A New Modulation Concept for Mixed Pseudo Analogue-Digital Speech and Audio Transmissioin

Current speech, audio, and video coding and transmission systems are either analogue or digital, with a strong shift from analogue systems to digital systems during the last decades. We have combined both digital and analogue schemes for the benefit of saving transmission bandwidth, complexity, and of improving the achievable quality at any given signal-to-noise ratio on the channel. The combination is achieved by transmitting pseudo analogue samples of the unquantized residual signal of a linear predictive digital filter which is called mixed pseudo analogue-digital (MAD) transmission. In this paper a new modulation scheme based on QPSK for digital information and an Archimedes spiral for the time discrete, pseudo analogue residual signal is introduced and evaluated.