Television satellite data broadcasting systems and services

Recently, the industry has recognized the importance of television data broadcasting systems for a wide range of services, not limited to stock exchanges. Such services have proved to be essential also for database maintenance, software delivery and/or updating, news broadcasting, and a wide range of other free and payment services, where the same amount of data has to be delivered at the same time to a multitude of users at the lowest price. The expected world-wide expansion of satellite Direct-To-Home digital Video Broadcasting services will allow the transmission of data flows at high speeds (2-34 Mbps/user) without the need for professional end-user's receivers. In fact, as digital video broadcasting will be an open system, most consumer DVB decoders will be able to receive such data, while at the same time req6ired access control will be guaranteed by the embedded encrypting system. This paper traces the current status of data broadcasting technologies in Europe, ranging from slow-rate applications, currently developed on terrestrial TV broadcasting, to the expected broadband services that will be used for multicasting of multimedia services. It will focus on the relative advantages and drawbacks that are peculiar to data broadcasting systems. It will trace the boundary between application fields that could benefit from such systems (e.g. for the implementation of info-highways), especially in countries where people -spread over a large territory- have to be reached while keeping to a minimum the expenses for the setting up of wired infrastructures. The integration of data broadcasting with wired networks in order to provide end users with a return channel is also discussed and some examples are provided.