TONKANALSCHALTUNG FUER DIGITALE FERNSEHEMPFAENGER.

摘要

The audio circuit has the analogue video/audio signal mixture (va) fed to an A/D converter (ad) via an analogue anti-aliasing low-pass filter (af). The video signal is extracted from the output of the A/D converter (ad) via a filter structure (bp, dz, tp). The digital audio signal (ds) is fed to a phase splitter (ps) with a 0 degree output (aO) and a 90 degree output (a9) fed to a phase discriminator (pd). The latter provides as audio signal with a demodulated amplitude. The phase output (ap) of the phase discriminator (pd) supplies the DQPSK partial decoder of the 'NICAM' decorder (nd) and provides the frequency-modulated audio signal via a differentiation stage (dt).