"Don Foreman" wrote in message
...
On Sun, 14 May 2006 17:49:36 GMT, Gunner
wrote:

On Sun, 14 May 2006 10:46:12 -0500, Don Foreman
wrote:

On Sat, 13 May 2006 20:20:48 -0700, Larry Jaques
wrote:

On Sat, 13 May 2006 12:09:29 -0500, with neither quill nor qualm, Don
Foreman quickly quoth:

I think atmospheric absorption might be excessive at much over 200
feet. Massa's book on Ultrasonics may have charts, if I can find it
in the basement.

Danke.

The reference I have is a bit inconclusive, but it looks like 1000
feet might not be out of the question in terms of atmospheric
absorption of 22 KHz ultrasound. There would definitely be some
loss, maybe 10 to 20 dB. Things were still being learned when my
rather old reference ('40s or 50's) was written.

This absorption is in addition to R-squared loss, which could be
dealt with by using a larger dish to get a tighter beam.

Hartmann whistles can produce ultrasound intense enough to boil
water and kill mice when focussed at short range, so some loss is
sustainable.

I wouldn't think a barking dog 1000 feet away would be that onerous,
but your hearing is probably considerably more acute than mine.



Or simply install a microphone at the property line, that every bark
triggers a sonic blast. of several seconds duration.

I think that'd be nearly essential, so the dog will learn to
associate "ARF" with immediate "OW!" The objective is training
rather than retribution.

Now it would be fun if that sonic blast could be heard by the owners.
Everytime the dog barks..the owners get it.

Merely a matter of tuning! Given that very few loudspeakers deliver
5% efficiency (watts of sound power per electrical watt), it'd be
about equivalent to several kilowatts of ARF. (Followed by human OW!)
Kinda poetic: arf....ARRRF...OW! We could call it the Arfarrfow.

In actuality, since females tend to have better high-frequency acuity
it might be more like arf...ARRRFF ...HARRY, GODDAMMIT, MAKE THAT
STUPID DOG SHUT UP!!!

You may recall the story of Richard The ****, who was messing up my
4th of July evening tryst with his poppity poppity firecrackers.
Finally, about 10:30, I figured RTS should be in bed or inside playing
with his nintendo or something so I put a 1 gallon O/A baggiebombe
with a Winston time-delay fuse by the fence.

Poppity poppity KERBLAM ......RICHARD, GETCHERASSINHERE NOW!
Shortly later there were some blue flashing lights in the next
street for a few minutes, then all was blissfully peaceful.


We did that one year on our hillside very rural home, but we used a 55
gallon drum, a spark plug, a tbsp. of gasoline, and pure O2. Lucky for us,
there was a delay until the blue lights actually got there, and we were able
to find MOST of the barrel.

When they asked if we had seen or heard anything, all we could answer was,

"Huh?"

Steve