Added code to generate narrow band data from band data and vice versa

This commit is contained in:
Anne de Jong 2020-01-17 17:00:07 +01:00
parent fe53ada328
commit c748e6cb75

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@ -177,7 +177,9 @@ class FilterBankDesigner:
return list(range(xstart, xend+1))
def getNarrowBandFromOctaveBand(self, xl, xu,
levels_in_bands, npoints=500):
levels_in_bands, npoints=500,
method='flat',
scale='lin'):
"""Create a narrow band spectrum based on a spectrum in (fractional)
octave bands. The result is create such that the total energy in each
frequency band is constant. The latter can be checked by working it
@ -193,6 +195,11 @@ class FilterBankDesigner:
(xu+1 - xl)
npoints: Number of discrete frequency points in linear frequency
array.
method: 'flat' to give the same power for all frequencies in a
certain band.
scale: 'lin' for a linear frequency distribution. 'log' for a
logspace. Use 'log' with caution and only if you really know what
you are doing!'
Returns:
freq, levels_dB. Where levels_dB is an array of narrow band levels
@ -202,8 +209,16 @@ class FilterBankDesigner:
# Highest frequency of all frequencies
fuu = self.fu(xu)
if scale == 'lin':
freq = np.linspace(fll, fuu, npoints)
elif scale == 'log':
freq = np.logspace(np.log10(fll), np.log10(fuu), npoints)
else:
raise ValueError(f'Invalid scale parameter: {scale}')
levels_narrow = np.empty_like(freq)
if method == 'flat':
for i, x in enumerate(range(xl, xu + 1)):
fl = self.fl(x)
fu = self.fu(x)
@ -220,6 +235,53 @@ class FilterBankDesigner:
levels_narrow[indices_cur] = level_narrow
return freq, levels_narrow
else:
raise ValueError('Unimplemented interpolation method')
def getOctaveBandFromNarrowBand(self, freq, levels_narrow):
"""Put all level results in a certain frequency band (`binning`), by
summing up the power.
Args:
freq: Narrow-band frequency array
levels_narrow: Narrow band power levels, should be power, not *PSD*
Returns:
(fm, levels_binned, nom_txt)
"""
# Find lower frequency xl
for x in self.xs:
xl = x
fl = self.fl(x)
if self.fl(x+1) > freq[0]:
break
# Find upper frequency xu
for x in self.xs:
xu = x
fu = self.fu(xu)
if fu >= freq[-1]:
break
freq_in_bands = []
levels_in_bands = []
nom_txt = []
for x in range(xl, xu+1):
fl = self.fl(x)
fu = self.fu(x)
if x != xu:
indices_cur = np.where((freq >= fl) & (freq < fu))
else:
indices_cur = np.where((freq >= fl) & (freq <= fu))
power_cur = np.sum(10**(levels_narrow[indices_cur] / 10))
levels_in_bands.append(10*np.log10(power_cur))
nom_txt.append(self.nominal_txt(x))
freq_in_bands.append(self.fm(x))
return np.array(freq_in_bands), np.array(levels_in_bands), nom_txt
class OctaveBankDesigner(FilterBankDesigner):