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(True) >>> plt.xlabel('Frequency [rad/s]') >>> plt.ylabel('Amplitude [dB]') >>> plt.legend() 