robert bristow-johnson wrote:
> On Oct 9, 5:21=A0pm, "sauwen" <sauwen...@[EMAIL PROTECTED]
> wrote:
>
> > Hi all. =A0Does anyone know how to change the width of a feedback comb
> > filter's teeth? From the general idea on wikipedia, it seems like it
is
> > only possible to change the delays and the gain.
>
> when you have a feedback comb filter (or even a feed-forward comb
> filter), try to imagine replacing the delay element, z^-N, with a
> quantitatively different delay element, z^-1. =A0then with that
> feedback, you have a simple LPF where, depending on the feedback gain,
> you can get an idea of how wide this single tooth is. =A0now replace
> z^-1 with z^-N and you will see that your tooth is scrunched by a
> factor of 1/N and there are N of these teeth from -Nyquist to just
> under +Nyquist.
>
> does that help you figger it out?
But what to do if you have a comp filter where you are interested in N
notches and now want to sharpen those notches without increasing their
number? FIR filter sharpening to the rescue!
Matthew's original DSP Guru article is now published (well done
Matthew, whereever you are!) but still downloadable:
http://www.dsprelated.com/showabstract/62.php
Regards,
Andor
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