expand...
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
 
James Beck wrote:
In article <1112897255.495007.241480@o13g2000cwo.googlegroups.com>,
cfoley1064@yahoo.com says...
Is this a military contract or anti-personnel weapon? If so, I
believe
this would be in violation of the Geneva Convention's requirements.
Most nations are signatories. My understanding is that it's
considered
humane to make weapons whose purpose is to kill, but inhumane to
make
weapons whose sole purpose is to maim or disfigure. ;-)

140dB at 100 feet is as loud as a commercial airplane jet engine.

Possibly you'd want to check your SPL knowledge. Look at these:

http://www.nidcd.nih.gov/health/education/decibel/decibel_text.asp
http://www.gcaudio.com/resources/howtos/loudness.html

Chris


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

http://www.lib.byu.edu/%7Erdh/wwi/hague/hague5.html
Click to expand...
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
 
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