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Fix awgn() in channels.py #10

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Merged
veeresht merged 2 commits into from
Jun 29, 2016
Merged

Fix awgn() in channels.py #10

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428f8a7
Fix comparing operator 'is' to '=='
Jun 29, 2016
e7b053a
Calculate abs from input signals before it is squared
Jun 29, 2016
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4 changes: 2 additions & 2 deletions commpy/channels.py
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Original file line number Diff line number Diff line change
Expand Up @@ -90,11 +90,11 @@ def awgn(input_signal, snr_dB, rate=1.0):
Output signal from the channel with the specified SNR.
"""

avg_energy = sum(input_signal * input_signal)/len(input_signal)
avg_energy = sum(abs(input_signal) * abs(input_signal))/len(input_signal)
snr_linear = 10**(snr_dB/10.0)
noise_variance = avg_energy/(2*rate*snr_linear)

if input_signal.dtype is complex:
if input_signal.dtype == complex:
noise = (sqrt(noise_variance) * randn(len(input_signal))) + (sqrt(noise_variance) * randn(len(input_signal))*1j)
else:
noise = sqrt(2*noise_variance) * randn(len(input_signal))
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