hi! All, i would like some info on implementing cascade form IIR filters...does matlab support it???...as far as i can understand butter,cheby1,cheby2,bessel,ellip generate coefficients in the direct form...how do i implement the cascade form... TIA bngguy
Cascade Form IIR Filters
Started by ●April 19, 2004
Reply by ●April 19, 20042004-04-19
bngguy wrote:> hi! All, > i would like some info on implementing cascade form IIR > filters...does matlab support it???...as far as i can understand > butter,cheby1,cheby2,bessel,ellip generate coefficients in the direct > form...how do i implement the cascade form... > > TIA > bngguyI don't know if Matlab supports it, but cascading filters is relatively easy. Here's the process I use: 1. Factor your numerator and denominator polynomials 2. Combine all your complex pairs into 2nd-order polynomials 3. Match zeros up to their closest denominators (I don't know the "best" way to do this, use your intuition). 4. Build as many 1st- and 2nd- order polynomials you need 5. Check your gains from the input to the states, to verify that nothing will overflow. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com
Reply by ●April 19, 20042004-04-19
Matlab generally refers to this as second order sections or SOS for short. There are several functions in the SP toolbox that convert to/from the SOS form including TF2SOS. "Tim Wescott" <tim@wescottnospamdesign.com> wrote in message news:1088dnid0eobb0b@corp.supernews.com...> bngguy wrote: > > hi! All, > > i would like some info on implementing cascade form IIR > > filters...does matlab support it???...as far as i can understand > > butter,cheby1,cheby2,bessel,ellip generate coefficients in the direct > > form...how do i implement the cascade form... > > > > TIA > > bngguy > > I don't know if Matlab supports it, but cascading filters is relatively > easy. Here's the process I use: > > 1. Factor your numerator and denominator polynomials > 2. Combine all your complex pairs into 2nd-order polynomials > 3. Match zeros up to their closest denominators (I don't know the > "best" way to do this, use your intuition). > 4. Build as many 1st- and 2nd- order polynomials you need > 5. Check your gains from the input to the states, to verify > that nothing will overflow.
Reply by ●April 19, 20042004-04-19
bngguy wrote:> hi! All, > i would like some info on implementing cascade form IIR > filters...does matlab support it???...as far as i can understand > butter,cheby1,cheby2,bessel,ellip generate coefficients in the direct > form...how do i implement the cascade form... > > TIA > bngguy"Cascade" refers to a chain of second-order sections. Sure, Matlab does that. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●April 20, 20042004-04-20
Hello, Yes, Mathlab supports it. Also, ONEoverT will implement cascade form IIR filter very easily as well. Bob Carter loosepraje@yahoo.com (bngguy) wrote in message news:<519f37cf.0404191215.6760b325@posting.google.com>...> hi! All, > i would like some info on implementing cascade form IIR > filters...does matlab support it???...as far as i can understand > butter,cheby1,cheby2,bessel,ellip generate coefficients in the direct > form...how do i implement the cascade form... > > TIA > bngguy