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67 lines
1.5 KiB
Python
67 lines
1.5 KiB
Python
import numpy as np
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import recv
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import common
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import sigproc
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import loop
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class FreqLoop(object):
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def __init__(self, x, freq):
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self.sampler = sigproc.Sampler(x, sigproc.Interpolator())
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self.symbols = recv.extract_symbols(self.sampler, freq)
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Kp, Ki = 0.2, 0.01
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b = np.array([1, -1])*Kp + np.array([0.5, 0.5])*Ki
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self.filt = loop.Filter(b=b, a=[1])
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self.correction = 0.0
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def correct(self, actual, expected):
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self.err = np.angle(expected / actual) / np.pi
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self.err = sigproc.clip(self.err, [-0.1, 0.1])
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self.correction = self.filt(self.err)
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self.sampler.correct(offset=self.correction)
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def __iter__(self):
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return iter(self.symbols)
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import pylab
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def main():
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import sigproc
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f0 = 10e3
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_, x = common.load('recv_10kHz.pcm')
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x = x[100:]
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S = []
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Y = []
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symbols = FreqLoop(x, f0)
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prefix = 100
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for s in symbols:
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S.append(s)
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if len(S) > prefix:
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symbols.correct(s, np.mean(S[:prefix]))
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Y.append([
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symbols.correction * (f0 / common.Nsym),
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])
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S = np.array(S)
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pylab.figure()
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pylab.subplot(121)
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circle = np.exp(2j*np.pi*np.linspace(0, 1, 1001))
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pylab.plot(S.real, S.imag, '.', circle.real, circle.imag, ':')
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pylab.grid('on')
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pylab.axis('equal')
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Y = np.array(Y)
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a = 0.01
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pylab.subplot(122)
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pylab.plot(list(sigproc.lfilter([a], [1, a-1], Y)), '-')
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pylab.grid('on')
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if __name__ == '__main__':
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main()
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pylab.show()
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