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Altera_Forum's avatar
Altera_Forum
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16 years ago

Question about FIR filter outputs

Hi, I designed FIR filter and I try to undestand why the number of output samples is different from the input? It lacks 2-3 samples. Thank you for your help.
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
16 years ago

How do you do the counting? hopefully not by fingers...

Every filter output needs initial time to settle.

the internal delay line(same as number of taps) have to be filled up first. The output will only be correct after this delay line is full.

just in case, groupdelay of FIR is order/2 and is a different concept.