67 lines
1.6 KiB
Python
67 lines
1.6 KiB
Python
#!/usr/bin/env python3
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# -*- coding: utf-8 -*-
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"""!
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Author: J.A. de Jong - ASCEE
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"""
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import numpy as np
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from lasp.filter.bandpass_limits import (third_octave_band_limits,
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octave_band_limits, G, fr)
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from lasp.filter.bandpass_fir import ThirdOctaveBankDesigner, \
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OctaveBankDesigner
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import matplotlib.pyplot as plt
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# Adjust these settings
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b = 1 # or three
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zoom = False # or True
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if b == 3:
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bands = ThirdOctaveBankDesigner()
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elif b == 1:
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bands = OctaveBankDesigner()
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else:
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raise ValueError('b should be 1 or 3')
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for x in bands.xs:
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fig = plt.figure()
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ax = fig.add_subplot(111)
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fs = 48000.
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dec = np.prod(bands.decimation(x))
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fd = fs/dec
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fc = fd/2/1.4
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freq = np.logspace(np.log10(1), np.log10(fd), 5000)
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H = bands.freqResponse(fs, x, freq)
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dBH = 20*np.log10(np.abs(H))
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ax.semilogx(freq, dBH)
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if b == 1:
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freq, ulim, llim = octave_band_limits(x)
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else:
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freq, ulim, llim = third_octave_band_limits(x)
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ax.semilogx(freq, llim)
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ax.semilogx(freq, ulim)
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ax.set_title(f'x = {x}, fnom = {bands.nominal(x)}')
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if zoom:
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ax.set_xlim(bands.fl(x)/1.1, bands.fu(x)*1.1)
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ax.set_ylim(-15, 1)
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else:
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ax.set_ylim(-75, 1)
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ax.set_xlim(10, fd)
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ax.axvline(fd/2)
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if dec > 1:
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ax.axvline(fc, color='red')
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ax.legend(['Filter frequency response',
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'Lower limit from standard',
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'Upper limit from standard',
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'Nyquist frequency after decimation',
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'Decimation filter cut-off frequency'], fontsize=8)
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plt.show()
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