PDM_Filter output of its 1st 2 PCM-converted data seems to be erroneous

siorpaes / pdm_playground

Collection of miscellaneous tools for PDM signals generation, acquisition and decoding

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PDM_Filter output of its 1st 2 PCM-converted data seems to be erroneous #1

Closed VictorTagayun closed 3 years ago

VictorTagayun commented 3 years ago

Not an issue but an inquiry.

Do you encounter the 1st 2 PCM-converted data seems to be erroneous?

I posted in ST Community in this link https://community.st.com/s/question/0D53W000019CZzmSAG/pdmfilter-erroneous-1st-2-pcmconverted-data

I asked here because I used you PDM tones.

siorpaes commented 3 years ago

Hello, I guess the problem is related to inherent FIR filter transient response. You need to wait at least N-1 samples, where N is the length of the filter, to have correct data. See, for example,

https://www.dsprelated.com/freebooks/filters/Transient_Response_Steady_State.html