On Fri, 12 May 2006 21:34:14 -0700, Larry Jaques
wrote:

On Fri, 12 May 2006 15:23:03 -0500, with neither quill nor qualm, Don
Foreman quickly quoth:

On Fri, 12 May 2006 09:46:38 -0500, Rex B
wrote:

Larry Jaques wrote:

There are times I'd like to stake the owner to the yard for a day with
the barker a foot away from his ear. He might glean a new perspective,
I reckon.

Larry, if you figure out a solution to that problem, let me know.
I have the exact same problem behind me.

Hartmann whistle and a TV satellite dish. A Hartmann whistle can
produce extremely intense ultrasound -- 150 dB or so. 120 dB is
threshold of pain for humans. 150 dB is 1000 times the sound power
of 120 dB. A Hartmann whistle runs on compressed air, can be easily
made with a lathe and perhaps a couple of silverbrazed joints.
Instant canine headache at ranges probably as far as a barking dog
would be bothersome.

Excellent!


The wavelength of 22 KHz ultrasound is slightly shorter than Ka band
microwave, so beamwidth (and gain) will be even better with ultrasound
than it is with microwave from Ka band satellites. Beamwidth would be
about 1 degree half power included angle, , which is an "illuminated
region" of about 42" dia at 200 ft.

I wonder what the sound level would be at 1,000'. The offending pet is
across a 2 acre field, the RR tracks, and a street.

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.



The trick would be to discover where the device points, and then
put a sight on it for aiming at an actual target. A piezo tweeter
makes a pretty good ultrasound microphone for testing.

I have started to build one of these twice. The offending dog moved
away both times before I completed it. I still have the dish, though.

If you would like to build 3 (so you're never caught short again, the
NEXT time a mutt moves in) I'll see if Rex will go in with me to pay
your costs. I don't have a lathe yet, but do have a spare Dish Network
dish. What wavelength are those, anyway? (OoK, Wiki say "KU band.")

I think DirecTV is in the range of 12.2 to 12.7 GHz, lambda of about
1.8 cm or 0.72 in. 22 KHz ultrasound has lambda of 1.5 cm or 0.6 in,
pretty comparable.

I'm stacked with projects at the moment, but I'll put a Hartmann back
on the "ta do" list. Right now I'm trying to add electric drive to
my boat lift winch and "goin' to the lake" time is getting real close
even in MN. I'm adding some sprockets and adapting the motor and
planetary gear drive from a scrounged ATV winch. I'd rather push a
button than wind that 40" handwheel 40 revs with 20 lb of tangential
force every time I wanna go out for a little while. A commercial
gadget to do this runs over $500. I have about $10 in it so far, my
time is free. Unfortunately, my wife has figured out the "my time
is free" concept so there are plenty of honeydo projects.

I'm also welding up a "drop dolly" so I can roll a new 36" high (on
casters) tool chest under my 33" high bench.

Man, I bet there are a bunch of wet, cold walleye fishers out there
today for the opener, but they might well catch some fish with
weather as lousy as it is. They'll earn 'em!





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