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how to get rid of ringing with IIR notch filters?

Started by Unknown December 22, 2003
Jerry Avins <jya@ieee.org> wrote:

>Matt Timmermans wrote: > >> >> There is a limit to how concentrated a signal can be in both time and >> frequency. In quantum mechanics, this implies Heisenberg's uncertainty >> principle, which is such a catchy name that a lot of people apply it to this >> time-frequency compactness limit in all circumstances. > >I'll try to come at this point another way. As R.B-J. pointed out, a >narrow notch can be made by subtracting a sharp peak from the original >signal ("short wire"). It doesn't matter how the notch is made; it >behaves like what it is. When an impulse excites a sharp peak, all the >energy comes out, but only at the peak's frequency. It follows that it >comes out over an extended period. Think about the impulse of a hammer >on a sharply tuned structure (say, a bell or a piano string) as you >think about what "ringing" means. > >Sharp resonances -- high Qs -- have steep sides. Low Q resonances have >broader bases for the same height. When the slope is low enough to >approximate critical damping, there's no ringing at all.
Thanks for the additional perspective. Robert www.gldsp.com ( modify address for return email ) www.numbersusa.com www.americanpatrol.com