ASCEE/lasp
ASCEE/lasp
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Merged improvements on SPL filter

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This commit is contained in:
Anne de Jong 2020-01-21 13:25:14 +01:00
parent 78884cbbe2
commit 183404338e
1 changed files with 38 additions and 10 deletions
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48
lasp/filter/soundpressureweighting.py
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@ -33,6 +33,14 @@ class SPLFilterDesigner:
f4 = np.sqrt((-b+np.sqrt(b**2-4*c))/2) f4 = np.sqrt((-b+np.sqrt(b**2-4*c))/2)
f4sq = f4**2 f4sq = f4**2
def __init__(self, fs):
"""Initialize a filter bank designer.
Args:
fs: Sampling frequency [Hz]
"""
self.fs = fs
def _A_uncor(self, f): def _A_uncor(self, f):
""" """
Computes the uncorrected frequency response of the A-filter Computes the uncorrected frequency response of the A-filter
@ -88,7 +96,9 @@ class SPLFilterDesigner:
return Cuncor/C1000 return Cuncor/C1000
def A_fir_design(self, fs): def A_fir_design(self):
fs = self.fs
assert int(fs) == 48000 assert int(fs) == 48000
freq_design = np.linspace(0, 17e3, 3000) freq_design = np.linspace(0, 17e3, 3000)
@ -102,7 +112,8 @@ class SPLFilterDesigner:
return fir return fir
def C_fir_design(self, fs): def C_fir_design(self):
fs = self.fs
assert int(fs) == 48000 assert int(fs) == 48000
fs = 48000. fs = 48000.
freq_design = np.linspace(0, 17e3, 3000) freq_design = np.linspace(0, 17e3, 3000)
@ -115,29 +126,46 @@ class SPLFilterDesigner:
window='rectangular') window='rectangular')
return fir return fir
def C_Sos_design(self, fs): def C_Sos_design(self):
""" """
Create filter coefficients of the C-weighting filter. Uses the bilinear Create filter coefficients of the C-weighting filter. Uses the bilinear
transform to convert the analog filter to a digital one. transform to convert the analog filter to a digital one.
Args:
fs: Sampling frequency [Hz]
Returns: Returns:
Sos: Second order sections Sos: Second order sections
""" """
fs = self.fs
p1 = 2*np.pi*self.f1 p1 = 2*np.pi*self.f1
p4 = 2*np.pi*self.f4 p4 = 2*np.pi*self.f4
zeros_analog = [0,0] zeros_analog = [0,0]
poles_analog = [p1, p1, p4, p4] poles_analog = [-p1, -p1, -p4, -p4]
k_analog = p4**2/self._C_uncor(self.fr) k_analog = p4**2/self._C_uncor(self.fr)
z, p, k = bilinear_zpk(zeros_analog, poles_analog, k_analog, fs) z, p, k = bilinear_zpk(zeros_analog, poles_analog, k_analog, fs)
sos = zpk2sos(z, p, k) sos = zpk2sos(z, p, k)
return sos return sos
# return z, p, k
# return zeros_analog, poles_analog, k_analog def A_Sos_design(self):
"""
Create filter coefficients of the A-weighting filter. Uses the bilinear
transform to convert the analog filter to a digital one.
Returns:
Sos: Second order sections
"""
fs = self.fs
p1 = 2*np.pi*self.f1
p2 = 2*np.pi*self.f2
p3 = 2*np.pi*self.f3
p4 = 2*np.pi*self.f4
zeros_analog = [0,0,0,0]
poles_analog = [-p1,-p1,-p2,-p3,-p4,-p4]
k_analog = p4**2/self._A_uncor(self.fr)
z, p, k = bilinear_zpk(zeros_analog, poles_analog, k_analog, fs)
sos = zpk2sos(z, p, k)
return sos
def show_Afir(): def show_Afir():
from asceefig.plot import Figure from asceefig.plot import Figure