Calculate abs from input signals before it is squared

Author: EITOKU Hiroaki

commpy/channels.py

@@ -90,7 +90,7 @@ 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)