By Ned Mountain, Wegener Communications, Inc.
Over the past four years, extensive operational experience has been gained with multiple subcarrier technology. Driven by marketplace demands for low cost audio and data distribution capabilities, the development of the techniques of multiple subcarrier operation has reached a refined level. To date, over 100 channels on 40 transponders on eight different satellies are utilizing technology developing by Wegener Communications.
This paper will discuss in detail the technical principles behind multiple subcarrier operations. Areas that are of primary interest are composite deviation, modulation waveforms, occupied bandwidth and video degradation. Discussion of experiences with U.S. NTSC, European PAL and Intelsat half-transponder NTSC will be presented to illustrate the major points.
Application of multiple subcarrier technology will be detailed including audio channels of various bandwidths and data channels of various data rates. A detailed and flexible baseband plan is imperative to enable maximum transponder utilization. Examples of such plans will be presented.
The overall objective of this paper is to provide a clear understanding of transponder operation with multiple subcarriers and suggest ways in which the technologies can be put to use solving today's problems.