[OT] How to produce IIR filter coefficients from a set of points describing the frequency response
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[OT] How to produce IIR filter coefficients from a set of points describing the frequency response
by Andres Cabrera
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Hi all,
The subject asks the question... What I want to know is if there's an easy way using something like pylab and numpy to produce a set of coefficients for an IIR filter from a given frequency response. I've read on the internet that matlab has the invresz function which does this, but is there an easy way with free software? Cheers Andrés ------------------------------------------------------------------------------ Crystal Reports - New Free Runtime and 30 Day Trial Check out the new simplified licensing option that enables unlimited royalty-free distribution of the report engine for externally facing server and web deployment. http://p.sf.net/sfu/businessobjects _______________________________________________ Csound-devel mailing list Csound-devel@... https://lists.sourceforge.net/lists/listinfo/csound-devel |
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Re: [OT] How to produce IIR filter coefficients from a set ofpoints describing the frequency response
by Victor Lazzarini
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scipy has a signal processing module:
NAME scipy.signal FILE c:\python25\lib\site-packages\scipy\signal\__init__.py DESCRIPTION Signal Processing Tools ======================= Convolution: convolve -- N-dimensional convolution. correlate -- N-dimensional correlation. fftconvolve -- N-dimensional convolution using the FFT. convolve2d -- 2-dimensional convolution (more options). correlate2d -- 2-dimensional correlation (more options). sepfir2d -- Convolve with a 2-D separable FIR filter. B-splines: bspline -- B-spline basis function of order n. gauss_spline -- Gaussian approximation to the B-spline basis function. cspline1d -- Coefficients for 1-D cubic (3rd order) B-spline. qspline1d -- Coefficients for 1-D quadratic (2nd order) B-spline. cspline2d -- Coefficients for 2-D cubic (3rd order) B-spline. qspline2d -- Coefficients for 2-D quadratic (2nd order) B-spline. spline_filter -- Smoothing spline (cubic) filtering of a rank-2 array. Filtering: order_filter -- N-dimensional order filter. medfilt -- N-dimensional median filter. medfilt2 -- 2-dimensional median filter (faster). wiener -- N-dimensional wiener filter. symiirorder1 -- 2nd-order IIR filter (cascade of first-order systems). symiirorder2 -- 4th-order IIR filter (cascade of second-order systems) . lfilter -- 1-dimensional FIR and IIR digital linear filtering. deconvolve -- 1-d deconvolution using lfilter. hilbert -- Compute the analytic signal of a 1-d signal. get_window -- Create FIR window. detrend -- Remove linear and/or constant trends from data. resample -- Resample using Fourier method. Filter design: remez -- Optimal FIR filter design. firwin -- Windowed FIR filter design. iirdesign -- IIR filter design given bands and gains. iirfilter -- IIR filter design given order and critical frequencies. freqs -- Analog filter frequency response. freqz -- Digital filter frequency response. unique_roots -- Unique roots and their multiplicities. residue -- Partial fraction expansion of b(s) / a(s). residuez -- Partial fraction expansion of b(z) / a(z). invres -- Inverse partial fraction expansion. Matlab-style IIR filter design: butter (buttord) -- Butterworth cheby1 (cheb1ord) -- Chebyshev Type I cheby2 (cheb2ord) -- Chebyshev Type II ellip (ellipord) -- Elliptic (Cauer) bessel -- Bessel (no order selection available -- try butterord) Linear Systems: lti -- linear time invariant system object. lsim -- continuous-time simulation of output to linear system. impulse -- impulse response of linear, time-invariant (LTI) system. step -- step response of continous-time LTI system. LTI Reresentations: tf2zpk -- transfer function to zero-pole-gain. zpk2tf -- zero-pole-gain to transfer function. tf2ss -- transfer function to state-space. ss2tf -- state-pace to transfer function. zpk2ss -- zero-pole-gain to state-space. ss2zpk -- state-space to pole-zero-gain. Waveforms: sawtooth -- Periodic sawtooth square -- Square wave gausspulse -- Gaussian modulated sinusoid chirp -- Frequency swept cosine signal Window functions: boxcar -- Boxcar window triang -- Triangular window parzen -- Parzen window bohman -- Bohman window blackman -- Blackman window blackmanharris -- Minimum 4-term Blackman-Harris window nuttall -- Nuttall's minimum 4-term Blackman-Harris window flattop -- Flat top window bartlett -- Bartlett window hann -- Hann window barthann -- Bartlett-Hann window hamming -- Hamming window kaiser -- Kaiser window gaussian -- Gaussian window general_gaussian -- Generalized Gaussian window slepian -- Slepian window Wavelets: daub -- return low-pass filter for daubechies wavelets qmf -- return quadrature mirror filter from low-pass cascade -- compute scaling function and wavelet from coefficients Victor ----- Original Message ----- From: "Andres Cabrera" <mantaraya36@...> To: "Developer discussions" <csound-devel@...> Sent: Friday, May 15, 2009 12:54 PM Subject: [Cs-dev] [OT] How to produce IIR filter coefficients from a set ofpoints describing the frequency response Hi all, The subject asks the question... What I want to know is if there's an easy way using something like pylab and numpy to produce a set of coefficients for an IIR filter from a given frequency response. I've read on the internet that matlab has the invresz function which does this, but is there an easy way with free software? Cheers Andrés ------------------------------------------------------------------------------ Crystal Reports - New Free Runtime and 30 Day Trial Check out the new simplified licensing option that enables unlimited royalty-free distribution of the report engine for externally facing server and web deployment. http://p.sf.net/sfu/businessobjects _______________________________________________ Csound-devel mailing list Csound-devel@... https://lists.sourceforge.net/lists/listinfo/csound-devel ------------------------------------------------------------------------------ Crystal Reports - New Free Runtime and 30 Day Trial Check out the new simplified licensing option that enables unlimited royalty-free distribution of the report engine for externally facing server and web deployment. http://p.sf.net/sfu/businessobjects _______________________________________________ Csound-devel mailing list Csound-devel@... https://lists.sourceforge.net/lists/listinfo/csound-devel |
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Re: [OT] How to produce IIR filter coefficients from a set ofpoints describing the frequency response
by Andres Cabrera
::
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Thanks for the ideas. I've been playing with sage all afternoon and
it's great. I'd heard about it, but had not dared install it... But on the topic of iir filter coeficients, I haven't been able to find how... with scipy.signal, there are two functions for creating filters: iirfiter and iirdesign, but they are not designed for arbitrary filter responses, since they model classic bp, hp, lp and br filters. I've found remez, but it's for fir filters. Am I missing something? Cheers, Andrés On Fri, May 15, 2009 at 5:14 PM, Jim Bates <jabates@...> wrote: > From: victor <Victor.Lazzarini@...> > This absolutely impressive, but scary! > > True. Running on OSX 10.4, 1.67 Ghz and 2 GB RAM, Sage will compute pi > to 100,000 places in just under 9 seconds. It uses Cython which is a C > extension > for Python. It is quite fast. ( http://cython.org/ ) > All the Best, > Jim > ------------------------------------------------------------------------------ > Crystal Reports - New Free Runtime and 30 Day Trial > Check out the new simplified licensing option that enables > unlimited royalty-free distribution of the report engine > for externally facing server and web deployment. > http://p.sf.net/sfu/businessobjects > _______________________________________________ > Csound-devel mailing list > Csound-devel@... > https://lists.sourceforge.net/lists/listinfo/csound-devel > > -- Andrés ------------------------------------------------------------------------------ Crystal Reports - New Free Runtime and 30 Day Trial Check out the new simplified licensing option that enables unlimited royalty-free distribution of the report engine for externally facing server and web deployment. http://p.sf.net/sfu/businessobjects _______________________________________________ Csound-devel mailing list Csound-devel@... https://lists.sourceforge.net/lists/listinfo/csound-devel |
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Re: [OT] How to produce IIR filter coefficients from a set ofpoints describing the frequency response
by Andres Cabrera
::
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The matlab function I'm looking for is acually called invfreqz, not
invresz which is there in scipy. Cheers, Andrés On Fri, May 15, 2009 at 9:08 PM, Andres Cabrera <mantaraya36@...> wrote: > Thanks for the ideas. I've been playing with sage all afternoon and > it's great. I'd heard about it, but had not dared install it... > But on the topic of iir filter coeficients, I haven't been able to > find how... with scipy.signal, there are two functions for creating > filters: iirfiter and iirdesign, but they are not designed for > arbitrary filter responses, since they model classic bp, hp, lp and br > filters. I've found remez, but it's for fir filters. > Am I missing something? > > Cheers, > Andrés > > > On Fri, May 15, 2009 at 5:14 PM, Jim Bates <jabates@...> wrote: >> From: victor <Victor.Lazzarini@...> >> This absolutely impressive, but scary! >> >> True. Running on OSX 10.4, 1.67 Ghz and 2 GB RAM, Sage will compute pi >> to 100,000 places in just under 9 seconds. It uses Cython which is a C >> extension >> for Python. It is quite fast. ( http://cython.org/ ) >> All the Best, >> Jim >> ------------------------------------------------------------------------------ >> Crystal Reports - New Free Runtime and 30 Day Trial >> Check out the new simplified licensing option that enables >> unlimited royalty-free distribution of the report engine >> for externally facing server and web deployment. >> http://p.sf.net/sfu/businessobjects >> _______________________________________________ >> Csound-devel mailing list >> Csound-devel@... >> https://lists.sourceforge.net/lists/listinfo/csound-devel >> >> > > > > -- > > > Andrés > -- Andrés ------------------------------------------------------------------------------ Crystal Reports - New Free Runtime and 30 Day Trial Check out the new simplified licensing option that enables unlimited royalty-free distribution of the report engine for externally facing server and web deployment. http://p.sf.net/sfu/businessobjects _______________________________________________ Csound-devel mailing list Csound-devel@... https://lists.sourceforge.net/lists/listinfo/csound-devel |
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Re: [OT] How to produce IIR filter coefficients from a setofpoints describing the frequency response
by Victor Lazzarini
::
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Octave seems to have it:
https://prof.hti.bfh.ch/sha1/Octave/index/f/invfreqz.html ----- Original Message ----- From: "Andres Cabrera" <mantaraya36@...> To: "Developer discussions" <csound-devel@...> Sent: Saturday, May 16, 2009 3:12 AM Subject: Re: [Cs-dev] [OT] How to produce IIR filter coefficients from a setofpoints describing the frequency response The matlab function I'm looking for is acually called invfreqz, not invresz which is there in scipy. Cheers, Andrés On Fri, May 15, 2009 at 9:08 PM, Andres Cabrera <mantaraya36@...> wrote: > Thanks for the ideas. I've been playing with sage all afternoon and > it's great. I'd heard about it, but had not dared install it... > But on the topic of iir filter coeficients, I haven't been able to > find how... with scipy.signal, there are two functions for creating > filters: iirfiter and iirdesign, but they are not designed for > arbitrary filter responses, since they model classic bp, hp, lp and br > filters. I've found remez, but it's for fir filters. > Am I missing something? > > Cheers, > Andrés > > > On Fri, May 15, 2009 at 5:14 PM, Jim Bates <jabates@...> wrote: >> From: victor <Victor.Lazzarini@...> >> This absolutely impressive, but scary! >> >> True. Running on OSX 10.4, 1.67 Ghz and 2 GB RAM, Sage will compute pi >> to 100,000 places in just under 9 seconds. It uses Cython which is a C >> extension >> for Python. It is quite fast. ( http://cython.org/ ) >> All the Best, >> Jim >> ------------------------------------------------------------------------------ >> Crystal Reports - New Free Runtime and 30 Day Trial >> Check out the new simplified licensing option that enables >> unlimited royalty-free distribution of the report engine >> for externally facing server and web deployment. >> http://p.sf.net/sfu/businessobjects >> _______________________________________________ >> Csound-devel mailing list >> Csound-devel@... >> https://lists.sourceforge.net/lists/listinfo/csound-devel >> >> > > > > -- > > > Andrés > -- Andrés ------------------------------------------------------------------------------ Crystal Reports - New Free Runtime and 30 Day Trial Check out the new simplified licensing option that enables unlimited royalty-free distribution of the report engine for externally facing server and web deployment. http://p.sf.net/sfu/businessobjects _______________________________________________ Csound-devel mailing list Csound-devel@... https://lists.sourceforge.net/lists/listinfo/csound-devel ------------------------------------------------------------------------------ Crystal Reports - New Free Runtime and 30 Day Trial Check out the new simplified licensing option that enables unlimited royalty-free distribution of the report engine for externally facing server and web deployment. http://p.sf.net/sfu/businessobjects _______________________________________________ Csound-devel mailing list Csound-devel@... https://lists.sourceforge.net/lists/listinfo/csound-devel |
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Re: [OT] How to produce IIR filter coefficients from a setofpoints describing the frequency response
by Andres Cabrera
::
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Yes, that's what I was looking for. The great thing is that I can use
this from sage. Thanks for the ideas. Cheers, Andrés On Sat, May 16, 2009 at 1:20 AM, victor <Victor.Lazzarini@...> wrote: > Octave seems to have it: > https://prof.hti.bfh.ch/sha1/Octave/index/f/invfreqz.html > ----- Original Message ----- > From: "Andres Cabrera" <mantaraya36@...> > To: "Developer discussions" <csound-devel@...> > Sent: Saturday, May 16, 2009 3:12 AM > Subject: Re: [Cs-dev] [OT] How to produce IIR filter coefficients from a > setofpoints describing the frequency response > > > The matlab function I'm looking for is acually called invfreqz, not > invresz which is there in scipy. > > Cheers, > Andrés > > On Fri, May 15, 2009 at 9:08 PM, Andres Cabrera <mantaraya36@...> > wrote: >> Thanks for the ideas. I've been playing with sage all afternoon and >> it's great. I'd heard about it, but had not dared install it... >> But on the topic of iir filter coeficients, I haven't been able to >> find how... with scipy.signal, there are two functions for creating >> filters: iirfiter and iirdesign, but they are not designed for >> arbitrary filter responses, since they model classic bp, hp, lp and br >> filters. I've found remez, but it's for fir filters. >> Am I missing something? >> >> Cheers, >> Andrés >> >> >> On Fri, May 15, 2009 at 5:14 PM, Jim Bates <jabates@...> wrote: >>> From: victor <Victor.Lazzarini@...> >>> This absolutely impressive, but scary! >>> >>> True. Running on OSX 10.4, 1.67 Ghz and 2 GB RAM, Sage will compute pi >>> to 100,000 places in just under 9 seconds. It uses Cython which is a C >>> extension >>> for Python. It is quite fast. ( http://cython.org/ ) >>> All the Best, >>> Jim >>> ------------------------------------------------------------------------------ >>> Crystal Reports - New Free Runtime and 30 Day Trial >>> Check out the new simplified licensing option that enables >>> unlimited royalty-free distribution of the report engine >>> for externally facing server and web deployment. >>> http://p.sf.net/sfu/businessobjects >>> _______________________________________________ >>> Csound-devel mailing list >>> Csound-devel@... >>> https://lists.sourceforge.net/lists/listinfo/csound-devel >>> >>> >> >> >> >> -- >> >> >> Andrés >> > > > > -- > > > Andrés > > ------------------------------------------------------------------------------ > Crystal Reports - New Free Runtime and 30 Day Trial > Check out the new simplified licensing option that enables > unlimited royalty-free distribution of the report engine > for externally facing server and web deployment. > http://p.sf.net/sfu/businessobjects > _______________________________________________ > Csound-devel mailing list > Csound-devel@... > https://lists.sourceforge.net/lists/listinfo/csound-devel > > > ------------------------------------------------------------------------------ > Crystal Reports - New Free Runtime and 30 Day Trial > Check out the new simplified licensing option that enables > unlimited royalty-free distribution of the report engine > for externally facing server and web deployment. > http://p.sf.net/sfu/businessobjects > _______________________________________________ > Csound-devel mailing list > Csound-devel@... > https://lists.sourceforge.net/lists/listinfo/csound-devel > -- Andrés ------------------------------------------------------------------------------ Crystal Reports - New Free Runtime and 30 Day Trial Check out the new simplified licensing option that enables unlimited royalty-free distribution of the report engine for externally facing server and web deployment. http://p.sf.net/sfu/businessobjects _______________________________________________ Csound-devel mailing list Csound-devel@... https://lists.sourceforge.net/lists/listinfo/csound-devel |
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