To experts in this forum,
I am trying to measure sound at high frequency between 20kHz and 80kHz.
I am currently using Arduino Nano BLE.
Is this feasible? And if so, what sound sensor you recommend ?
Perhaps a piezo disk and BJT but not sure how precise you can measure frequency.
- Is this frequency travelling in the air ?
No, it is travelling though soil
I believe the maximum sampling rate is around 50kHz, so just barely usable for 20kHz but not higher. So not feasible.
To measure the frequency, you will need a microphone capable of responding to > 80 kHz, and sample the microphone output at > 160 kHz to meet the Nyquist criterion.
The sample frequency must be at least twice as high as any frequency component present in the input signal.
There are special ultrasonic microphones but you'll have to search. You'll also need a preamp that works above the audio range, and probably a high-pass filter.
Do you need to measure frequency? If you just need to to measure the amplitude after filtering you can use a peak detector which puts-out varying DC that any Arduino can measure.
There are USB Audio Interfaces with sample rates of 192kHz (or higher). They work with a computer and they use "pro" XLR microphone connections. But they are designed for audio so a high sample rate doesn't guarantee they go ultrasonic.
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