Modulation of conventional TV signals in all-digital CATV network head ends

In this paper, a new digital intermediate frequency modulator for conventio nal TV signals using digital signal processing is presented, A composite co lour video signal and two associated audio signals are converted into a dig ital composite TV signal with spectrum at intermediate frequency. The modul ator is designed for the high quality requirements that exist in profession al equipment for CATV head ends. The architecture of the digital modulator shown is optimized for an implementation with ASICs. The signal processing with reduced complexity is described in detail, the structures and the desi gn of the filters are illustrated and the simulated results are presented.