scipy.signal.iirdesign

scipy.signal.iirdesign(wp, ws, gpass, gstop, analog=0, ftype='ellip', output='ba')

Complete IIR digital and analog filter design.

Given passband and stopband frequencies and gains construct an analog or digital IIR filter of minimum order for a given basic type. Return the output in numerator, denominator (‘ba’) or pole-zero (‘zpk’) form.

Parameters :

wp, ws – Passband and stopband edge frequencies, normalized from 0 :

to 1 (1 corresponds to pi radians / sample). For example:

Lowpass: wp = 0.2, ws = 0.3 Highpass: wp = 0.3, ws = 0.2 Bandpass: wp = [0.2, 0.5], ws = [0.1, 0.6] Bandstop: wp = [0.1, 0.6], ws = [0.2, 0.5]

gpass – The maximum loss in the passband (dB). :

gstop – The minimum attenuation in the stopband (dB). :

analog – Non-zero to design an analog filter (in this case wp and :

ws are in radians / second).

ftype – The type of iir filter to design: :

elliptic : ‘ellip’ Butterworth : ‘butter’, Chebyshev I : ‘cheby1’, Chebyshev II: ‘cheby2’, Bessel : ‘bessel’

output – Type of output: numerator/denominator (‘ba’) or pole-zero (‘zpk’) :

Returns :

b,a – Numerator and denominator of the iir filter. :

z,p,k – Zeros, poles, and gain of the iir filter.