Barracuda Networks SP4 Instrukcja Użytkownika Pobierz pdf (Strona 52)

STEREO GENERATOR – INPUT CHANGEOVER

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23 STEREO GENERATOR – INPUT CHANGEOVER

23.1 THE MPX SPECTRUM

We assume MPX signal is composed by three major components:

• Audio Signal (L and R channels)

• Stereo Pilot tone (19Khz)

• Radio Data System signal (57Khz)

The stereo encoding process modulates (double side-band suppressed carrier) the L-R or stereo difference signal onto a

38kHz sub carrier. Its side-bands will extend by +/- 15kHz. At the top end this will be 53kHz. Digital filter accomplishes all

contents above 53 kHz are suppressed by the highest level. This precise spectral management contributes to loudness,

since it ensures that no wasted energy is transmitted.

Please note that composite clipper does not degrade RDS signal quality because it is applied before the 19kHz pilot is

added to the multiplex signal (if the pilot was present at the composite clipping stage, the third harmonic of the pilot

caused by the clipping process will fall exactly on 57kHz, degrading the RDS).

Each component of MPX signal is generated digitally and therefore available at the highest quality.

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Barracuda Networks SP4 Instrukcja Użytkownika Strona 52