Producing ultra-sound with a frequency range between 100kHz - 200kHz? - Page 1
Forum section: electronics / projects

author: David_
author_rank: Contributor
timestamp: August 23, 2019, 02:43:12 am
content: Hello.I want to somehow create/generate ultra-sound with a frequency rang that exceeds 100kHz, generating sine- or square-waves of such frequencies as a electrical signal is obviously not a problem but how would I go about translating such signals into actual sound-waves?Ordinary speakers, even the fanciest of the high-end speakers wouldn't as far as I know be able to come even close to 100kHz and I do know that there are ultra-sound transmitters but AFAIK they produce ultra-sound at pretty much a fixed frequency, so I though that I should open a thread here to see if anyone here knows about some way of achieving this.Would it be possible/feasible to use a range of ultra-sound transmitters covering the frequency range of interest?This is really experimental so I can't clearly specify a range but 100kHz - 200kHz would be a good start.Are there ultra-sound transmitters which outputs frequencies that may be altered or adjusted?I have been thinking about this for some weeks now and I can't come up with anything other than ultra-sound transmitters with fixed frequency and using a larger number of them, switching between them to produce ultra-sound with frequencies that increase in steps, the steps being decided by what sort of choices there are for ultra-sound transmitters. But from what I have found online(mind you I know nothing about this area of technology) there is transmitters available with a output frequency of around 143 kHz or something like that, but I really need to be able to have the ability to create a range of individual frequencies one at a time.Any and all ideas are welcome, do I want to do something that is even possible?Regards

author: David_
author_rank: Contributor
timestamp: August 23, 2019, 02:56:36 am
content: I found a manufacturer which produces ultrasound transmitters based upon piezoelectric materials and apparently they cover the range of interest for me, I will contact them and ask them about my options for such a thing as this.

author: mark03
author_rank: Frequent Contributor
timestamp: August 23, 2019, 03:04:30 am
content: One thing to be aware of is that most transducers in that frequency range will be designed for operation in water, not air. The design of the transducer will be very different in each case, because the acoustic impedance of the medium is different. A transducer designed to operate in water (or be acoustically coupled to a solid surface) will emit virtually no sound in air; the energy will just bounce around inside.Also keep in mind that sound propagation in air becomes quite nonlinear at these high frequencies; as the wave propagates it rapidly loses energy to the harmonics that it generates. According to this handy reference,https://en.wikibooks.org/wiki/Engineering_Acoustics/Outdoor_Sound_Propagationat 200 kHz the attenuation is ~ 10 dB per meter.It might be difficult to find something off the shelf, because there aren't many commercial applications. IIRC some species of bats use that frequency range, I guess because the improved spatial resolution outweighs the shorter range. Bats are crazy loud, BTW; it might pay to study their vocal tract and mimic it! Out of curiosity, what did you have in mind?

author: David Hess
author_rank: Super Contributor
timestamp: August 23, 2019, 05:09:34 pm
content: I would first consider a piezoelectric transducer with a horn antenna for better efficiency. A high voltage amplifier will be required.