scipy.signal.lp2lp#
- scipy.signal.lp2lp(b, a, wo=1.0)[source]#
Transform a lowpass filter prototype to a different frequency.
Return an analog low-pass filter with cutoff frequency wo from an analog low-pass filter prototype with unity cutoff frequency, in transfer function (‘ba’) representation.
- Parameters
- barray_like
Numerator polynomial coefficients.
- aarray_like
Denominator polynomial coefficients.
- wofloat
Desired cutoff, as angular frequency (e.g. rad/s). Defaults to no change.
- Returns
- barray_like
Numerator polynomial coefficients of the transformed low-pass filter.
- aarray_like
Denominator polynomial coefficients of the transformed low-pass filter.
Notes
This is derived from the s-plane substitution
\[s \rightarrow \frac{s}{\omega_0}\]Examples
>>> from scipy import signal >>> import matplotlib.pyplot as plt
>>> lp = signal.lti([1.0], [1.0, 1.0]) >>> lp2 = signal.lti(*signal.lp2lp(lp.num, lp.den, 2)) >>> w, mag_lp, p_lp = lp.bode() >>> w, mag_lp2, p_lp2 = lp2.bode(w)
>>> plt.plot(w, mag_lp, label='Lowpass') >>> plt.plot(w, mag_lp2, label='Transformed Lowpass') >>> plt.semilogx() >>> plt.grid() >>> plt.xlabel('Frequency [rad/s]') >>> plt.ylabel('Magnitude [dB]') >>> plt.legend()
