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.
 
"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).
Click to expand...
It would help if you were to describe the medium,
intended signal reaching the target(s), duty cycle,
and the general purpose of your device.

Does anyone know how I can do this? Plans? Actual devices? Please reply.
Click to expand...
Your main challenge is going to be transducer design.
This is probably not right forum for help with that.

All I know of this is that the sirens on fire engines can do this for miles.
Click to expand...
They do not.

--
--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.
 
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).
Click to expand...

140dB at 100 feet????

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

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).
Click to expand...
I will assume you mean dBA SPL, not dB. The Decibel is a ratio,
not an absolute quantity. What you wrote above translates to
"I want the device to ... be 30,000 times louder than at 100
feet." 30,000 times louder than what?

All I know of this is that the sirens on fire engines can
do this for miles.
Click to expand...
In that case, you have a big problem. The one thing that you think
you know is completely false. A typical 100 watt fire engine siren
puts out 130 dBA at 1 meter on axis. To get that up to 140 dBA at
1 meter would take a 10,000 watt speaker (+10 dBa is x10 power and
x2 perceived loudness).

Sound pressure levels in a free field from a point source decrease
6 dB for each distance doubling. So to increase that 10 kW 140
dBA enough to reach that level at 30 meters instead of 1 meter,
you would need these levels:

1 meter 170 dBA
2 meters 164 dBA
4 meters 158 dBA
8 meters 152 dBA
16 meters 146 dBA
32 meters 140 dBA

....and your 140 dBA 10,000 Watt speaker would have to be
replaced with a 170dBa 10,000,000,000 Watt speaker.

So, do you happen to have a 10 billion watt power amplifier
laying about that you can use to drive this speaker?

Now let's talk abhout the fence you will need to build.
Federal maximum exposure standards are:

90 dBA Sound Pressure Level for eight hours, or
95 dBA Sound Pressure Level for four hours, or
100 dBA Sound Pressure Level for two hours, or
105 dBA Sound Pressure Level for one hour, or
110 dBA Sound Pressure Level for 30 minutes, or
115 dBA Sound Pressure Level for 15 minutes, or
120 dBA Sound Pressure Level for 7 minutes

You need to move the fence twice as far to get each
6 dB of noise reduction, so the fence will be:

32 meters away from the speaker for 140 dBa exposure.
64 meters away from the speaker for 132 dBa exposure.
128 meters away from the speaker for 128 dBa exposure.
256 meters away from the speaker for 122 dBa exposure.
512 meters away from the speaker for 116 dBa exposure.
1 kilometer away from the speaker for 104 dBa exposure.
2 kilometers from the speaker for 98 dBa exposure.
4 kilometers from the speaker for 92 dBa exposure.
8 kilometers from the speaker for 86 dBa exposure.
That's a circle 16 km across.

I have a suggestion. Why don't you tell us what you are
trying to accomplish rather than asking us to help you to
implement the "solution" that you came up with on your own?

--
Guy Macon <http://www.guymacon.com/>

(Note: every Usenet post that contains calculations is required
by law to have at least one typo or bonehead math error...)
 
Mark Jones wrote:

140dB at 100 feet????

This comes close: 138dB at 100 feet:
http://www.victorysiren.com/x/
Click to expand...
This shows the power of a good design. What I calculated to
require 10 billion watts using speakers and amplifiers only
took 100,000 watts (180hp) using compressed air and a rotor.

does anyone know why they are specing 10dB loss per distance
doubling rather than 6dB?
 
I read in sci.electronics.design that Guy Macon
<http@?.guymacon.com/.invalid> wrote (in
<115b2ospm074p82@corp.supernews.com>) about 'Ultrasonic', on Thu, 7 Apr
2005:

A typical 100 watt fire engine siren puts out 130 dBA at 1 meter on
axis. To get that up to 140 dBA at 1 meter would take a 10,000 watt
speaker (+10 dBa is x10 power and x2 perceived loudness).
Click to expand...
As you so presciently stated:

(Note: every Usenet post that contains calculations is required
by law to have at least one typo or bonehead math error...)

--
Regards, John Woodgate, OOO - Own Opinions Only.
There are two sides to every question, except
'What is a Moebius strip?'
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
 
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).


It would help if you were to describe the medium,
intended signal reaching the target(s), duty cycle,
and the general purpose of your device.


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


Your main challenge is going to be transducer design.
This is probably not right forum for help with that.
Click to expand...
I suspect your main challenge is gonna be using the telephone after
your first test experiment. The good news is that your life
will be very quiet from then on...
mike

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


They do not.
Click to expand...


--
Return address is VALID but some sites block emails
with links. Delete this sig when replying.
..
Wanted, PCMCIA SCSI Card for HP m820 CDRW.
FS 500MHz Tek DSOscilloscope TDS540 Make Offer
Wanted, 12.1" LCD for Gateway Solo 5300. Samsung LT121SU-121
Wanted 13" LCD for Mitac 6133 Samsung HT13X13-201
Bunch of stuff For Sale and Wanted at the link below.
MAKE THE OBVIOUS CHANGES TO THE LINK
ht<removethis>tp://www.geocities.com/SiliconValley/Monitor/4710/
 
(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/
Click to expand...
Yep, close. Overlooking that the OP means dbA,
all he needs to do is get that 3 ton device shipped
to his place, drive it about 30 to 80 times faster
with something better than its 180 HP engine, and
stand back if he has any sense, (not to be assumed).

--
--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.
 
"Guy Macon" <http://www.guymacon.com/> wrote in message
news:115b3fb8v7qg788@corp.supernews.com...
does anyone know why they are specing 10dB loss per distance
doubling rather than 6dB?
Click to expand...
Absorbtion, reflection, etc. by the buildings, foiliage, etc. along the way?

Back in antenna school it was discussed how, while power in free space
should drop off as 1/r^2, for practical purposes a value between 1/r^2 and
1/r^3 was used, with 1/r^2.5 not being uncommon. That gets
you -8dB/doubling... I imagine with sound waves similar approaches are
used.
 
"Guy Macon" <http://www.guymacon.com/> wrote in message
news:115b2ospm074p82@corp.supernews.com...
Korben Dallas wrote:

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).

I will assume you mean dBA SPL, not dB. The Decibel is a ratio,
not an absolute quantity. What you wrote above translates to
"I want the device to ... be 30,000 times louder than at 100
feet." 30,000 times louder than what?
Click to expand...
As Mr. Pefhany has helped me realize in sci.electronics.basics,
the Decibel is also used for sound pressure levels, with the 0 dB
reference point being 20 uPa. The dBA (and dBC) reference
levels follow a function determined by perception among humans,
and are not defined above the audio range. So the OP may well
have meant "dB". (I agree that bare "dB" should be cast out of
our lexicon for absolute measurents, but it's not up to us.)

[Uncontested material cut.]

--
--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.
 
I read in sci.electronics.design that Guy Macon
<http@?.guymacon.com/.invalid> wrote (in
<115b3fb8v7qg788@corp.supernews.com>) about 'Ultrasonic', on Thu, 7 Apr
2005:
does anyone know why they are specing 10dB loss per distance doubling
rather than 6dB?
Click to expand...
When they measured it, it was facing into the wind. Maybe.
--
Regards, John Woodgate, OOO - Own Opinions Only.
There are two sides to every question, except
'What is a Moebius strip?'
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
 
On Thu, 07 Apr 2005 19:33:27 +0000, Guy Macon
<http://www.guymacon.com/> wrote:

Korben Dallas wrote:

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).

I will assume you mean dBA SPL, not dB. The Decibel is a ratio,
not an absolute quantity. What you wrote above translates to
"I want the device to ... be 30,000 times louder than at 100
feet." 30,000 times louder than what?

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

In that case, you have a big problem. The one thing that you think
you know is completely false. A typical 100 watt fire engine siren
puts out 130 dBA at 1 meter on axis. To get that up to 140 dBA at
1 meter would take a 10,000 watt speaker (+10 dBa is x10 power and
x2 perceived loudness).

Sound pressure levels in a free field from a point source decrease
6 dB for each distance doubling. So to increase that 10 kW 140
dBA enough to reach that level at 30 meters instead of 1 meter,
you would need these levels:

1 meter 170 dBA
2 meters 164 dBA
4 meters 158 dBA
8 meters 152 dBA
16 meters 146 dBA
32 meters 140 dBA

...and your 140 dBA 10,000 Watt speaker would have to be
replaced with a 170dBa 10,000,000,000 Watt speaker.

So, do you happen to have a 10 billion watt power amplifier
laying about that you can use to drive this speaker?

Now let's talk abhout the fence you will need to build.
Federal maximum exposure standards are:

90 dBA Sound Pressure Level for eight hours, or
95 dBA Sound Pressure Level for four hours, or
100 dBA Sound Pressure Level for two hours, or
105 dBA Sound Pressure Level for one hour, or
110 dBA Sound Pressure Level for 30 minutes, or
115 dBA Sound Pressure Level for 15 minutes, or
120 dBA Sound Pressure Level for 7 minutes

You need to move the fence twice as far to get each
6 dB of noise reduction, so the fence will be:

32 meters away from the speaker for 140 dBa exposure.
64 meters away from the speaker for 132 dBa exposure.
128 meters away from the speaker for 128 dBa exposure.
256 meters away from the speaker for 122 dBa exposure.
512 meters away from the speaker for 116 dBa exposure.
1 kilometer away from the speaker for 104 dBa exposure.
2 kilometers from the speaker for 98 dBa exposure.
4 kilometers from the speaker for 92 dBa exposure.
8 kilometers from the speaker for 86 dBa exposure.
That's a circle 16 km across.

I have a suggestion. Why don't you tell us what you are
trying to accomplish rather than asking us to help you to
implement the "solution" that you came up with on your own?
Click to expand...
Don't forget to add in absorption. That will amount to about 15dB/30m,
depending on humidity, temp, and other factors.

Mark
 
Looks like the guy in original posting is looking (dreaming) to build sonic
weapon.
Like American Technology Corp
http://www.atcsd.com/

The premise is that at above 140 db air becomes unlinear media for acoustic.
Hence, if Ultrasound is modulated by audial frequency it becomes demodulated
on non-linearity.

I yet to hear about success of this weapon. I heard trial units were sent in
Iraq, ... and did not hear et how it helped American soldiers.

Andrey

"Guy Macon" <http://www.guymacon.com/> wrote in message
news:115b2ospm074p82@corp.supernews.com...
Korben Dallas wrote:

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).

I will assume you mean dBA SPL, not dB. The Decibel is a ratio,
not an absolute quantity. What you wrote above translates to
"I want the device to ... be 30,000 times louder than at 100
feet." 30,000 times louder than what?

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

In that case, you have a big problem. The one thing that you think
you know is completely false. A typical 100 watt fire engine siren
puts out 130 dBA at 1 meter on axis. To get that up to 140 dBA at
1 meter would take a 10,000 watt speaker (+10 dBa is x10 power and
x2 perceived loudness).

Sound pressure levels in a free field from a point source decrease
6 dB for each distance doubling. So to increase that 10 kW 140
dBA enough to reach that level at 30 meters instead of 1 meter,
you would need these levels:

1 meter 170 dBA
2 meters 164 dBA
4 meters 158 dBA
8 meters 152 dBA
16 meters 146 dBA
32 meters 140 dBA

...and your 140 dBA 10,000 Watt speaker would have to be
replaced with a 170dBa 10,000,000,000 Watt speaker.

So, do you happen to have a 10 billion watt power amplifier
laying about that you can use to drive this speaker?

Now let's talk abhout the fence you will need to build.
Federal maximum exposure standards are:

90 dBA Sound Pressure Level for eight hours, or
95 dBA Sound Pressure Level for four hours, or
100 dBA Sound Pressure Level for two hours, or
105 dBA Sound Pressure Level for one hour, or
110 dBA Sound Pressure Level for 30 minutes, or
115 dBA Sound Pressure Level for 15 minutes, or
120 dBA Sound Pressure Level for 7 minutes

You need to move the fence twice as far to get each
6 dB of noise reduction, so the fence will be:

32 meters away from the speaker for 140 dBa exposure.
64 meters away from the speaker for 132 dBa exposure.
128 meters away from the speaker for 128 dBa exposure.
256 meters away from the speaker for 122 dBa exposure.
512 meters away from the speaker for 116 dBa exposure.
1 kilometer away from the speaker for 104 dBa exposure.
2 kilometers from the speaker for 98 dBa exposure.
4 kilometers from the speaker for 92 dBa exposure.
8 kilometers from the speaker for 86 dBa exposure.
That's a circle 16 km across.

I have a suggestion. Why don't you tell us what you are
trying to accomplish rather than asking us to help you to
implement the "solution" that you came up with on your own?

--
Guy Macon <http://www.guymacon.com/

(Note: every Usenet post that contains calculations is required
by law to have at least one typo or bonehead math error...)
Click to expand...
 
Andrey wrote:

I yet to hear about success of this weapon. I heard trial units were sent in
Iraq, ... and did not hear et how it helped American soldiers.

Andrey
Click to expand...
WHAT.....WHAT....DID.....YOU.....SAY.........

WHY CAN'T THESE OLD PEOPLE SPEAK UP.
 
From deep down memory I seem to recall it has to do with the fact that
a perceived (audible) doubling (or halving) of sound level corresponds
to a 10dB change. In real power terms the same change is only 6dB.


On Thu, 07 Apr 2005 19:45:27 +0000, Guy Macon
<http://www.guymacon.com/> wrote:

Mark Jones wrote:

140dB at 100 feet????

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

This shows the power of a good design. What I calculated to
require 10 billion watts using speakers and amplifiers only
took 100,000 watts (180hp) using compressed air and a rotor.

does anyone know why they are specing 10dB loss per distance
doubling rather than 6dB?
Click to expand...
 
Larry Brasfield wrote:

As Mr. Pefhany has helped me realize in sci.electronics.basics,
the Decibel is also used for sound pressure levels, with the 0 dB
reference point being 20 uPa.
Click to expand...
Thanks! I was not aware of that.
 
John Woodgate wrote:

As you so presciently stated:

(Note: every Usenet post that contains calculations is required
by law to have at least one typo or bonehead math error...)
Click to expand...
Hey, what's a x10 typo between friends? A billion watts,
ten billion watts, 100 billion watts, who cares? It's just
an added zero, and what is a zero, really? Nothing!

:)
 
In message <115cj919d69ovbf@corp.supernews.com>, Guy Macon
<_see.web.page_@_www.guymacon.com_> writes
John Woodgate wrote:

As you so presciently stated:

(Note: every Usenet post that contains calculations is required
by law to have at least one typo or bonehead math error...)

Hey, what's a x10 typo between friends? A billion watts,
ten billion watts, 100 billion watts, who cares? It's just
an added zero, and what is a zero, really? Nothing!

:)
Click to expand...
Irrespective of how many zeros there are, if you could generate that SPL
and focus it using a parabolic reflector to produce a plane wave, then
apart from acoustic damping in the air it should be the same at any
distance.

I know reality never works quite the same as the theoretical model but
140 dB relative to 20 uPa at 30 m might be achievable.

We're going to have to get something done about reality. It messes up so
many brilliant designs.
--
Graham
 
On Thu, 07 Apr 2005 19:45:27 +0000, Guy Macon wrote:
Mark Jones wrote:

140dB at 100 feet????

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

This shows the power of a good design. What I calculated to require 10
billion watts using speakers and amplifiers only took 100,000 watts
(180hp) using compressed air and a rotor.

does anyone know why they are specing 10dB loss per distance doubling
rather than 6dB?
Click to expand...
Probably ground clutter.

Cheers!
Rich
 
On Fri, 08 Apr 2005 13:49:49 +0000, Graham Orme wrote:
In message <115cj919d69ovbf@corp.supernews.com>, Guy Macon
John Woodgate wrote:

As you so presciently stated:

(Note: every Usenet post that contains calculations is required by law
to have at least one typo or bonehead math error...)

Hey, what's a x10 typo between friends? A billion watts, ten billion
watts, 100 billion watts, who cares? It's just an added zero, and what
is a zero, really? Nothing!
Click to expand...
A billion here, a billion there, and pretty soon you're talking real
money!

Irrespective of how many zeros there are, if you could generate that SPL
and focus it using a parabolic reflector to produce a plane wave, then
apart from acoustic damping in the air it should be the same at any
distance.

I know reality never works quite the same as the theoretical model but
140 dB relative to 20 uPa at 30 m might be achievable.

We're going to have to get something done about reality. It messes up so
many brilliant designs.
Click to expand...
I wonder what they guy's trying to do? Shoot down flying saucers?

Cheers!
Rich
 
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