Satellite data narrowcasting-system investigations

Satellite narrowcasting based on the use of spare capacity on FM TV signals allows low cost data broadcasting to closed user groups because the receive dish required is relatively small and domestic VLSI chips can be used. Satellite transmission allows data, which can represent computer files, facsimile pictures, high resolution still colour pictures or even low bit rate moving pictures to be transmitted to a much wider coverage area than economically possible with current terrestrial data broadcasting systems. The data capacity available is also significantly greater. In the short term, it is expected that such systems will be mainly used for electronic messaging and facsimile transmission to small business premises. In the future, it will be possible to transmit data for any of these applications and many others, direct to the home. The author discusses the hardware and software which is being developed to implement a practical data narrowcasting system for satellite trials. The results of transmission tests using the PAL/VBI and MAC/packet options are then presented and the implications for system and receiver design discussed