The design of the downlink in a DBS system requires optimization of a set of complex interrelated objectives. This paper describes the objectives, demonstrates the interrelationships, and discusses the process of selecting system design parameters to best balance the objectives of the DBS business entity. The Satellite Television Corporation's (STC's) system design is presented as a case study. Performance requirements are stated in terms of consumer perceived picture quality and rain-fade protection. The requirements are generated by a subjective testing program. The system objectives are formulated consistent with performance requirements, competitive products, and economic reality. To meet the objectives, four major design parameters can be adjusted: satellite power, satellite antenna beam shape, home equipment performance, and signal format characteristics. This paper deals with the first three of these parameters. The manipulation of these parameters to meet system objectives is illustrated by the STC case study. It is demonstrated, for this sample system, that the choice of design parameters varies across the targeted service area, depending on demographics, competition, consumer expectations, weather, and other factors. However, in general, the STC design provides antenna sizes of 0.6-0.75 m for 92 percent of TV households, extremely high clear-sky picture ratings, and a sufficient rain-fade margin to provide acceptable levels of service outage.

For almost all viewers, today's television is perfectly acceptable when displayed on a 19 in or smaller set. However, for larger sets (e.g., 5 ft diagonal), many viewers object to the lack of sharpness and the visibility of the scanning lines. High-definition television (HDTV) can provide sharp images on larger sets and eliminate the line-visibility problem. Moreover, the HDTV picture will have a wider aspect ratio (i.e., width-to-height ratio), thereby occupying more of the viewer's field of view or peripheral vision. The combination of sharp images and wide visual field provides a medium with the impact and realism that can now be found only in the cinema. For the millions of viewers who prefer the larger pictures (roughly a half million projection TV sets are sold every year), HDTV would be an attractive new service. However, HDTV may require a considerable financial investment in DBS satellites, a disadvantage for a new (read: untried) service which is expected to grow at a modest pace since each HDTV subscriber would have to buy a new HDTV set. This paper examines home HDTV from the perspective of a DBS operator, including visual requirements and several suggested HDTV systems.

The World Administrative Radio Conference, Geneva, Switzerland, 1979 (WARC-79) decided many of the international issues facing the Broadcasting-Satellite service (BSS) and adopted Resolutions and Recommendations dealing with most of the others. This paper identifies the BSS issues considered at WARC-79, describes the actions taken during the Conference, indicates the current status of subsequent WARC-mandated activities involving the BSS, and assesses the potential impact of the WARC on future BSS systems.