Suffering noise from MCC 128 and MCC 172

[skycraper3]

Hello, our team using MCC128 and MCC172 DAQs but suffering buzzing noise when use 3.3V MEMS microphones.

This problem occurred few months ago, but we didn't got any clues on this problem.

3.3V microphones using VCC and GND from raspberry pi 3 itself, audio output is directly connected in High channels like CH0+ or CH0H.

Microphones are tested properly and all works fine but when we starts recording on MCC128 or MCC172, we got buzzing sound during normal signals.

We tried few MEMS micrphones and also tried RaspberryPi 4 but results are not so different.

Can we get any solution or advice on this problem?

Attached images are noise plot and spectrogram, we using 4 channels, 2048 Hz sampling rates. Y axis on plot is Voltage.

 

Edited May 9 by skycraper3

[JRys]

It would be easier to comment if I knew more details. For example, is the 128 set to the differential mode or single-ended? Are there other sensors connected and if so what are they? If you disconnect the other sensors, does the buzz go away? Can you attach the microphone's data sheet?

[JRys]

The microphone looks good, and I don't see anything obvious with the setup; however, a noise burst every 10 seconds seems manufactured. Could you turn off nearby equipment to see if it changes anything?

 

[JRys]

Hello,

I'm surprised that the noise was present only when there was no wifi and that disabling the RPI wifi module solved the problem. 

Thanks,
John