About Decimation

Algorithm development and general DSP issues

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dsPaul
Posts: 5
Joined: Thu Jul 17, 2014 12:12 pm

About Decimation

Post by dsPaul »

Hello,
i wrote a simple routine to perform decimation on samples, and i placed a 1 pole LPFs ahead to prevent aliasing but i'm not able to completly get rid of high freqencies ringing cause the slope of 1st order could be too low.
I could probably resolve this by analog conditioning at the input side, but i'd like to go digit.
Do you think that by higher order filtering is the way?
I ask this cause with 800Hz corner in the LPF, the guitar's treble were gone but i could still hear ringing at 16kHz (lower than without LPF, but still there). :roll:
Thank you
frank
Posts: 1244
Joined: Wed Oct 19, 2005 12:26 pm
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Post by frank »

A 1-pole is not enough, at 20db/decade you will only be about 26db down at 16K, you will want a higher order filter.
Frank Thomson
Experimental Noize
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