Re: IIR notch filter

On Jun 26, 11:22 pm, Jerry Avins <j...@[EMAIL PROTECTED]
> wrote:
> Tim Wescott wrote:
>
> > I just make a plain ol' notch.  For a transfer function given a notch
> > frequency and bandwidth, look here:http://www.dsprelated.com/
> > showmessage/81610/1.php.
>
> > A good book on DSP should show you how to calculate your numerical
> > effects.
>
> Tim, you need to figure out how to stop your newsreader from breaking
> URLs.http://www.dsprelated.com/showmessage/81610/1.php.

i always just put it on a separate line.

and, to drive the point more deeply home.  for a 2nd-order notch,
there is no Butterworth vs. Tchebyshev.  it's a mapping from a 1st-
order LPF prototype with the substitution

     s  <---  1/(s^2 + w0^2)

with a 4th-order notch (mapped as above from a 2nd-order LPF) then
there's a difference.  dunno why anyone would want it.

r b-j