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detect: refactor receiver for large frequency drifts (~0.1%)

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Roman Zeyde
2015-01-15 18:14:16 +02:00
parent 5401206178
commit 1da258ebf8
5 changed files with 74 additions and 53 deletions
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20
tests/test_detect.py
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@@ -7,6 +7,7 @@ from amodem import detect
from amodem import equalizer
from amodem import sampling
from amodem import config
from amodem import common
config = config.fastest()
@@ -15,9 +16,10 @@ def test_detect():
t = np.arange(P * config.Nsym) * config.Ts
x = np.cos(2 * np.pi * config.Fc * t)
detector = detect.Detector(config)
samples, amp = detector.run(x)
detector = detect.Detector(config, pylab=common.Dummy())
samples, amp, freq_err = detector.run(x)
assert abs(1 - amp) < 1e-12
assert abs(freq_err) < 1e-16
x = np.cos(2 * np.pi * (2*config.Fc) * t)
with pytest.raises(ValueError):
@@ -36,9 +38,8 @@ def test_prefix():
def symbols_stream(signal):
sampler = sampling.Sampler(signal)
return dsp.Demux(sampler=sampler, omegas=[omega], Nsym=config.Nsym)
r = recv.Receiver(config)
freq_err = r._prefix(symbols_stream(signal))
assert abs(freq_err) < 1e-16
r = recv.Receiver(config, pylab=common.Dummy())
r._prefix(symbols_stream(signal))
with pytest.raises(ValueError):
silence = 0 * signal
@@ -47,15 +48,14 @@ def test_prefix():
def test_find_start():
sym = np.cos(2 * np.pi * config.Fc * np.arange(config.Nsym) * config.Ts)
detector = detect.Detector(config)
detector = detect.Detector(config, pylab=common.Dummy())
length = 200
prefix = postfix = np.tile(0 * sym, 50)
carrier = np.tile(sym, length)
for offset in range(10):
prefix = [0] * offset
bufs = [prefix, prefix, carrier, postfix]
for offset in range(32):
bufs = [prefix, [0] * offset, carrier, postfix]
buf = np.concatenate(bufs)
start = detector.find_start(buf, length*config.Nsym)
start = detector.find_start(buf, length)
expected = offset + len(prefix)
assert expected == start