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Detecting Ultrasound
Hi chaps,
I suspect a neighbour of a friend of mine is using an ultrasonic bird- scarer to frighten off his pets. The man concerned won´t admit to it, but there are times when his dog and two cats just seem to get suddenly very distressed and hypermanic for no apparent reason. I`d like to at least eliminate this possibility before considering any others. So the question is, what´s the simplest way to detect ultrasound? My web research leads me to believe the area of interest is between 20 and 30khz. Most common bird scarers warble between these two limits which are of course above the range of human hearing. I´ve acquired an ultrasonic transducer that transmits on 41khz. If I couple this up to a wien-bridge oscillator trimmed to the same frequency, I figure I ought to be able to hear a warble if indeed this guy is using a birdscarer, because the difference between 41khz and 20khz-30khz will be audible to me. Is this feasible to "air mix" the two frequencies in this simple way and hear a result, or is something more complicated required? Thanks! |
Detecting Ultrasound
wrote:
Hi chaps, I suspect a neighbour of a friend of mine is using an ultrasonic bird- scarer to frighten off his pets. The man concerned won´t admit to it, but there are times when his dog and two cats just seem to get suddenly very distressed and hypermanic for no apparent reason. I`d like to at least eliminate this possibility before considering any others. So the question is, what´s the simplest way to detect ultrasound? My web research leads me to believe the area of interest is between 20 and 30khz. Most common bird scarers warble between these two limits which are of course above the range of human hearing. I´ve acquired an ultrasonic transducer that transmits on 41khz. If I couple this up to a wien-bridge oscillator trimmed to the same frequency, I figure I ought to be able to hear a warble if indeed this guy is using a birdscarer, because the difference between 41khz and 20khz-30khz will be audible to me. Is this feasible to "air mix" the two frequencies in this simple way and hear a result, or is something more complicated required? Thanks! Interesting. The mixing process requires a non-linear device, which, for your purposes, I suspect the air is not. I've often considered, but never attempted, a similar mixing process using human ears (connected and intact, of course), since ears are quite non-linear. Ears won't work as mixers in your case since, at least for most adults, they are insensitive to ultrasonic frequencies (as well as to intelligent political analysis, it seems). The suggested bat detector is far more promising. Chuck ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
Detecting Ultrasound
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Detecting Ultrasound
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Detecting Ultrasound
On a sunny day (10 Mar 2007 05:18:34 -0800) it happened
wrote in .com: Hi chaps, Google 'bat detector'. |
Detecting Ultrasound
Stace MacGuyver wrote:
Suspend a thin shaving razor blade between two pieces of dental floss and put your ear close to the blade. Watch the razor vibrate. That's pretty cool, MacGuyver. Does the razor blade do anything? -- Martians drive SUVs! http://oregonmag.com/MarsWarm307.html |
Detecting Ultrasound
It cuts off your ear if you get too close ;)
clifto wrote: Stace MacGuyver wrote: Suspend a thin shaving razor blade between two pieces of dental floss and put your ear close to the blade. Watch the razor vibrate. That's pretty cool, MacGuyver. Does the razor blade do anything? |
Detecting Ultrasound
On Mar 10, 5:18�am, wrote:
Hi chaps, I suspect a neighbour of a friend of mine is using an ultrasonic bird- scarer to frighten off his pets. The man concerned won´t admit to it, but there are times when his dog and two cats just seem to get suddenly very distressed and hypermanic for no apparent reason. I`d like to at least eliminate this possibility before considering any others. So the question is, what´s the simplest way to detect ultrasound? My web research leads me to believe the area of interest is between 20 and 30khz. Most common bird scarers warble between these two limits which are of course above the range of human hearing. I´ve acquired an ultrasonic transducer that transmits on 41khz. If I couple this up to a wien-bridge oscillator trimmed to the same frequency, I figure I ought to be able to hear a warble if indeed this guy is using a birdscarer, because the difference between 41khz and 20khz-30khz will be audible to me. Is this feasible to "air mix" the two frequencies in this simple way and hear a result, or is something more complicated required? Thanks! The obvious "detection" would be oscilloscope observation of the amplified microphone signal. That's been mentioned. Some commercial ultrasound detectors simply heterodyne the ultrasonic range down to audible frequencies...good if your hearing goes on up to the high end of human response. Expensive as portable devices but easily genned up on the average home workbench. There are a couple of claims of outdoor advertising via sound through using high-power ultrasound generators in pairs, one modulated in amplitude the other unmodulated. The air acts as the non-linear "mixer" and the claim is that such beams of ultrasound can be focussed on particular locations. One such company is located in San Diego, California, if memory serves. 73, Len AF6AY |
Detecting Ultrasound
Scott wrote:
It cuts off your ear if you get too close ;) clifto wrote: Stace MacGuyver wrote: Suspend a thin shaving razor blade between two pieces of dental floss and put your ear close to the blade. Watch the razor vibrate. That's pretty cool, MacGuyver. Does the razor blade do anything? Be better if you could use it as an electric razor ... JS |
Detecting Ultrasound
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Detecting Ultrasound
John Smith I wrote:
Scott wrote: clifto wrote: Stace MacGuyver wrote: Suspend a thin shaving razor blade between two pieces of dental floss and put your ear close to the blade. Watch the razor vibrate. That's pretty cool, MacGuyver. Does the razor blade do anything? It cuts off your ear if you get too close ;) Be better if you could use it as an electric razor ... Replace the dental floss with Litz wire and attach ends to 110 VAC. Wait. Maybe not. Considering how many stations you can pick up with a razor-blade radio, that would probably interfere with vital communications all throughout the spectrum. What's the resonant frequency of a whisker? -- Martians drive SUVs! http://oregonmag.com/MarsWarm307.html |
Detecting Ultrasound
On Mar 10, 5:18 am, wrote:
Hi chaps, I suspect a neighbour of a friend of mine is using an ultrasonic bird- scarer to frighten off his pets. The man concerned won´t admit to it, but there are times when his dog and two cats just seem to get suddenly very distressed and hypermanic for no apparent reason. I`d like to at least eliminate this possibility before considering any others. So the question is, what´s the simplest way to detect ultrasound? My web research leads me to believe the area of interest is between 20 and 30khz. Most common bird scarers warble between these two limits which are of course above the range of human hearing. I´ve acquired an ultrasonic transducer that transmits on 41khz. If I couple this up to a wien-bridge oscillator trimmed to the same frequency, I figure I ought to be able to hear a warble if indeed this guy is using a birdscarer, because the difference between 41khz and 20khz-30khz will be audible to me. Is this feasible to "air mix" the two frequencies in this simple way and hear a result, or is something more complicated required? Thanks! You need your detector to be low Q since you don't know the offending frequency. Some of these fancy sound cards do 196kHz sampling. A piezo microphone with amp into the sound card might do the trick. Also, as other have suggest, the bat detector. |
Detecting Ultrasound
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Detecting Ultrasound
John Smith I wrote:
wrote: ... Do you really want to hear it, or have a "field strength indicator"/locater? Why not just a mike capable of "hearing" the ultrasonic freqs in question--feeding an opamp and meter? Pointing the mike around should lead you into the correct direction and following the meter reading should lead you to the source(s). Possibly can substitute a light or even a led in series with a pot and use a visual indication of strength ... JS Come to think of it, wouldn't take much more to square up the sine wave out of the opam and drop a cmos decade-divider onto that output of the opamp and feed an ear phone with the dividers output--30,000 becomes 3,000 hz--easily "hear-able!" JS |
Detecting Ultrasound
On 2007-03-10, John Smith I wrote:
John Smith I wrote: wrote: ... Do you really want to hear it, or have a "field strength indicator"/locater? Why not just a mike capable of "hearing" the ultrasonic freqs in question--feeding an opamp and meter? Pointing the mike around should lead you into the correct direction and following the meter reading should lead you to the source(s). Possibly can substitute a light or even a led in series with a pot and use a visual indication of strength ... JS Come to think of it, wouldn't take much more to square up the sine wave out of the opam and drop a cmos decade-divider onto that output of the opamp and feed an ear phone with the dividers output--30,000 becomes 3,000 hz--easily "hear-able!" only if theres no other sound present in the mic signal. and it will give no indication of signal amplitude. |
Detecting Ultrasound
On Sat, 10 Mar 2007 09:19:25 -0500, PeterD wrote:
Why worry about it... His yard, his pets, his life... I *think* what the OP is worried about is that his friends' pets are being scared off by his freinds' neighbor. While I hate to discourage anyone from building something electronic, I do have to ask: what will one do if they learn that a bird-scarer *is* in use? Best of my knowledge, they aren't illegal. If a bird-scarer works on dogs, then I find the details quite interesting. May have to work up a mobile version. Loose dogs allowed to roam a neighborhood are a serious safety issue for cyclists. (and I wonder if that's why the neighbor in question is trying to scare them off?) |
Detecting Ultrasound
clifto wrote:
John Smith I wrote: Scott wrote: clifto wrote: Stace MacGuyver wrote: Suspend a thin shaving razor blade between two pieces of dental floss and put your ear close to the blade. Watch the razor vibrate. That's pretty cool, MacGuyver. Does the razor blade do anything? It cuts off your ear if you get too close ;) Be better if you could use it as an electric razor ... Replace the dental floss with Litz wire and attach ends to 110 VAC. Wait. Maybe not. Considering how many stations you can pick up with a razor-blade radio, that would probably interfere with vital communications all throughout the spectrum. What's the resonant frequency of a whisker? They don't make the blue blades anymore. -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida |
Detecting Ultrasound
Michael A. Terrell wrote:
clifto wrote: John Smith I wrote: Scott wrote: clifto wrote: Stace MacGuyver wrote: Suspend a thin shaving razor blade between two pieces of dental floss and put your ear close to the blade. Watch the razor vibrate. That's pretty cool, MacGuyver. Does the razor blade do anything? It cuts off your ear if you get too close ;) Be better if you could use it as an electric razor ... Replace the dental floss with Litz wire and attach ends to 110 VAC. Wait. Maybe not. Considering how many stations you can pick up with a razor-blade radio, that would probably interfere with vital communications all throughout the spectrum. What's the resonant frequency of a whisker? They don't make the blue blades anymore. Do they make any other kind of thin shaving razor blades? -- Martians drive SUVs! http://oregonmag.com/MarsWarm307.html |
Detecting Ultrasound
clifto wrote:
Michael A. Terrell wrote: clifto wrote: John Smith I wrote: Scott wrote: clifto wrote: Stace MacGuyver wrote: Suspend a thin shaving razor blade between two pieces of dental floss and put your ear close to the blade. Watch the razor vibrate. That's pretty cool, MacGuyver. Does the razor blade do anything? It cuts off your ear if you get too close ;) Be better if you could use it as an electric razor ... Replace the dental floss with Litz wire and attach ends to 110 VAC. Wait. Maybe not. Considering how many stations you can pick up with a razor-blade radio, that would probably interfere with vital communications all throughout the spectrum. What's the resonant frequency of a whisker? They don't make the blue blades anymore. Do they make any other kind of thin shaving razor blades? Yes, but the blueing was what made a detector. -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida |
Detecting Ultrasound
On Tue, 13 Mar 2007 18:40:06 +0000, Michael A. Terrell wrote:
clifto wrote: Michael A. Terrell wrote: clifto wrote: John Smith I wrote: Scott wrote: clifto wrote: Stace MacGuyver wrote: Suspend a thin shaving razor blade between two pieces of dental floss and put your ear close to the blade. Watch the razor vibrate. I don't know how your sense organs are arranged, but I know that if I dangle something next to my ear, it's terribly hard to watch it simultaneously. ;-) That's pretty cool, MacGuyver. Does the razor blade do anything? It cuts off your ear if you get too close ;) Be better if you could use it as an electric razor ... Replace the dental floss with Litz wire and attach ends to 110 VAC. Wait. Maybe not. Considering how many stations you can pick up with a razor-blade radio, that would probably interfere with vital communications all throughout the spectrum. What's the resonant frequency of a whisker? They don't make the blue blades anymore. Do they make any other kind of thin shaving razor blades? Yes, but the blueing was what made a detector. What does that have to do with dangling the blade from dental floss? Or, for that matter, what does dangling a blade from dental floss even DO? Thanks, RIch |
Detecting Ultrasound
On Mar 10, 9:18 am, wrote:
Hi chaps, I suspect a neighbour of a friend of mine is using an ultrasonic bird- scarer to frighten off his pets. The man concerned won´t admit to it, but there are times when his dog and two cats just seem to get suddenly very distressed and hypermanic for no apparent reason. I`d like to at least eliminate this possibility before considering any others. So the question is, what´s the simplest way to detect ultrasound? My web research leads me to believe the area of interest is between 20 and 30khz. Most common bird scarers warble between these two limits which are of course above the range of human hearing. I´ve acquired an ultrasonic transducer that transmits on 41khz. If I couple this up to a wien-bridge oscillator trimmed to the same frequency, I figure I ought to be able to hear a warble if indeed this guy is using a birdscarer, because the difference between 41khz and 20khz-30khz will be audible to me. Is this feasible to "air mix" the two frequencies in this simple way and hear a result, or is something more complicated required? Thanks! If you want to compress the range of 0-30 kHz to something like 0-12 kHz you can do that with a switched capacitor delay chip like the Panasonic MN3007. It will work like the bat detector, except it won't need to clip and threshold the audio. You will need to use a slow ramped VCO (continually ramping the sampling frequency down) in order to do this. There are some projects at: http://www.geofex.com/ You may be able to adapt a flanger, for instance, to suit your purpose. The control voltage to the sampling VCO will be a sawtooth wave. Unfortunately, you will hear the sawtooth period as an artifact in the output. Maybe you can filter it out. I guess an all-digital solution is better ;-) Frank Raffaeli |
Detecting Ultrasound
Michael A. Terrell wrote:
clifto wrote: John Smith I wrote: Scott wrote: clifto wrote: Stace MacGuyver wrote: Suspend a thin shaving razor blade between two pieces of dental floss and put your ear close to the blade. Watch the razor vibrate. That's pretty cool, MacGuyver. Does the razor blade do anything? It cuts off your ear if you get too close ;) Be better if you could use it as an electric razor ... Replace the dental floss with Litz wire and attach ends to 110 VAC. Wait. Maybe not. Considering how many stations you can pick up with a razor-blade radio, that would probably interfere with vital communications all throughout the spectrum. What's the resonant frequency of a whisker? They don't make the blue blades anymore. Hmm. i was going to say, if it worked, it would be cutting edge technology! :) -- "I'm never wrong, once i thought i was, but was mistaken" Real Programmers Do things like this. http://webpages.charter.net/jamie_5 |
Detecting Ultrasound
Jamie wrote:
Michael A. Terrell wrote: clifto wrote: John Smith I wrote: Scott wrote: clifto wrote: Stace MacGuyver wrote: Suspend a thin shaving razor blade between two pieces of dental floss and put your ear close to the blade. Watch the razor vibrate. That's pretty cool, MacGuyver. Does the razor blade do anything? It cuts off your ear if you get too close ;) Be better if you could use it as an electric razor ... Replace the dental floss with Litz wire and attach ends to 110 VAC. Wait. Maybe not. Considering how many stations you can pick up with a razor-blade radio, that would probably interfere with vital communications all throughout the spectrum. What's the resonant frequency of a whisker? They don't make the blue blades anymore. Hmm. i was going to say, if it worked, it would be cutting edge technology! :) A sharp observation indeed. -- Martians drive SUVs! http://oregonmag.com/MarsWarm307.html |
Detecting Ultrasound
On a sunny day (Tue, 13 Mar 2007 22:42:58 GMT) it happened Rich Grise
wrote in : On Tue, 13 Mar 2007 18:40:06 +0000, Michael A. Terrell wrote: clifto wrote: Michael A. Terrell wrote: clifto wrote: John Smith I wrote: Scott wrote: clifto wrote: Stace MacGuyver wrote: Suspend a thin shaving razor blade between two pieces of dental floss and put your ear close to the blade. Watch the razor vibrate. I don't know how your sense organs are arranged, but I know that if I dangle something next to my ear, it's terribly hard to watch it simultaneously. ;-) Mirror, webcam, helper, |
Detecting Ultrasound
On Mar 11, 1:19 am, PeterD wrote:
On 10 Mar 2007 05:18:34 -0800, wrote: Hi chaps, I suspect a neighbour of a friend of mine is using an ultrasonic bird- scarer to frighten off his pets. The man concerned won´t admit to it, but there are times when his dog and two cats just seem to get suddenly very distressed and hypermanic for no apparent reason. I`d like to at least eliminate this possibility before considering any others. So the question is, what´s the simplest way to detect ultrasound? My web research leads me to believe the area of interest is between 20 and 30khz. Most common bird scarers warble between these two limits which are of course above the range of human hearing. I´ve acquired an ultrasonic transducer that transmits on 41khz. If I couple this up to a wien-bridge oscillator trimmed to the same frequency, I figure I ought to be able to hear a warble if indeed this guy is using a birdscarer, because the difference between 41khz and 20khz-30khz will be audible to me. Is this feasible to "air mix" the two frequencies in this simple way and hear a result, or is something more complicated required? Thanks! Why worry about it... His yard, his pets, his life... OK, Take a microphone with a frequency response 30Khz, and an amplifer. Monitor the amp's output with a scope. bg Agree. Even a bog standard electret for $1 will do it - probably wouldn't even need an amplifier......if you want to get sophisticated, put it in the end of a piece of 30mm plastic pipe - voila, directional microphone.... The alternative is you are just being paranoid......but I know you know that anyway... Andrew VK3BFA. |
Detecting Ultrasound
Jamie wrote:
Michael A. Terrell wrote: They don't make the blue blades anymore. Hmm. i was going to say, if it worked, it would be cutting edge technology! :) It was, a millennium ago. -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida |
Detecting Ultrasound
Do you know of any freq response curves on the web for the garden
variety electrets? I've looked and haven't found any. ==================== I found an Archer packaged (for Tandy) cat no 270-092B Electret Condenser Mike Element in its original Package, complete with response curve. From 30 - 3000 Hz the response is flat. From 3000 Hz to 5000 Hz the response increases by approx 10 dB. From 5000 - 9000 Hz the response drops such that it is back to its original level at 9000 Hz .Above that freq the response drops. Response curve is not extended beyond 12000 Hz Frank GM0CSZ / KN6WH |
Detecting Ultrasound
Andrew VK3BFA wrote:
Take a microphone with a frequency response 30Khz, and an amplifer. Monitor the amp's output with a scope. bg Agree. Even a bog standard electret for $1 will do it - probably wouldn't even need an amplifier......if you want to get sophisticated, put it in the end of a piece of 30mm plastic pipe - voila, directional microphone.... The alternative is you are just being paranoid......but I know you know that anyway... Andrew VK3BFA. Hello Andrew, Do you know of any freq response curves on the web for the garden variety electrets? I've looked and haven't found any. Thanks, Chuck NT3G ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
Detecting Ultrasound
wrote:
Hi chaps, I suspect a neighbour of a friend of mine is using an ultrasonic bird- scarer to frighten off his pets. The man concerned won=B4t admit to it, but there are times when his dog and two cats just seem to get suddenly very distressed and hypermanic for no apparent reason. I`d like to at least eliminate this possibility before considering any others. So the question is, what=B4s the simplest way to detect ultrasound? My web research leads me to believe the area of interest is between 20 and 30khz. Most common bird scarers warble between these two limits which are of course above the range of human hearing. I=B4ve acquired an ultrasonic transducer that transmits on 41khz. If I couple this up to a wien-bridge oscillator trimmed to the same frequency, I figure I ought to be able to hear a warble if indeed this guy is using a birdscarer, because the difference between 41khz and 20khz-30khz will be audible to me. Is this feasible to "air mix" the two frequencies in this simple way and hear a result, or is something more complicated required? Thanks! Google for 'bat detector'. -- Reply to nico@nctdevpuntnl (punt=.) Bedrijven en winkels vindt U op www.adresboekje.nl |
Detecting Ultrasound
On Sat, 10 Mar 2007 12:35:30 -0600, clifto wrote:
Stace MacGuyver wrote: Suspend a thin shaving razor blade between two pieces of dental floss and put your ear close to the blade. Watch the razor vibrate. That's pretty cool, MacGuyver. Does the razor blade do anything? Yes, it shaves your ear! |
Detecting Ultrasound
Try using a Motorola Peizo Tweeter. I think some are spec'd into
ultrasonic range. Highland Ham wrote: Do you know of any freq response curves on the web for the garden variety electrets? I've looked and haven't found any. ==================== I found an Archer packaged (for Tandy) cat no 270-092B Electret Condenser Mike Element in its original Package, complete with response curve. From 30 - 3000 Hz the response is flat. From 3000 Hz to 5000 Hz the response increases by approx 10 dB. From 5000 - 9000 Hz the response drops such that it is back to its original level at 9000 Hz .Above that freq the response drops. Response curve is not extended beyond 12000 Hz Frank GM0CSZ / KN6WH -- Joe Leikhim K4SAT "The RFI-EMI-GUY"© "Treason doth never prosper: what's the reason? For if it prosper, none dare call it treason." "Follow The Money" ;-P |
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