I know how to design a lowpass, normalized IIR Bessel/Butter/Cheby I/Cheby II/elliptic filter, and I know how to transform that into a LP/HP/BP/BS filter at non-normalized frequencies, but I'm completely stumped on if it's possible to transform the prototype filter instead into a high shelf/low shelf/peak/notch filter. Is it?
No workarounds - I know I could simulate a peak/notch with traditional BP/BS using an arbitrary narrow band, and an equiripple FIR would give me a high shelf/low shelf design, but that's not what I'm asking...I'm curious if there are open source formulas to convert an arbitrary order (not just a single biquad) H(z) LP prototype IIR into a high/low shelf or peak/notch filter in the same manner as it can be transformed into the traditional LP/HP/BP/BS at arbitrary frequencies.
(I guess the alternative is to know the formula for a generic high shelf/low shelf/peak/notch filter of arbitrary order and frequency, which I also don't know, beyond 2nd order)
No workarounds - I know I could simulate a peak/notch with traditional BP/BS using an arbitrary narrow band, and an equiripple FIR would give me a high shelf/low shelf design, but that's not what I'm asking...I'm curious if there are open source formulas to convert an arbitrary order (not just a single biquad) H(z) LP prototype IIR into a high/low shelf or peak/notch filter in the same manner as it can be transformed into the traditional LP/HP/BP/BS at arbitrary frequencies.
(I guess the alternative is to know the formula for a generic high shelf/low shelf/peak/notch filter of arbitrary order and frequency, which I also don't know, beyond 2nd order)
Statistics: Posted by AnalogGuy1 — Fri Jan 12, 2024 7:37 pm — Replies 13 — Views 122