Ultrasonics

[Bern1937]

I would like to send an ultrasonic signal 1000 feet. Is this possible, and if so what transducers would you suggest? If possible I would like to keep it low cost, as there will be several if this works. Thanks for any and all thoughts.

 

[Gryd3]

I would like to send an ultrasonic signal 1000 feet. Is this possible, and if so what transducers would you suggest? If possible I would like to keep it low cost, as there will be several if this works. Thanks for any and all thoughts.

Can you provide a little more info?
The ultrasonic signal... will it carry data? Or is this some kind of range-finder on steroids?
Is there a physical size limit?

 

[Bern1937]

Can you provide a little more info?
The ultrasonic signal... will it carry data? Or is this some kind of range-finder on steroids?
Is there a physical size limit?

 

[Bern1937]

No data per say, just an on/ off signal. Size is not critical, a couple square feet OK.

 

[KrisBlueNZ]

I would say not, though I can't show you any calculations to prove it. My reasons are (a) vibrations in air are absorbed and decay quite rapidly; (b) higher frequencies decay more rapidly than lower frequencies - because of the inertia of the atoms and molecules in the air, I guess; (c) vibrations in air cannot be focussed into a narrow beam; (d) even a light breeze will greatly affect the propagation of the sound. These are just ones that come to mind immediately.

Perhaps if you tell us what you want to do, instead of how you want to do it, we could suggest something.

 

[davenn]

I would be surprised to find one that could go 100ft let alone 1000ft

 

[Gryd3]

If it's just going to be on on/off signal, why are you stuck on Ultrasonic?
You could just as well do Light, or a different RF. (Unsure if this is line-of-sight only, or the environment requirements.)

 

[shumifan50]

Cheap hobbyist versions go about 5m when bounced off a hard surface (for range finder). Offhand this sounds like a job for a laser beam or a radio, but even those might battle if staying legal.

 

[Gryd3]

Cheap hobbyist versions go about 5m when bounced off a hard surface (for range finder). Offhand this sounds like a job for a laser beam or a radio, but even those might battle if staying legal.

Depending on the environment of course.
Line of sight communication would be easy and remain legal as you could use light or a parabolic dish to RF.
Other than that, things start to get much more difficult.

 

[Arouse1973]

I would like to send an ultrasonic signal 1000 feet. Is this possible, and if so what transducers would you suggest? If possible I would like to keep it low cost, as there will be several if this works. Thanks for any and all thoughts.

For 40KHz its about 40dB per 100 feet loss at 50% humidity and say 20 degrees. So you would need quite a transmitter.
Thanks Adam

 

[Vistec]

it sounds like he is trying to build a mice or rodent (animal) repellant

to cover an area of a cottage / house

or one of the units they use at shopping centers to keep teenagers from staying too long ( away )

 

[KrisBlueNZ]

it sounds like he is trying to build a mice or rodent (animal) repellant to cover an area of a cottage / house

A 1000 foot house? And in any case, ultrasonic "pest repellers" have never been demonstrated to be effective and are generally considered useless.

 

[(*steve*)]

For teenagers I would suggest Frank Sinatra. Not sure of the effect on rodents.

 

[BobK]

For teenagers I would suggest Frank Sinatra. Not sure of the effect on rodents.

Well, he was a member of the Rat Pack.

Bob