Very noisy signal from IMP34DT05

[frnt]

Hello,

I'm using the IMP34DT05 available with the STEVAL-MIC003V1 kit to record audio the nucleo-f401re. I'm using the PDM2PCM library to convert the PDM stream to PCM data. The audio is recorded at 8kHz.

I have tried reproducing 1kHz tone on the microphone. Unfortunately, after recording and listening to the .wav file on the computer it appears to be really noisy.

Do you know how can I solve this issue?

I have tried increasing the sampling frequency to 16kHz without success.

I upload the recorded .wav, by looking at the FFT the 1kHz peak is present. However, if you listen to the audio, playing it in audacity it is really bad. The signal-to-noise ratio seems to be really poor.

Any suggestion is welcome.

Thanks.

[Eleon BORLINI]

Hi @frnt​ ,

Are you acquiring noise from all the 4 mics?

If not, can you please check through visual inspection (magnitude 5x) from the inlet of the mic you are using the condition of the microphone MEMS?

-Eleon

[frnt · Accepted solution]

Hi @Eleon BORLINI​,

the problem has been solved in https://community.st.com/s/feed/0D53W00001YaPTFSA3

The issue was related to the bit order.

Thanks

[Eleon BORLINI]

Thank you for the update @frnt​ , so it was a problem related to the endianness of the PDM stream (changing the bit order in the PDM library from 1 to 0).

-Eleon