| Electronics > Projects, Designs, and Technical Stuff |
| What to know ehen choosing/searching a Ultrasonic microphone |
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| Detzi:
Good Day, i am in search for a pcb mounted ultrasonic microphone with an analog out and a bandwidth up to 100kHz, so i had a look around. ST manufactures not really something usefull, the best match given by their support fails any of my requirements but has an analog out... Knowles seems to offer quite a lot MEMS Microphones where one of them the SPU0410LR5H-QB seems to tick almost all boxes. It has at least specified a free field response up to 80kHz more than most others. TDK also has a good match, the ICS-41352 sadly it has a PDM and no analog out and again it ranges only up to 80kHz. When searching for alternatives it feels quite time consuming because there are no filters like "frequency range" or "ultrasonic" on manufacturers sites. Mouser and digi-key do have such filters but only Mouser lists a device (a single one) after selecting just the frequency range. Has one of you guys a good way to search for these things, or can you even recommend a specific one? Has someone experience with these MEMS-Devices and can give me some tips about their system integration? Are there advantages/disadvantages compared to other technologies, like electret microphones? Thanks in advance! |
| coppercone2:
I am suspicious that you can take a typical tiny microphone, like one of those pinhole types you have in a phone thats SMD mount, and then mill out the hole to greatly increase frequency response. I noticed the ultrasonics in the same form factor have like, 10x the area at the inlet (big square) and its usually meshed, vs a tiny hole for regular mics. I think the brand I have is MEMS |
| SiliconWizard:
The mounting will probably be critical to get reasonable freq response at those high frequencies. I'd guess a top port would be easier to deal with than a bottom port, but what about the enclosure it's going to be in? I remember we already had a thread about something similar (would have to find it back). There were very few MEMS microphones for frequencies that high. PDM is not that hard to deal with, do not let that deter you. You can basically convert that to analog with a low-pass filter of reasonable order. (1-st order will probably not be enough.) Advantages of MEMS: usually more rugged, much smaller. Obviously direct PCB mounting. |
| coppercone2:
https://www.digikey.com/en/articles/techzone/2011/may/ultrasonic-mems-sensor-spm0404ud5 |
| SiliconWizard:
--- Quote from: coppercone2 on August 06, 2019, 12:27:52 am ---https://www.digikey.com/en/articles/techzone/2011/may/ultrasonic-mems-sensor-spm0404ud5 --- End quote --- See the typical frequency response above ~15kHz though - it would require some serious calibration (unless the OP doesn't care much about amplitude). Hope the OP is ready to do that. |
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