| 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"
To: "Developer discussions"
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
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