How to use inexpensive transducers for ultrasonic measurement 

Thanks!

Well it depends on how much you value your time and if you are willing to "cheat" a little. First of all, you can do that without spending any money and simply looking at the pcb of the device: just google the ics and try to understand what they do(your journey may be concluded right on this step if you spend long enough on it). Another thing you can do is to buy a simple 10$ osciloscope or frequency measurement device, with the same osciloscope you can actually detect the ultrasound waves in the air if you buy an ultrasound receiver, so if you are unwilling to disassemble the device you can try that(but do keep in mind that received signal will be quite weak, and that ultrasound is kinda a finiky thing in itself, so you might find it troubling to do that). You can also try to forego the osciloscope entirely and stick with your plain old sound card which you probably already have(but do keep in mind that they usually have some capacitors on the input and output to "smooth out" high frequncy "noise", aka the thing we are trying to capture and that they are usually not tolerant towards high voltages), or you can with microcontroller or you can buy an arduino ultrasonic module that can be interfeced to your pc with something like a usb to ttl(or if you have a physical com port on it you can go with it). All in all i would say that it is much easier and cheaper to just find a few stray cats and test it on them directly rather than going through all that hassle.

+VortexTwin: You are correct I should have said "pressure wave".

i stopped at that **"electromagnetic"** word and started looking for your comment

@@mattminasi4856 Matt are you able to use this device to determine the transmitted power? This would solve a major problem my company has with a device they manufacture

That depends on the transducer and how much amplification required. The TDC parts are designed to operate in 1-5Mhz range. Good news for you is that's low frequency so it would be pretty easy to just do those measurements with good oscilloscope. A Rigol off Amazon will also provide a poor man's FFT of the signal. Good luck!

Not sure I understand the question but with piezos the physical dimensions determine is primary resonance frequency. So in general they are designed to work for a specific range. the diameter (size) has more to do with acoustic transmission power. For instance 2 transducers can have the same resonant frequency but one that 2x the diameter has the capacity to create a larger acoustic wave AND it will detect a smaller acoustic signal for the same excitation voltage.

not really. glass isn't a uniform substrate, it's a composite. your resin "rings" at one speed, your actual glass at another, any kevlar at another, carbon fiber at another, then your core at yet one more (assuming single material core), and any foam layers dampening. now add gelcoat, lol. it's sketchy on a metal hull unless you REALLY engineer the mounting point for accuracy. now, that isnt to say "it's impossible!!", because you COULD get it to work. but, the energy you would have to put behind each pulse would be huge in comparison to a wet transducer like the fish finders use. to measure level in glass tanks, folks usually mount a transducer at the top to measure level by echo off the actual surface through air, avoiding the tank composite. a single material (glass, stainless, plastic) plate can be used in a top mount to avoid corrosive fumes. but tanks dont bounce in the briny deep, especially their "dry" side, lol. so yes, it can be done, but the economy of scale makes it impractical. better perhaps to think more along the lines of a pod to hang off the gunwale, or transom. then you can mount to a uniform material plate, back dampen and waterproof as a single operation, and avoid the headaches, lol

that''s a tricky one because "clicks" at like a CHIRP in DSP terminology. In that they have a very frequency components. I'd suggest a wide band microphone vs a piezo. The best way think about a piezo is like a "bell" that rings at a primary harmonic. It will resonate at multiples of that primary but not well.

Did you get the answer? I have the same question

Absolutely! If you check out the app note I did back when I used to work for TI I showed how you can glue transducers on a metal tank and measure liquid volume. The gotcha is tank wall thickness! The thicker the wall the more (acoustic) power required on the transmit pulse. Also I recall wine vats have a cooling jacket (not sure about the bottom) but if they do that will make it hard. Depending on your tank it may be easier to measure level from the top via "the air".