comnum.fm_stereo_decode#

comnum.fm_stereo_decode(mpx, fs, *, tau_s=5e-05, fs_audio=48000.0)#

The left and right channels of a multiplex (ITU-R BS.450-4 Sec. 2.2): the pilot found by mixing it down (10 ms average), S = LP{2 m sin 2θ} and M = LP{m} at 15 kHz, A = M + S, B = M - S, de-emphasised and resampled to fs_audio; mono (A = B = M) when the pilot deviates by less than 2 kHz.

Parameters:

  • mpx (array_like) – the multiplex in hertz of deviation (fm_discriminator()).

  • fs (float) – its sampling rate (Hz), at least 120 kHz.

  • tau_s (float) – the time constant of the de-emphasis (s).

  • fs_audio (float) – the rate of the audio (Hz), at least 30 kHz.

Returns:

left, right (float64, full scale 1), fs (Hz), pilot_hz (the deviation of the pilot), stereo (bool).

Return type:

dict

Raises:

ValueError – for invalid rates.