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fix packet detection

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This commit is contained in:
Jinghao Shi 2017-04-14 11:01:05 -04:00
parent 701cbb70c9
commit bcee4f66a1
1 changed files with 8 additions and 8 deletions
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16
scripts/decode.py
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@ -225,13 +225,13 @@ class ChannelEstimator(object):
prod_sum += prod prod_sum += prod
beta = cmath.phase(prod_sum) beta = cmath.phase(prod_sum)
print "[PILOT OFFSET] %f (%d)" % (beta, int(beta*PHASE_SCALE)) print "[PILOT OFFSET] %f (%d)" % (beta, int(beta*PHASE_SCALE))
# beta = 0
carriers = [] carriers = []
for c in self.subcarriers: for c in self.subcarriers:
if c in PILOT_SUBCARRIES: if c in PILOT_SUBCARRIES:
continue continue
symbol[c] *= cmath.exp(complex(0, beta)) symbol[c] *= cmath.exp(complex(0, beta))
carriers.append(symbol[c] / self.gain[c]) symbol[c] /= self.gain[c]
carriers.append(symbol[c])
return carriers return carriers
def switch_ht(self): def switch_ht(self):
@ -280,7 +280,7 @@ class ChannelEstimator(object):
fine_offset = cmath.phase(sum([lts[i]*lts[i+64].conjugate() fine_offset = cmath.phase(sum([lts[i]*lts[i+64].conjugate()
for i in range(len(lts)-64)]))/64 for i in range(len(lts)-64)]))/64
print '[FINE OFFSET] %f (%d)' % (fine_offset, int(fine_offset*PHASE_SCALE)) print '[FINE OFFSET] %f (%d)' % (fine_offset, int(fine_offset*PHASE_SCALE))
# fine_offset = 0 fine_offset = 0
self.lts_samples = [c*cmath.exp(complex(0, n*fine_offset)) self.lts_samples = [c*cmath.exp(complex(0, n*fine_offset))
for n, c in enumerate(lts)] for n, c in enumerate(lts)]
@ -460,11 +460,11 @@ class Decoder(object):
Returns the index of the first sample of STS Returns the index of the first sample of STS
None if no packet was detected. None if no packet was detected.
""" """
lts = LONG_PREAMBLE[64:64+64] lts = LONG_PREAMBLE[-64:]
peaks = np.array([abs(c) for c in np.convolve( peaks = np.array([abs(c) for c in np.correlate(
samples, lts, mode='same')]).argsort()[-2:] samples, lts, mode='valid')]).argsort()[-2:]
if (max(peaks) - min(peaks) == 64) and (min(peaks) - 33 - 160) > 0: if (max(peaks) - min(peaks) == 64) and (min(peaks) - 32 - 160) > 0:
return min(peaks) - 33 - 160 return min(peaks) - 32 - 160
else: else:
return None return None