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sigproc: fix QAM quantization

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Roman Zeyde
2014-08-10 18:07:58 +03:00
parent c08b0edf80
commit 55a7c31447
1 changed files with 12 additions and 6 deletions
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18
amodem/sigproc.py
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@@ -51,13 +51,15 @@ class QAM(object):
reals = np.array(list(sorted(set(symbols.real))))
imags = np.array(list(sorted(set(symbols.imag))))
self.real_factor = 2.0 / np.mean(np.diff(reals))
self.imag_factor = 2.0 / np.mean(np.diff(imags))
self.real_factor = 1.0 / np.mean(np.diff(reals))
self.imag_factor = 1.0 / np.mean(np.diff(imags))
self.real_offset = reals[0]
self.imag_offset = imags[0]
self.symbols_map = {}
for S in symbols:
real_index = round(S.real * self.real_factor)
imag_index = round(S.imag * self.imag_factor)
real_index = round(S.real * self.real_factor + self.real_offset)
imag_index = round(S.imag * self.imag_factor + self.imag_offset)
self.symbols_map[real_index, imag_index] = (S, self._dec[S])
def encode(self, bits):
@@ -66,11 +68,15 @@ class QAM(object):
def decode(self, symbols, error_handler=None):
real_factor = self.real_factor
real_offset = self.real_offset
imag_factor = self.imag_factor
imag_offset = self.imag_offset
symbols_map = self.symbols_map
for S in symbols:
real_index = round(S.real * real_factor)
imag_index = round(S.imag * imag_factor)
real_index = round(S.real * real_factor + real_offset)
imag_index = round(S.imag * imag_factor + imag_offset)
decoded_symbol, bits = symbols_map[real_index, imag_index]
if error_handler:
error_handler(received=S, decoded=decoded_symbol)