ASCEE/lasp
ASCEE/lasp
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Some markup improvements

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This commit is contained in:
Anne de Jong 2021-04-22 12:10:42 +02:00
parent 4e9f975aed
commit e268a55680
1 changed files with 38 additions and 34 deletions
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28
lasp/filter/biquad.py
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@ -25,9 +25,10 @@ y[n] = 1/ba[3] * ( ba[0] * x[n] + ba[1] * x[n-1] + ba[2] * x[n-2] +
__all__ = ['peaking', 'biquadTF', 'notch', 'lowpass', 'highpass', __all__ = ['peaking', 'biquadTF', 'notch', 'lowpass', 'highpass',
'highshelve', 'lowshelve'] 'highshelve', 'lowshelve']
from scipy.signal import sosfreqz from numpy import array, cos, pi, sin, sqrt
from scipy.interpolate import interp1d from scipy.interpolate import interp1d
from numpy import sin, cos, sqrt, pi, array from scipy.signal import sosfreqz
def peaking(fs, f0, Q, gain): def peaking(fs, f0, Q, gain):
""" """
@ -51,6 +52,7 @@ def peaking(fs, f0, Q, gain):
return array([b0/a0, b1/a0, b2/a0, a0/a0, a1/a0, a2/a0]) return array([b0/a0, b1/a0, b2/a0, a0/a0, a1/a0, a2/a0])
def notch(fs, f0, Q): def notch(fs, f0, Q):
""" """
Notch filter Notch filter
@ -70,6 +72,7 @@ def notch(fs, f0, Q):
a2 = 1 - alpha a2 = 1 - alpha
return array([b0/a0, b1/a0, b2/a0, a0/a0, a1/a0, a2/a0]) return array([b0/a0, b1/a0, b2/a0, a0/a0, a1/a0, a2/a0])
def lowpass(fs, f0, Q): def lowpass(fs, f0, Q):
""" """
Second order low pass filter Second order low pass filter
@ -89,6 +92,7 @@ def lowpass(fs, f0, Q):
a2 = 1 - alpha a2 = 1 - alpha
return array([b0/a0, b1/a0, b2/a0, a0/a0, a1/a0, a2/a0]) return array([b0/a0, b1/a0, b2/a0, a0/a0, a1/a0, a2/a0])
def highpass(fs, f0, Q): def highpass(fs, f0, Q):
""" """
Second order high pass filter Second order high pass filter
@ -123,14 +127,15 @@ def highshelve(fs, f0, Q, gain):
w0 = 2*pi*f0/fs w0 = 2*pi*f0/fs
alpha = sin(w0)/Q/2 alpha = sin(w0)/Q/2
A = 10**(gain/40) A = 10**(gain/40)
b0 = A*( (A+1) + (A-1)*cos(w0) + 2*sqrt(A)*alpha ) b0 = A*((A+1) + (A-1)*cos(w0) + 2*sqrt(A)*alpha)
b1 = -2*A*( (A-1) + (A+1)*cos(w0) ) b1 = -2*A*((A-1) + (A+1)*cos(w0))
b2 = A*( (A+1) + (A-1)*cos(w0) - 2*sqrt(A)*alpha ) b2 = A*((A+1) + (A-1)*cos(w0) - 2*sqrt(A)*alpha)
a0 = (A+1) - (A-1)*cos(w0) + 2*sqrt(A)*alpha a0 = (A+1) - (A-1)*cos(w0) + 2*sqrt(A)*alpha
a1 = 2*( (A-1) - (A+1)*cos(w0) ) a1 = 2*((A-1) - (A+1)*cos(w0))
a2 = (A+1) - (A-1)*cos(w0) - 2*sqrt(A)*alpha a2 = (A+1) - (A-1)*cos(w0) - 2*sqrt(A)*alpha
return array([b0/a0, b1/a0, b2/a0, a0/a0, a1/a0, a2/a0]) return array([b0/a0, b1/a0, b2/a0, a0/a0, a1/a0, a2/a0])
def lowshelve(fs, f0, Q, gain): def lowshelve(fs, f0, Q, gain):
""" """
Low shelving filter Low shelving filter
@ -144,14 +149,15 @@ def lowshelve(fs, f0, Q, gain):
w0 = 2*pi*f0/fs w0 = 2*pi*f0/fs
alpha = sin(w0)/Q/2 alpha = sin(w0)/Q/2
A = 10**(gain/40) A = 10**(gain/40)
b0 = A*( (A+1) - (A-1)*cos(w0) + 2*sqrt(A)*alpha ) b0 = A*((A+1) - (A-1)*cos(w0) + 2*sqrt(A)*alpha)
b1 = 2*A*( (A-1) - (A+1)*cos(w0) ) b1 = 2*A*((A-1) - (A+1)*cos(w0))
b2 = A*( (A+1) - (A-1)*cos(w0) - 2*sqrt(A)*alpha ) b2 = A*((A+1) - (A-1)*cos(w0) - 2*sqrt(A)*alpha)
a0 = (A+1) + (A-1)*cos(w0) + 2*sqrt(A)*alpha a0 = (A+1) + (A-1)*cos(w0) + 2*sqrt(A)*alpha
a1 = -2*( (A-1) + (A+1)*cos(w0) ) a1 = -2*((A-1) + (A+1)*cos(w0))
a2 = (A+1) + (A-1)*cos(w0) - 2*sqrt(A)*alpha a2 = (A+1) + (A-1)*cos(w0) - 2*sqrt(A)*alpha
return array([b0/a0, b1/a0, b2/a0, a0/a0, a1/a0, a2/a0]) return array([b0/a0, b1/a0, b2/a0, a0/a0, a1/a0, a2/a0])
def biquadTF(fs, freq, ba): def biquadTF(fs, freq, ba):
""" """
Computes the transfer function of the biquad. Computes the transfer function of the biquad.
@ -168,5 +174,3 @@ def biquadTF(fs, freq, ba):
freq2, h = sosfreqz(ba, worN=freq, fs=fs) freq2, h = sosfreqz(ba, worN=freq, fs=fs)
interpolator = interp1d(freq2, h, kind='quadratic') interpolator = interp1d(freq2, h, kind='quadratic')
return interpolator(freq) return interpolator(freq)