anti-aliasing with a FIR filter

[benejoseph]

The existing antialiasing filters were both removing high frequency signals of interest (i.e. filtering in-band) and simultaneously not removing enough of the aliased signals. The way to fix this was with a very sharp FIR filter.

• Replaced 2nd order butterworth lpf @8khz with 128 tap FIR filter in the codec (which had to be copy and pasted in one coefficient at at time, aggggghghhh)
• Removed "averaging filter" from pcm_handler.c as this will affect in-band signal
• Existing neural net goes from passing 16/30 to 26/30 in sound box test

[plasticchris]

Yeah

On Mon, Dec 12, 2016, 5:02 PM Ben notifications@github.com wrote:

is that a +1?

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