Application of Delta-Modulation to Television Systems

Abstract

Digital methods of pulse modulation are being widely applied in the transmission of information over communication networks. The thesis is primarily concerned with one specific class of pulse modulation called delta-modulation. In its basic form, delta-modulation represents the simplest and most economical method of digitally encoding analogue signals. The thesis discusses delta-modulation from a theoretical and practical viewpoint. A mathematical model is presented which permits a comprehensive understanding of the processes of delta-modulation. The model can readily be extended to other forms of digital pulse modulation and is therefore presented as a general method of analysing digital-encoding systems. The theory develops the design requirements of a delta-modulator and indicates methods of improving the encoding performance. The thesis describes a family of digital encoding systems for colour television. These systems are discussed in relation to chromaticity. Finally, a particular system is described, for which an experimental model was built and tested. This system transmitted the chrominance information during the line blanking period. The experimental model functioned satisfactorily in real time with encoding rates ranging, from 50 Mhz to 190 Mhz. At these pulse rates, subjective assessment of the system was favourable.