bilinear(b, a, fs=1.0)
Transform a set of poles and zeros from the analog s-plane to the digital z-plane using Tustin's method, which substitutes (z-1) / (z+1)
for s
, maintaining the shape of the frequency response.
Numerator of the analog filter transfer function.
Denominator of the analog filter transfer function.
Sample rate, as ordinary frequency (e.g., hertz). No prewarping is done in this function.
Numerator of the transformed digital filter transfer function.
Denominator of the transformed digital filter transfer function.
Return a digital IIR filter from an analog one using a bilinear transform.
>>> from scipy import signal
... import matplotlib.pyplot as plt
>>> fs = 100
... bf = 2 * np.pi * np.array([7, 13])
... filts = signal.lti(*signal.butter(4, bf, btype='bandpass',
... analog=True))
... filtz = signal.lti(*signal.bilinear(filts.num, filts.den, fs))
... wz, hz = signal.freqz(filtz.num, filtz.den)
... ws, hs = signal.freqs(filts.num, filts.den, worN=fs*wz)
>>> plt.semilogx(wz*fs/(2*np.pi), 20*np.log10(np.abs(hz).clip(1e-15)),See :
... label=r'$|H_z(e^{j \omega})|$')
... plt.semilogx(wz*fs/(2*np.pi), 20*np.log10(np.abs(hs).clip(1e-15)),
... label=r'$|H(j \omega)|$')
... plt.legend()
... plt.xlabel('Frequency [Hz]')
... plt.ylabel('Magnitude [dB]')
... plt.grid()
The following pages refer to to this document either explicitly or contain code examples using this.
scipy.signal._filter_design.bilinear_zpk
scipy.signal._filter_design.lp2hp_zpk
scipy.signal._filter_design.lp2hp
scipy.signal._filter_design.lp2lp
scipy.signal._filter_design.lp2bp_zpk
scipy.signal._filter_design.lp2bs
scipy.signal._filter_design.lp2bp
scipy.signal._filter_design.lp2bs_zpk
scipy.signal._filter_design.bilinear
scipy.signal._filter_design.lp2lp_zpk
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