PGA SD ADC and FFT resonant frequency of the measured signal by piezo sensor

Thread Starter


Joined Jun 28, 2020
I was inspired by the Non-Intrusive Tank-Filling Sensor Based on Sound Resonance article.

In my case, I would like to measure whether I will have to empty a full plastic septic tank of about 5 m3 volume by tapping a solenoid on the outside of the septic tank placed in the ground, measuring the response using a piezoelectric sensor and calculating the resonance frequency of the septic tank filling volume using an FFT.

I will then send the measured value using the ATSAMR34 to the LoRaWAN network.

I have already ordered the solenoid and the piezo sensor (I can use just the piezo element if necessary).

What chip would you recommend for PGA and Sigma Delta ADC? Is there any chip on the market that would directly process the captured data using FFT and the output would be the frequency of the given volume of the tank that I would just pass to ATSAMR34? I don't need to continuously measure the actual filling volume of the tank, I only want to reliably identify its maximum filling.