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Topic: ultrasound analogoc sensor (Read 308 times) previous topic - next topic

arkeis

Hello,
I'm looking for an ultrasound sensor that would return an analogic signal depending on the intensity of the said ultrasound; I don't want to measur a distance, but an the intensity of the echo (I've already got a transmitter).
I don't need anything precise, or a huge range, and I'd like it to be centered around 40kHz. Any information would be precious. I hope this is not considered a repost, and that my issue is clear.
Thanks in advance !

Paul_KD7HB

Hello,
I'm looking for an ultrasound sensor that would return an analogic signal depending on the intensity of the said ultrasound; I don't want to measur a distance, but an the intensity of the echo (I've already got a transmitter).
I don't need anything precise, or a huge range, and I'd like it to be centered around 40kHz. Any information would be precious. I hope this is not considered a repost, and that my issue is clear.
Thanks in advance !
Since you already have the transmitter, you already have the receiver. In all the hobby type sensors, the transmitter is switched to receive after sending some number of pulses.

If you want to receive-only, then you are looking for a microphone that can receive your 40kHz signal. Then that signal will need to be electronically processed to give you a variable voltage based on the level of the received audio.

Now, there comes the problem of finding the echo of the pulse you transmitted from all the other noise your microphone will be receiving. But your program should be able to limit the time frame that is being examined.

Paul

arkeis

Hi, thank you for your answer !
The thing is my transmitter can only return a duration, that can be converted to a distance. There is no analogic output, like any transmitter I think. And I don't have the DIY skills or suff to hack it like I saw on this forum. So, as you said, I need an adapted microphone.
The issue is I don't really know wher to look, and I don't seem to can find any precise specifications on the sites I visited. Any indication would be welcome !

jremington

I doubt such a sensor exists, at least commercially.

Perhaps if you explained what you actually want to do, we could help.

Paul_KD7HB

A Google search for "microphone ultrasonic" returned this.

Might give some direction for your research.

Paul

arkeis

Perhaps if you explained what you actually want to do, we could help.
You're right, I should explain;
The objective is to model the use of utrasound in the gestion of fishing resources. The idea is to 'count' the fish beneath the sonar, by detecting their acoustic impedance, and thus their number (density) and nature.
This guy: https://archimer.ifremer.fr/doc/00497/60865/ explains it much better than me in his intro. It' in french but you can still read the abstract.
To do short, I need to send ultrasounds in a water batch with floating objects in it, and analyse the echoes.
I hope that's clear enough ?

wvmarle

Air based ultrasound does not work underwater (and not just for the waterproofing part).

Look into fish finders, they do exactly that, albeit listening (like normal sonar) how long it takes for the signal to come back. That are underwater ultrasound transducers, typically working at much higher frequencies than the 40 kHz which is commonly used in air.

Whether the loudness of the signal has any bearing I really don't know.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

jremington

#7
Feb 18, 2020, 07:33 pm Last Edit: Feb 18, 2020, 07:34 pm by jremington
For certain, the author of the study you linked used very expensive, professional underwater acoustic depth sounding equipment. If the thesis is in your native language, the equipment and its usage should be clearly identified and described.

This is not a project for amateurs.

Paul_KD7HB

I see in your link the frequent use of the term: "broadband acoustic". That tells me he was using "chirping" or frequency shift during the pulse and tying that shift to the receiver.

Same is used in radar to identify the type and size of the target aircraft.

Paul

arkeis

For certain, the author of the study you linked used very expensive, professional underwater acoustic depth sounding equipment. If the thesis is in your native language, the equipment and its usage should be clearly identified and described.

This is not a project for amateurs.
Indeed, he uses professional equipment, with a range of hundreds / thousands of meters. I'm well aware of that. But I just need to reproduce the experiences in a much smaller scale. Like an aquarium. So I don't think it is irrealistic. Is it ?

wvmarle

Reproducing the equipment is probably not realistic as you don't seem to know much about underwater acoustics and sonar. This is obviously a very advanced project in that field, so unless you're an expert in that field (in which case you wouldn't be asking here) you almost certainly won't be able to pull that off.

I for one know I don't stand a chance to produce such a project, so if I needed it I'd be asking my employer for a budget big enough to simply buy the equipment, or hire someone to build it for me. That way you could at least reproduce the results, or use the technology for measurements on fish stocks or so.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

arkeis

I see in your link the frequent use of the term: "broadband acoustic". That tells me he was using "chirping" or frequency shift during the pulse and tying that shift to the receiver.

Same is used in radar to identify the type and size of the target aircraft.

Paul
Indeed, he operates with 18, 38, 70, 120, 200 and 333kHz.But I find three different transmitters that would be good enough.

Paul_KD7HB

Indeed, he operates with 18, 38, 70, 120, 200 and 333kHz.But I find three different transmitters that would be good enough.
Then you would need three different receivers and be able to sync the transmitters and receivers so they saw the same target at almost the same time.

Paul

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