Return 0 for non_coherent_gain(1)

Fixes #323

src/sdr/_detection/_non_coherent_integration.py

@@ -140,6 +140,9 @@ def _non_coherent_gain_in(n_nc: float, snr: float, p_fa: float) -> float:
  """
  Solves for the non-coherent gain when the SNR is referenced at the input of the non-coherent integrator.
  """
+ if n_nc == 1:
+ return 0.0
+
  sigma2 = 1 # Noise variance (power), sigma^2
  A2 = linear(snr) * sigma2 # Signal power, A^2
 
@@ -176,6 +179,9 @@ def _non_coherent_gain_out(n_nc: float, snr: float, p_fa: float) -> float:
  """
  Solves for the non-coherent gain when the SNR is referenced at the output of the non-coherent integrator.
  """
+ if n_nc == 1:
+ return 0.0
+
  sigma2 = 1 # Noise variance (power), sigma^2
  A2 = linear(snr) * sigma2 # Signal power, A^2