`scipy.signal._filter_design:lp2bp_zpk`

source: build-install/usr/lib/python3.14/site-packages/scipy/signal/_filter_design.py:3200

Signature

def lp2bp_zpk(z, p, k, wo = 1.0, bw = 1.0)

Summary

Transform a lowpass filter prototype to a bandpass filter.

Extended Summary

Return an analog band-pass filter with center frequency wo and bandwidth bw from an analog low-pass filter prototype with unity cutoff frequency, using zeros, poles, and gain ('zpk') representation.

Parameters

z : array_like: Zeros of the analog filter transfer function.
p : array_like: Poles of the analog filter transfer function.
k : float: System gain of the analog filter transfer function.
wo : float: Desired passband center, as angular frequency (e.g., rad/s). Defaults to no change.
bw : float: Desired passband width, as angular frequency (e.g., rad/s). Defaults to 1.

Returns

z : ndarray: Zeros of the transformed band-pass filter transfer function.
p : ndarray: Poles of the transformed band-pass filter transfer function.
k : float: System gain of the transformed band-pass filter.

Notes

This is derived from the s-plane substitution

s \to \frac{s ^{2} + ω _{0} ^{2}}{s \cdot BW}

This is the "wideband" transformation, producing a passband with geometric (log frequency) symmetry about wo.

Examples

Use the 'zpk' (Zero-Pole-Gain) representation of a lowpass filter to transform it to a bandpass filter with a center frequency wo and bandwidth bw.

from scipy.signal import lp2bp_zpk
z   = [ 5 + 2j ,  5 - 2j ]
p   = [ 7      ,  -16    ]
k   = 0.8
wo  = 0.62
bw  = 15

✓

lp2bp_zpk(z, p, k, wo, bw)

✗

(array([7.49955815e+01+3.00017676e+01j, 7.49955815e+01-3.00017676e+01j,
       4.41850748e-03-1.76761126e-03j, 4.41850748e-03+1.76761126e-03j]), array([ 1.04996339e+02+0.j, -1.60167736e-03+0.j,  3.66108003e-03+0.j,
       -2.39998398e+02+0.j]), 0.8)

`scipy.signal._filter_design:lp2bp_zpk`

Signature

Summary

Extended Summary

Parameters

Returns

Notes

Examples

See also

Aliases

Referenced by

This package