def pitch_filter_bank(ratios_pitches=None, fs=16000, Q=25.0, max_loss_pass=1.0, min_attenuation_stop=50.0):
"""
lowest pitch: 20.6 Hz = pitch 16, the lowest pitch above the low threshold of hearing
highest pitch: 7458.6 Hz = pitch 118, the highest pitch below half of the sampling frequency (fs = 16000Hz)
Note that 119 is technically below the nyquist frequency (~7900Hz), but the right stopband frequency wouldn't be.
fs: sampling frequency of the input in Hz
Q: Q factor = frequency / bandwidth, used to determine passband and stopband frequencies of the elliptic filters
max_loss_pass: maximal loss in passband in dB
min_attenuation_stop: minimal attenuation in stopband in dB
"""
if ratios_pitches is None:
ratios_pitches = RATIOS_PITCHES_DEFAULT
# structure: tuples of sampling frequency ratios and sets of pitches
filters = {} # dictionary indexed by sampling frequency ratio. Each item is again a dictionary indexed by pitch, giving a filter coefficient tuple.
for ratio, pitches in ratios_pitches:
filters[ratio] = {}
current_fs = float(fs / ratio) # input sampling frequency for the current set of pitches
nyquist_freq = current_fs / 2
for pitch in pitches:
freq = pitch2freq(pitch)
w = freq / nyquist_freq # omega = normalised frequency
w_pass = (w * (1 - 1 / (2*Q)), w * (1 + 1 / (2*Q)))
w_stop = (w * (1 - 1 / Q), w * (1 + 1 / Q))
n, w_natural = sig.ellipord(w_pass, w_stop, max_loss_pass, min_attenuation_stop)
coeff_b, coeff_a = sig.ellip(n, max_loss_pass, min_attenuation_stop, w_natural, btype='bandpass') # get filter coefficients
# note that scipy's ellip differs from matlab's in that it will always generate a lowpass filter by default.
# btype='bandpass' needs to be passed explicitly!
filters[ratio][pitch] = (coeff_b, coeff_a)
return filters
def __parameters_custom_order(self):
order = self.custom_order
if self.approx_type == 'butterworth':
N, self.wn = signal.buttord(self.wp,
self.ws,
self.template.att_p,
self.template.att_s,
analog=True)
N_norm, self.wn_N = signal.buttord(self.template.omega_pN,
self.template.omega_sN,
self.template.att_p,
self.template.att_s,
analog=True)
elif self.approx_type == 'bessel':
pass
elif self.approx_type == 'cheby_1':
N, self.wn = signal.cheb1ord(self.wp,
self.ws,
self.template.att_p,
self.template.att_s,
analog=True)
N_norm, self.wn_N = signal.cheb2ord(self.template.omega_pN,
self.template.omega_sN,
self.template.att_p,
self.template.att_s,
analog=True)
elif self.approx_type == 'cheby_2':
N, self.wn = signal.cheb2ord(self.wp,
self.ws,
self.template.att_p,
self.template.att_s,
analog=True)
N_norm, self.wn_N = signal.cheb2ord(self.template.omega_pN,
self.template.omega_sN,
self.template.att_p,
self.template.att_s,
analog=True)
elif self.approx_type == 'legendre':
pass
elif self.approx_type == 'gauss':
pass
elif self.approx_type == 'cauer':
N, self.wn = signal.ellipord(self.wp,
self.ws,
self.template.att_p,
self.template.att_s,
analog=True)
N_norm, self.wn_N = signal.ellipord(self.template.omega_pN,
self.template.omega_sN,
self.template.att_p,
self.template.att_s,
analog=True)
return order
def filter_emg(data: np.array, fs: int, Rs: int, notch: bool):
N, fn = signal.ellipord([46.0, 54.0], [47.0, 53], .01, Rs, fs=fs)
be, ae = signal.ellip(N, .01, Rs, fn, fs=fs, btype='bandstop')
N, fn = signal.ellipord([96, 104.0], [97, 103], .01, Rs, fs=fs)
be_100, ae_100 = signal.ellip(N, .01, Rs, fn, fs=fs, btype='bandstop')
N, fn = signal.cheb2ord(15, 10, .0086, 55, fs=500)
bb, ab = signal.cheby2(N, 50, fn, 'high', fs=fs)
signal_filtered = signal.lfilter(
be_100, ae_100, signal.lfilter(be, ae, signal.lfilter(bb, ab, data)))
# signal_filtered = data
signal_filtered_zero_ph = signal.filtfilt(
be_100, ae_100, signal.filtfilt(be, ae, signal.filtfilt(bb, ab, data)))
return signal_filtered, signal_filtered_zero_ph
def _sos(self, sfreq):
nyq = sfreq / 2.
low_stop, low_pass, high_pass, high_stop, gpass, gstop = self.args
if high_stop is None:
assert low_stop is not None
assert high_pass is None
else:
high_stop /= nyq
high_pass /= nyq
if low_stop is None:
assert low_pass is None
else:
low_pass /= nyq
low_stop /= nyq
if low_stop is None:
btype = 'lowpass'
wp, ws = high_pass, high_stop
elif high_stop is None:
btype = 'highpass'
wp, ws = low_pass, low_stop
else:
btype = 'bandpass'
wp, ws = (low_pass, high_pass), (low_stop, high_stop)
order, wn = signal.ellipord(wp, ws, gpass, gstop)
return signal.ellip(order, gpass, gstop, wn, btype, output='sos')
def data_hpass(self, x, Wp, srate):
''' High-pass filter '''
Wp = float(Wp*2/srate)
Ws = Wp*float(self.lineEdit_19.text())
Rp = float(self.lineEdit_17.text())
Rs = float(self.lineEdit_18.text())
tempstring = self.lineEdit_16.text()
if tempstring == 'auto':
if self.comboBox_2.currentIndex() == 0:
(norder, Wn) = buttord(Wp, Ws, Rp, Rs)
elif self.comboBox_2.currentIndex() == 1:
(norder, Wn) = ellipord(Wp, Ws, Rp, Rs)
else:
(norder, Wn) = cheb1ord(Wp, Ws, Rp, Rs)
else:
norder = float(tempstring)
Wn = Wp
if self.comboBox_2.currentIndex() == 0:
(b, a) = butter(norder, Wn, btype = 'high')
elif self.comboBox_2.currentIndex() == 1:
(b, a) = ellip(norder, Rp, Rs, Wn)
else:
(b, a) = cheby1(norder, Rp, Wn)
y = filtfilt(b, a, x)
return(y)
def _get_filter_coeffs(self, output='sos', analog=False):
from scipy import signal
# Compute the filter params
N, Wn = signal.ellipord(
wp=self._f_pass,
ws=self._f_stop,
gpass=self._max_suppression_pass,
gstop=self._min_suppression_stop,
analog=False,
fs=self._f_sample
)
if analog:
fs = None
else:
fs = self._f_sample
coeffs = signal.ellip(
N,
rp=self._max_suppression_pass,
rs=self._min_suppression_stop,
Wn=Wn,
btype=self._kind,
analog=analog,
output=output,
fs=fs
)
return coeffs
def design_filter(self, fs):
if np.isinf(self.LPFcutoff):
N, Ws = ellipord(self.HPFcutoff * 1e3 / fs * 2,
max(5 * 1e3 / fs * 2,
(self.HPFcutoff - 5) * 1e3 / fs * 2),
self.Rp,
self.Rs)
b, a = ellip(N, self.Rp, self.Rs, Ws, 'high')
else:
N, Ws = ellipord([self.HPFcutoff * 1e3 / fs * 2, self.LPFcutoff * 1e3 / fs * 2],
[max(5*1e3/fs*2,(self.HPFcutoff-5)*1e3/fs*2),
min((fs/2-5e3)/fs*2,(self.LPFcutoff+5)*1e3/fs*2)],
self.Rp,
self.Rs)
b, a = ellip(N, self.Rp, self.Rs, Ws)
return b, a
def NmaxCauer(Qmax):
wp = 1
ws =
gpass =
gstop =
N, Wn = signal.ellipord(wp,ws,gpass,gstop,analog = True)
return N
def LPmin(self, fil_dict):
"""Elliptic LP filter, minimum order"""
self.get_params(fil_dict)
self.N, self.F_PBC = ellipord(self.F_PB,self.F_SB, self.A_PB,self.A_SB,
analog = self.analog)
self.save(fil_dict, sig.ellip(self.N, self.A_PB, self.A_SB, self.F_PBC,
btype='low', analog = self.analog, output = frmt))
def BPmin(self, fil_dict):
"""Elliptic BP filter, minimum order"""
self.get_params(fil_dict)
self.N, self.F_PBC = ellipord([self.F_PB, self.F_PB2],
[self.F_SB, self.F_SB2], self.A_PB, self.A_SB, analog = self.analog)
self.save(fil_dict, sig.ellip(self.N, self.A_PB, self.A_SB, self.F_PBC,
btype='bandpass', analog = self.analog, output = frmt))
def get_filter(spec, filter_type='but', method='zoh'):
if filter_type.lower() in ('butterworth'):
N, Wn = signal.buttord(2*np.pi*spec['fp'], 2*np.pi*spec['fs'], spec['Amax'], spec['Amin'], analog=True)
z, p, k = signal.butter(N, Wn, output='zpk', btype='low', analog=True)
elif filter_type.lower() in ('cauer' + 'elliptic'):
N, Wn = signal.ellipord(2*np.pi*fp, 2*np.pi*spec['fs'], spec['Amax'], spec['Amin'], analog=True)
z, p, k = signal.ellip(N, spec['Amax'], spec['Amin'], Wn, output='zpk', btype='low', analog=True)
def matched_method(z, p, k, dt):
zd = np.exp(z*dt)
pd = np.exp(p*dt)
kd = k * np.abs(np.prod(1-pd)/np.prod(1-zd) * np.prod(z)/np.prod(p))
return zd, pd, kd, dt
if method == 'matched':
zd, pd, kd, dt = matched_method(z, p, k, spec['dt'])
kd *= 1 - (1 - 10 ** (-spec['Amax']/20))/2
else:
zd, pd, kd, dt = signal.cont2discrete((z,p,k), spec['dt'], method=method)
analog_system = (z,p,k)
discrete_system = (zd,pd,kd)
return analog_system, discrete_system
def get_filter(spec, filter_type='but', method='zoh'):
wp = 2*np.pi*spec['fp']
ws = 2*np.pi*spec['fs']
if method == 'bilinear':
wp = 2/spec['dt'] * np.arctan(wp * spec['dt']/2)
ws = 2/spec['dt'] * np.arctan(ws * spec['dt']/2)
if filter_type.lower() in ('butterworth'):
N, Wn = signal.buttord(wp, ws, spec['Amax'], spec['Amin'], analog=True)
z, p, k = signal.butter(N, Wn, output='zpk', btype='low', analog=True)
elif filter_type.lower() in ('cauer' + 'elliptic'):
N, Wn = signal.ellipord(wp, ws, spec['Amax'], spec['Amin'], analog=True)
z, p, k = signal.ellip(N, spec['Amax'], spec['Amin'], Wn, output='zpk', btype='low', analog=True)
if method == 'matched':
zd, pd, kd, dt = matched_method(z, p, k, spec['dt'])
kd *= 1 - (1 - 10 ** (-spec['Amax']/20))/2
else:
zd, pd, kd, dt = signal.cont2discrete((z,p,k), spec['dt'], method=method)
analog_system = (z,p,k)
discrete_system = (zd,pd,kd)
return analog_system, discrete_system
def ellip_bp(atten, ripple, lo=0, hi=0, hp_width=0, lp_width=0, Fs=2.0):
if hp_width == 0 and lo > 0:
hp_width = 0.1 * (hi - lo)
if lo - hp_width <= 0:
# set hp_width to halfway between 0 and lo
hp_width = 0.5 * lo
print('bad HP stopband, adjusting to {0:.1f}'.format(hp_width))
if lp_width == 0 and hi > 0:
lp_width = 0.1 * (hi - lo)
if hi + lp_width >= Fs / 2:
# make lp_width to halfway between hi and Nyquist
lp_width = 0.5 * (Fs / 2 - hi)
print('bad LP stopband, adjusting to {0:.1f}'.format(lp_width))
if lo > 0 and hi > 0:
# bandpass design
wp = np.array([lo, hi]) * 2 / Fs
ws = np.array([lo - hp_width, hi + lp_width]) * 2 / Fs
btype = 'bandpass'
elif lo > 0:
# highpass design
wp = 2 * lo / Fs
ws = 2 * (lo - hp_width) / Fs
btype = 'highpass'
elif hi > 0:
# lowpass design
wp = 2 * hi / Fs
ws = 2 * (hi + lp_width) / Fs
btype = 'lowpass'
order, wn = signal.ellipord(wp, ws, ripple, atten)
return signal.ellip(order, ripple, atten, wn, btype=btype)
def _sos(self, sfreq):
nyq = sfreq / 2.
low_stop, low_pass, high_pass, high_stop, gpass, gstop = self.args
if high_stop is None:
assert low_stop is not None
assert high_pass is None
else:
high_stop /= nyq
high_pass /= nyq
if low_stop is None:
assert low_pass is None
else:
low_pass /= nyq
low_stop /= nyq
if low_stop is None:
btype = 'lowpass'
wp, ws = high_pass, high_stop
elif high_stop is None:
btype = 'highpass'
wp, ws = low_pass, low_stop
else:
btype = 'bandpass'
wp, ws = (low_pass, high_pass), (low_stop, high_stop)
order, wn = signal.ellipord(wp, ws, gpass, gstop)
return signal.ellip(order, gpass, gstop, wn, btype, output='sos')
def _sos(self, sfreq):
nyq = sfreq / 2.
low_stop, low_pass, high_pass, high_stop, gpass, gstop = self.args
order, wn = signal.ellipord((low_pass / nyq, high_pass / nyq),
(low_stop / nyq, high_stop / nyq), gpass,
gstop)
return signal.ellip(order, gpass, gstop, wn, 'bandpass', output='sos')
def ellip_bp(fs, fm, B, rpass, gstop):
fpass = np.array([fm - B / 2, fm + B / 2])
fstop = np.array([fm - B / 2 - 0.1 * B, fm + B / 2 + 0.1 * B])
wpass = 2 * fpass / fs
wstop = 2 * fstop / fs
[order, wn] = signal.ellipord(wpass, wstop, rpass, gstop)
sos = signal.ellip(order, rpass, gstop, wn, btype='bandpass', output='sos')
return sos
def data_lpass(self, x, Wp, srate):
''' Low-pass filter using various filter type '''
tempstring = self.lineEdit_16.text()
if tempstring == 'auto':
Wp = float(Wp*2/srate)
Ws = Wp*float(self.lineEdit_19.text())
Rp = float(self.lineEdit_17.text())
Rs = float(self.lineEdit_18.text())
if self.comboBox_2.currentIndex() == 0:
(norder, Wn) = buttord(Wp, Ws, Rp, Rs)
elif self.comboBox_2.currentIndex() == 1:
(norder, Wn) = ellipord(Wp, Ws, Rp, Rs)
else:
(norder, Wn) = cheb1ord(Wp, Ws, Rp, Rs)
else:
norder = float(tempstring)
Wp = float(Wp*2/srate)
Ws = Wp*2
self.lineEdit_19.setText(str(Ws/Wp))
Rp = 3
self.lineEdit_17.setText(str(Rp))
Rs = 0.3*norder*20
self.lineEdit_18.setText(str(Rs))
if self.comboBox_2.currentIndex() == 0:
(norder, Wn) = buttord(Wp, Ws, Rp, Rs)
elif self.comboBox_2.currentIndex() == 1:
(norder, Wn) = ellipord(Wp, Ws, Rp, Rs)
else:
(norder, Wn) = cheb1ord(Wp, Ws, Rp, Rs)
if self.comboBox_2.currentIndex() == 0:
(b, a) = butter(norder, Wn)
elif self.comboBox_2.currentIndex() == 1:
(b, a) = ellip(norder, Rp, Rs, Wn)
else:
(b, a) = cheby1(norder, Rp, Wn)
y = filtfilt(b, a, x)
return(y)
def BPmin(self, fil_dict):
"""Elliptic BP filter, minimum order"""
self._get_params(fil_dict)
self.N, self.F_PBC = ellipord([self.F_PB, self.F_PB2],
[self.F_SB, self.F_SB2], self.A_PB, self.A_SB, analog=self.analog)
if not self._test_N():
return -1
self._save(fil_dict, sig.ellip(self.N, self.A_PB, self.A_SB, self.F_PBC,
btype='bandpass', analog=self.analog, output=self.FRMT))
def ellip_spec(f0, f1, M):
"""Compute full spectrum of backwards/forwards high-pass elliptic
filter."""
gpass = 0.01
gstop = 40
N, Wn = ellipord(f0, f1, gpass, gstop, fs=1)
b, a = ellip(N, gpass, gstop, Wn, 'high', fs=1)
f, H = freqz(b, a, fs=1, whole=True, worN=M)
return np.abs(H*H)
def BPmin(self, fil_dict):
"""Elliptic BP filter, minimum order"""
self._get_params(fil_dict)
self.N, self.F_PBC = ellipord([self.F_PB, self.F_PB2],
[self.F_SB, self.F_SB2], self.A_PB, self.A_SB, analog=self.analog)
if not self._test_N():
return -1
self._save(fil_dict, sig.ellip(self.N, self.A_PB, self.A_SB, self.F_PBC,
btype='bandpass', analog=self.analog, output=self.FRMT))
def bessel(self, save=True, show=False):
N, Wn = signal.ellipord(self.Wpass, self.Wstop, self.gpass, self.gstop)
b, a = signal.bessel(N, Wn, 'low')
y = signal.filtfilt(b, a, self.output)
if show:
self.showGraph(data=y)
if save:
self.output = y
def ellip_bf(x, f0, f1):
"""backwards/forwards elliptic filter"""
gpass = 0.01
gstop = 40
N, Wn = ellipord(f0, f1, gpass, gstop, fs=1)
b, a = ellip(N, gpass, gstop, Wn, 'high', fs=1)
x2 = lfilter(b, a, x[::-1])
x3 = lfilter(b, a, x2[::-1])
return x3
def compute_parameters(self, target='stopband'):
""" This function computes the order and the -3 dB-frequency
of the filter for the specific parameters.
Arguments:
target: The optimization goal for the filter computation.
Choices are:
- stopband: optimize to the stopband (like MATLAB)
- passband: optimize to the passband
"""
if target not in ['passband', 'stopband', None]:
raise ValueError("Target must be one of passband or stopband, \
or not given if filter is not Butterworth.")
else:
self.filter_target = target
if True: # Change here to be more verbose.
print("Ws = ", self.Ws)
print("Wp = ", self.Wp)
print("Rp = ", self.passband_attenuation)
print("Rs = ", self.stopband_attenuation)
if self.filter_class == 'butterworth':
if target == 'passband':
self.N, self.Wn = signal.buttord(self.Wp, self.Ws,
self.passband_attenuation,
self.stopband_attenuation,
analog=True)
elif target == 'stopband':
self.N, self.Wn = custom.custom_buttord(self.Wp, self.Ws,
self.passband_attenuation,
self.stopband_attenuation,
analog=True)
else:
raise ValueError("Butterworth filters must match either the \
passband or the stopband.")
elif self.filter_class == 'chebyshev_1':
self.N, self.Wn = signal.cheb1ord(self.Wp, self.Ws,
self.passband_attenuation,
self.stopband_attenuation,
analog=True)
elif self.filter_class == 'chebyshev_2':
self.N, self.Wn = signal.cheb2ord(self.Wp, self.Ws,
self.passband_attenuation,
self.stopband_attenuation,
analog=True)
elif self.filter_class == 'elliptical':
self.N, self.Wn = signal.ellipord(self.Wp, self.Ws,
self.passband_attenuation,
self.stopband_attenuation,
analog=True)
else:
raise NotImplementedError(
"Filter family {} not yet implemented".format(self.filter_class))
pass
def test_ellipord_4(self):
# Test case for bandstop filter
ORD = IIRDesign.ellipord(self.f4, self.f3, self.Rp, self.Rs)
ord = signal.ellipord(self.f4,
self.f3,
self.Rp,
self.Rs,
analog=False,
fs=2)
self.assertTrue((ORD[0] == ord[0]) and np.all(ORD[1] == ord[1]))
def HPmin(self, fil_dict):
"""Elliptic HP filter, minimum order"""
self._get_params(fil_dict)
self.N, self.F_PBC = ellipord(self.F_PB,self.F_SB, self.A_PB,self.A_SB,
analog=self.analog)
# force even N
if (self.N%2)== 1:
self.N += 1
self._save(fil_dict, sig.ellip(self.N, self.A_PB, self.A_SB, self.F_PBC,
btype='highpass', analog=self.analog, output=self.FRMT))
def test_ellipord_2(self):
# Test case for highpass filter
ORD = IIRDesign.ellipord(self.f2, self.f1, self.Rp, self.Rs)
ord = signal.ellipord(self.f2,
self.f1,
self.Rp,
self.Rs,
analog=False,
fs=2)
self.assertTrue((ORD[0] == ord[0]) and np.all(ORD[1] == ord[1]))
def BSmin(self, fil_dict):
"""Elliptic BP filter, minimum order"""
self._get_params(fil_dict)
self.N, self.F_PBC = ellipord([self.F_PB, self.F_PB2],
[self.F_SB, self.F_SB2], self.A_PB,self.A_SB,
analog=self.analog)
# force even N
if (self.N%2)== 1:
self.N += 1
self._save(fil_dict, sig.ellip(self.N, self.A_PB, self.A_SB, self.F_PBC,
btype='bandstop', analog=self.analog, output=self.FRMT))
def BPmin(self, fil_dict):
"""Elliptic BP filter, minimum order"""
self._get_params(fil_dict)
self.N, self.F_PBC = ellipord([self.F_PB, self.F_PB2],
[self.F_SB, self.F_SB2], self.A_PB, self.A_SB, analog=self.analog)
#logger.warning(" "+str(self.F_PBC) + " " + str(self.N))
if (self.N%2)== 1:
self.N += 1
#logger.warning("-"+str(self.F_PBC) + " " + str(self.A_SB))
self._save(fil_dict, sig.ellip(self.N, self.A_PB, self.A_SB, self.F_PBC,
btype='bandpass', analog=self.analog, output=self.FRMT))
def LPmin(self, fil_dict):
"""Elliptic LP filter, minimum order"""
self._get_params(fil_dict)
self.N, self.F_PBC = ellipord(self.F_PB,self.F_SB, self.A_PB,self.A_SB,
analog=self.analog)
# force even N
if (self.N%2)== 1:
self.N += 1
#logger.warning("and "+str(self.F_PBC) + " " + str(self.N))
self._save(fil_dict, sig.ellip(self.N, self.A_PB, self.A_SB, self.F_PBC,
btype='low', analog=self.analog, output=self.FRMT))
def __order_min_max_cauer(self):
N, self.wn = signal.ellipord(self.wp,
self.ws,
self.template.att_p,
self.template.att_s,
analog=True)
N_norm, self.wn_N = signal.ellipord(self.template.omega_pN,
self.template.omega_sN,
self.template.att_p,
self.template.att_s,
analog=True)
if N < self.min_order:
order = self.min_order
elif N > self.max_order:
order = self.max_order
else:
order = N
return order
def BSmin(self, fil_dict):
"""Elliptic BP filter, minimum order"""
self._get_params(fil_dict)
self.N, self.F_PBC = ellipord([self.F_PB, self.F_PB2],
[self.F_SB, self.F_SB2], self.A_PB,self.A_SB, analog=self.analog)
# force even N
if (self.N%2)== 1:
self.N += 1
if not self._test_N():
return -1
self._save(fil_dict, sig.ellip(self.N, self.A_PB, self.A_SB, self.F_PBC,
btype='bandstop', analog=self.analog, output=self.FRMT))
def get_ellip_bp2():
"""Elliptical filter frequency response."""
wp = [1 / 19.0, 1 / 9.0]
ws = [1 / 21.0, 1 / 8.0]
gpass = 0.01
gstop = 40
N, Wn = ellipord(wp, ws, gpass, gstop, fs=1)
b, a = ellip(N, gpass, gstop, Wn, 'bandpass', fs=1)
fs = 1
M = 512
f, H = freqz(b, a, fs=fs, worN=M)
return f, H
def LPmin(self, fil_dict):
"""Elliptic LP filter, minimum order"""
self._get_params(fil_dict)
self.N, self.F_PBC = ellipord(self.F_PB,self.F_SB, self.A_PB,self.A_SB, analog=self.analog)
# force even N
if (self.N%2)== 1:
self.N += 1
if not self._test_N():
return -1
#logger.warning("and "+str(self.F_PBC) + " " + str(self.N))
self._save(fil_dict, sig.ellip(self.N, self.A_PB, self.A_SB, self.F_PBC,
btype='low', analog=self.analog, output=self.FRMT))
def get_ellip_h1():
"""Elliptical filter frequency response."""
wp = 1 / 7.0
ws = 1 / 8.0
gpass = 0.01
gstop = 40
N, Wn = ellipord(wp, ws, gpass, gstop, fs=1)
b, a = ellip(N, gpass, gstop, Wn, 'high', fs=1)
fs = 1
M = 512
f, H = freqz(b, a, fs=fs, worN=M)
return f, H
def highPassIIRellip(wav_file_path, plot_interval, verbose=False):
# ------------------------------------------------
# Create a signal.
# ------------------------------------------------
samplerate, x = wavfile.read(wav_file_path)
nsamples = x.size
t = arange(nsamples) / samplerate
# ------------------------------------------------
# Create a IIR filter and apply it to x.
# ------------------------------------------------
N, Wn = ellipord(wp=0.5, ws=0.45, gstop=60, gpass=1)
b, a = ellip(N, 1, 60, Wn, btype='high')
w, h = freqz(b, a, fs=240000)
fig = plt.figure()
h_dB = 20 * np.log10(np.abs(h))
plt.plot(w, h_dB, 'b-')
#plt.ylim(-150, 5)
plt.ylabel('Magnitude (dB)')
plt.xlabel('Frequency (Hz)')
plt.grid(True)
fig.savefig('results_a6/ellip_frequency_response.png', bbox_inches='tight')
# Apply filtfilt to signal
filtered_x = lfilter(b, a, x)
wavfile.write('looneytunes_IIR_HP_6K.filtered_wav', samplerate, filtered_x)
fig = plt.figure()
# Plot the original signal.
plt.subplot(2, 1, 1)
plt.title('Original')
plt.plot(t, x, 'b-', linewidth=0.5)
plt.xlabel('Time (s)')
plt.xlim(plot_interval)
plt.ylim(-20500, 20500)
plt.grid(True)
# Plot the filtered signal, shifted to compensate for the phase delay.
plt.subplot(2, 1, 2)
plt.title('Filtered')
plt.plot(t, filtered_x, 'g', linewidth=0.5)
plt.xlim(plot_interval)
plt.ylim(-20500, 20500)
plt.xlabel('Time (s)')
plt.grid(True)
plt.subplots_adjust(hspace=0.7)
fig.savefig('results_a6/ellip_filtered_output.png', bbox_inches='tight')
if verbose:
plt.show()
def BPmin(self, fil_dict):
"""Elliptic BP filter, minimum order"""
self._get_params(fil_dict)
self.N, self.F_PBC = ellipord([self.F_PB, self.F_PB2],
[self.F_SB, self.F_SB2], self.A_PB, self.A_SB, analog=self.analog)
#logger.warning(" "+str(self.F_PBC) + " " + str(self.N))
if (self.N%2)== 1:
self.N += 1
if not self._test_N():
return -1
#logger.warning("-"+str(self.F_PBC) + " " + str(self.A_SB))
self._save(fil_dict, sig.ellip(self.N, self.A_PB, self.A_SB, self.F_PBC,
btype='bandpass', analog=self.analog, output=self.FRMT))
def ellip_bp():
fs = 48e3
fpass = np.array([300, 4500])
fstop = np.array([0, 5000])
gpass = 1
gstop = 60
wpass = 2 * fpass / fs
wstop = 2 * fstop / fs
[order, wn] = signal.ellipord(wpass, wstop, gpass, gstop)
print(wn)
sos = signal.ellip(order, gpass, gstop, wn, btype='bandpass', output='sos')
return sos
def design(params):
while(1): # Loop until we're happy with our parameters
print(params)
wp = params['wp']
ws = params['ws']
gstop = params['gstop']
gpass = params['gpass']
if wp < ws:
btype = 'lowpass'
else:
btype = 'highpass'
print(f'This is a {btype} filter.')
# Calculate the orders of each filter type
cheby1 = sig.cheb1ord(
params['wp'], params['ws'], params['gpass'], params['gstop'])
cheby2 = sig.cheb2ord(
params['wp'], params['ws'], params['gpass'], params['gstop'])
butter = sig.buttord(
params['wp'], params['ws'], params['gpass'], params['gstop'])
elliptic = sig.ellipord(
params['wp'], params['ws'], params['gpass'], params['gstop'])
x = int(input(F'''Please select an implementation:
1: Chebyshev type I ({cheby1[0]} order, corner at {cheby1[1]*nyquist} Hz)
2: Chebyshev type II ({cheby2[0]} order, corner at {cheby2[1]*nyquist} Hz)
3: Butterworth ({butter[0]} order, corner at {butter[1]*nyquist} Hz)
4: Elliptic ({elliptic[0]} order, corner at {elliptic[1]*nyquist} Hz)
5: Choose new design constraints
6: Quit
'''))
if x == 1:
sos = sig.cheby1(N=cheby1[0], rp=params['gpass'] , Wn=cheby1[1],
btype=btype, output='sos' )
elif x == 2:
sos = sig.cheby2(N=cheby2[0], rs=params['gstop'] , Wn=cheby2[1],
btype=btype, output='sos' )
elif x == 3:
sos = sig.butter(N=butter[0], Wn=butter[1],
btype=btype, output='sos' )
elif x == 4:
sos = sig.ellip(N=elliptic[0], rp=params['gpass'], rs=params['gstop'],
Wn=elliptic[1], btype=btype, output='sos' )
elif x==5:
params = get_params()
continue
else:
exit()
return(sos,params) #Break out of the loop
def LPmin(self, fil_dict):
"""Elliptic LP filter, minimum order"""
self._get_params(fil_dict)
self.N, self.F_PBC = ellipord(self.F_PB,
self.F_SB,
self.A_PB,
self.A_SB,
analog=self.analog)
self._save(
fil_dict,
sig.ellip(self.N,
self.A_PB,
self.A_SB,
self.F_PBC,
btype='low',
analog=self.analog,
output=self.FRMT))
def HPmin(self, fil_dict):
"""Elliptic HP filter, minimum order"""
self.get_params(fil_dict)
self.N, self.F_PBC = ellipord(self.F_PB,
self.F_SB,
self.A_PB,
self.A_SB,
analog=self.analog)
self.save(
fil_dict,
sig.ellip(self.N,
self.A_PB,
self.A_SB,
self.F_PBC,
btype='highpass',
analog=self.analog,
output=frmt))
def BSmin(self, fil_dict):
"""Elliptic BP filter, minimum order"""
self.get_params(fil_dict)
self.N, self.F_PBC = ellipord([self.F_PB, self.F_PB2],
[self.F_SB, self.F_SB2],
self.A_PB,
self.A_SB,
analog=self.analog)
self.save(
fil_dict,
sig.ellip(self.N,
self.A_PB,
self.A_SB,
self.F_PBC,
btype='bandstop',
analog=self.analog,
output=frmt))
def pitch_filter_bank(ratios_pitches=None,
fs=16000,
Q=25.0,
max_loss_pass=1.0,
min_attenuation_stop=50.0):
"""
lowest pitch: 20.6 Hz = pitch 16, the lowest pitch above the low threshold of hearing
highest pitch: 7458.6 Hz = pitch 118, the highest pitch below half of the sampling frequency (fs = 16000Hz)
Note that 119 is technically below the nyquist frequency (~7900Hz), but the right stopband frequency wouldn't be.
fs: sampling frequency of the input in Hz
Q: Q factor = frequency / bandwidth, used to determine passband and stopband frequencies of the elliptic filters
max_loss_pass: maximal loss in passband in dB
min_attenuation_stop: minimal attenuation in stopband in dB
"""
if ratios_pitches is None:
ratios_pitches = RATIOS_PITCHES_DEFAULT
# structure: tuples of sampling frequency ratios and sets of pitches
filters = {
} # dictionary indexed by sampling frequency ratio. Each item is again a dictionary indexed by pitch, giving a filter coefficient tuple.
for ratio, pitches in ratios_pitches:
filters[ratio] = {}
current_fs = float(
fs /
ratio) # input sampling frequency for the current set of pitches
nyquist_freq = current_fs / 2
for pitch in pitches:
freq = pitch2freq(pitch)
w = freq / nyquist_freq # omega = normalised frequency
w_pass = (w * (1 - 1 / (2 * Q)), w * (1 + 1 / (2 * Q)))
w_stop = (w * (1 - 1 / Q), w * (1 + 1 / Q))
n, w_natural = sig.ellipord(w_pass, w_stop, max_loss_pass,
min_attenuation_stop)
coeff_b, coeff_a = sig.ellip(
n,
max_loss_pass,
min_attenuation_stop,
w_natural,
btype='bandpass') # get filter coefficients
# note that scipy's ellip differs from matlab's in that it will always generate a lowpass filter by default.
# btype='bandpass' needs to be passed explicitly!
filters[ratio][pitch] = (coeff_b, coeff_a)
return filters
def calcFiltros(A1,A2,Wc,Wp):
plt.figure()
Nb, Wnb = signal.buttord(Wp,Wc,A1,A2,True)
Nc, Wnc = signal.cheb1ord(Wp,Wc,A1,A2,True)
Ne, Wne = signal.ellipord(Wp,Wc,A1,A2,True)
print('Butterbord Wp =' + str(Wp))
print("N = "+ str(Nb) )
print("Wn = "+ str(Wnb) )
Zb,Pb,Kb = signal.buttap(Nb)
ab,bb = signal.zpk2tf(Zb,Pb,Kb)
print("H(s) = ")
strFunTrans = funTrans([ab,bb])
print(strFunTrans)
print("\n")
wb, hb = freqs(ab, bb)
plt.semilogx(wb, abs(hb))
print('Chebychev Wp =' + str(Wp))
print("N = "+ str(Nc) )
print("Wn = "+ str(Wnc) )
Zc,Pc,Kc = signal.buttap(Nc)
ac,bc = signal.zpk2tf(Zc,Pc,Kc)
print("H(s) = ")
strFunTrans = funTrans([ac,bc])
print(strFunTrans)
print("\n")
wc, hc = freqs(ac, bc)
plt.semilogx(wc, abs(hc))
print('Eliptica Wp =' + str(Wp))
print("N = "+ str(Ne) )
print("Wn = "+ str(Wne) )
Ze,Pe,Ke = signal.buttap(Ne)
ae,be = signal.zpk2tf(Ze,Pe,Ke)
print("H(s) = ")
strFunTrans = funTrans([ae,be])
print(strFunTrans)
print("\n")
we, he = freqs(ae, be)
plt.semilogx(we, abs(he))
plt.xlabel('Frequency')
plt.ylabel('Amplitude response')
plt.grid()
def __filter_order(self):
""" Computing filters order and maximum value of X axis. """
if self.ftype == "butter":
if self.btype == 'highpass':
self.xaxis_max = 0.2
else:
self.xaxis_max = 0.15
(self.ord, self.wn) = signal.buttord(self.wp_norm,
self.ws_norm,
self.gpass,
self.gstop,
analog=True)
elif self.ftype == "cheby1":
if self.btype == 'highpass':
self.xaxis_max = 0.6
else:
self.xaxis_max = 0.15
(self.ord, self.wn) = signal.cheb1ord(self.wp_norm,
self.ws_norm,
self.gpass,
self.gstop,
analog=True)
elif self.ftype == "cheby2":
if self.btype == 'highpass':
self.xaxis_max = 0.2
else:
self.xaxis_max = 0.3
(self.ord, self.wn) = signal.cheb2ord(self.wp_norm,
self.ws_norm,
self.gpass,
self.gstop,
analog=True)
elif self.ftype == "ellip":
if self.btype == 'highpass':
self.xaxis_max = 0.6
else:
self.xaxis_max = 0.2
(self.ord, self.wn) = signal.ellipord(self.wp_norm,
self.ws_norm,
self.gpass,
self.gstop,
analog=True)
def _compute_parameters(self):
normalized_pb, normalized_sb = self.normalized_pb_sb()
self.N, self.Wn = signal.ellipord(normalized_pb, normalized_sb,
self.filter_parameters['passband_attenuation'],
self.filter_parameters['stopband_attenuation'])
self.already_normalized_Wn = True
data_suav=data #se calcula es espectro de la senal suavizada para poder ver las frecuencias que externas que pueden estar afectando la medida # por lo general la senal de ecg tiene su mayor informacion distribida entre 0 y 40 hz spectr=np.absolute(fft(data_suav)) ########################################### #### ETAPA DE FILTRADO ##### ########################################### # se disena un filtro pasa altas para poder eliminar el valor dc y tratar de atenuar frecuencias muy bajas que de acuerdo a la # literatura afecta a la senal para los propósitos que se buscan aqui # se va a usar un filtro eliptico pasa altas que provee scipy wl1=(2.0)*(1.0)/(fs) wl2=(2.0)*(0.00001)/(fs) N2,Wn2=signal.ellipord(wl1,wl2,9.0,10.0) b1,a1=signal.ellip(N2,9.0,10.0,Wn2,'high') w1,h1=signal.freqz(b1,a1,fs) # elaborado el filtro se procede a pasar la senal por este senal_high=signal.lfilter(b1,a1,data_suav) #se comienza el diseno del filtro pasabajas usando un filtro eliptico, la senal de ecg tiene su mayor informacion entre 0 y 40 hz, el filtro #pasabajas es usado con el fin de eliminar todas las componentes que esten por encima de 40 hz, adempas permite eliminar el ruido introducido # por las lineas de alimentacion que afecta las frecuencias de 50 y 60 hz wp1=(2.0)*(30.0)/(fs) wp2=(2.0)*(40.0)/(fs) N,Wn=signal.ellipord(wp1,wp2,0.01,100.0) b,a=signal.ellip(N,0.01,100.0,Wn) w,h=signal.freqz(b,a,fs,0) #disenado el filtro se hace pasar la senal por el senal_filtrada1=signal.lfilter(b,a,senal_high)
