comnum.snr_m2m4_db#

comnum.snr_m2m4_db(x, constellation)#

The M2M4 estimate of the SNR (Pauluzzi & Beaulieu 2000), generalised to alphabets of several amplitudes by their kurtosis; it degrades at high SNR for QAM.

Parameters:

  • x (array_like) – the samples (complex), at one sample per symbol.

  • constellation (Constellation) – the alphabet.

Returns:

the SNR (dB); inf when the moments give no noise.

Return type:

float

Raises:

ValueError – for an invalid parameter or input (the message names it).

Examples

>>> import comnum
>>> rng = comnum.Rng(2)
>>> c = comnum.Constellation("psk", 8).normalized()
>>> x = c.points[rng.integers(8, 100_000)] + rng.complex_noise(100_000, 0.1)
>>> round(comnum.snr_m2m4_db(x, c), 1)
10.0