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86 lines
2.1 KiB
Python
86 lines
2.1 KiB
Python
from numpy.linalg import norm
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from numpy.random import RandomState
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import numpy as np
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from amodem import dsp
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from amodem import config
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from amodem import equalizer
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def assert_approx(x, y, e=1e-12):
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assert norm(x - y) < e * norm(x)
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def test_training():
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L = 1000
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t1 = equalizer.train_symbols(L)
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t2 = equalizer.train_symbols(L)
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assert (t1 == t2).all()
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def test_commutation():
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x = np.random.RandomState(seed=0).normal(size=1000)
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b = [1, 1j, -1, -1j]
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a = [1, 0.1]
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y = dsp.lfilter(x=x, b=b, a=a)
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y1 = dsp.lfilter(x=dsp.lfilter(x=x, b=b, a=[1]), b=[1], a=a)
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y2 = dsp.lfilter(x=dsp.lfilter(x=x, b=[1], a=a), b=b, a=[1])
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assert_approx(y, y1)
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assert_approx(y, y2)
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z = dsp.lfilter(x=y, b=a, a=[1])
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z_ = dsp.lfilter(x=x, b=b, a=[1])
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assert_approx(z, z_)
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def test_modem():
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L = 1000
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sent = equalizer.train_symbols(L)
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gain = config.Nfreq
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x = equalizer.modulator(sent) * gain
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received = equalizer.demodulator(x, L)
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assert_approx(sent, received)
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def test_symbols():
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length = 100
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gain = float(config.Nfreq)
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symbols = equalizer.train_symbols(length=length)
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x = equalizer.modulator(symbols) * gain
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assert_approx(equalizer.demodulator(x, size=length), symbols)
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den = np.array([1, -0.6, 0.1])
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num = np.array([0.5])
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y = dsp.lfilter(x=x, b=num, a=den)
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lookahead = 2
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h = equalizer.equalize_symbols(
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signal=y, symbols=symbols, order=len(den), lookahead=lookahead
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)
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assert norm(h[:lookahead]) < 1e-12
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assert_approx(h[lookahead:], den / num)
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y = dsp.lfilter(x=y, b=h[lookahead:], a=[1])
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z = equalizer.demodulator(y, size=length)
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assert_approx(z, symbols)
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def test_signal():
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length = 100
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x = np.sign(RandomState(0).normal(size=length))
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den = np.array([1, -0.6, 0.1])
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num = np.array([0.5])
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y = dsp.lfilter(x=x, b=num, a=den)
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lookahead = 2
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h = equalizer.equalize_signal(
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signal=y, expected=x, order=len(den), lookahead=lookahead)
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assert norm(h[:lookahead]) < 1e-12
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h = h[lookahead:]
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assert_approx(h, den / num)
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x_ = dsp.lfilter(x=y, b=h, a=[1])
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assert_approx(x_, x)
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