HDTV and NTSC Transmission Using Direct Digital Synthesis

The technique of direct digital synthesis (DDS) is now available to the commercial marketplace. The DDS technique has several inherent features that render it of particular interest to HDTV transmission systems. Among these features are the following: numeric AM, FM, and/or PM with outstanding linearity; excellent spectral purity; digitally controlled predistortion; single-sideband generation by digital phasing; vestigial sideband generation by digital phasing; easy NTSC-to-HDTV conversion (software); and compatibility with any HDTV format (software). Once the HDTV signal has been digitized, it is fed to a circuit consisting of three integrated circuits (ICs). The output of the digital-to-analog (D/A) converter is the desired radio frequency (RF) waveform between 10 and 20 MHz. This RF signal is then upconverted to the desired TV channel through standard heterodyning techniques.

Print ISSN

0036-1682

Published

1991-12

Content type

Original Research

DOI

10.5594/J02380