Transportable satellite up-links towards SNG?

The possibility that satellites could be used for occasional outside-broadcast (OB) links has interested broadcasters for many years. It is only within about the last five years that practical experiments have been possible, but it is clear that highly mobile satellite news gathering (SNG) links are now becoming available. Most of the early satellites used the 6 and 4 GHz frequency bands on relatively insensitive satellites, and the ground station aerial needed was a fairly massive structure not amenable to rapid deployment. Nevertheless, certain occasions were sufficiently demanding to justify the use of demountable stations. Provided that there was enough time available, these stations represented a practical way to provide connections for major events on which fairly high costs could be justified. The 6 and 4 GHz frequency bands are both used intensively for terrestrial links, and the frequency co-ordination process involved in placing a satellite up-link to avoid interference limited this type of operation to events planned several weeks in advance. With the availability of domestic and regional satellites using the 14 and 11 GHz bands, it became possible to use an aerial size much more suited for rapid transport. Furthermore, the 14 GHz band is used very little for terrestrial links, and the co-ordination problem is amenable to a much more rapid analysis. The combination of these aspects has made it possible to move towards the era when not only special preplanned events can be linked by satellite but it becomes possible to consider rapid coverage of news events arising without prior notice. Several transportable terminals have now been built, and the features of one of these designs are described, especially related to the operational requirements. Sufficient studies have now been carried out to suggest that the potential problem of interference to adjacent satellites can be overcome and the extent of the consequent design constraints are examined. The Europe- n Broadcasting Union (EBU) has decided to rent two full-time transponders in the future ECS satellite to supplement its terrestrial Eurovision network. A common specification for SNG terminals to be used with the system has been suggested, and this is included in the paper for reference.