comnum.fm_deemphasis

comnum.fm_deemphasis(x, fs, *, tau_s=5e-05)

The de-emphasis 1/(1 + j2πfτ) of the message x by the matched pole y[n] = a y[n-1] + (1 - a) x[n], a = exp(-1/(τ fs)) (ITU-R BS.450-4 Sec. 1.2: 50 µs in Europe, 75 µs in the United States).

Parameters:

• x (array_like) – the real message.

• fs (float) – the sampling rate (Hz).

• tau_s (float) – the time constant (s).

Returns:

the de-emphasised message (float64).

Return type:

numpy.ndarray

Raises:

ValueError – for a time constant or a rate that is not positive.