Digital broadcasting denotes a broadcasting system where the broadcasting signal is digitalized. The digital signal at the end users’ site can be fed directly into the integrated digital receivers, or in a transition period, e.g. regarding TV, through a set-top-box to a regular analogue TV receiver.
Digital broadcast denotes a set of standards that aim to distribute broadcast signals in digital form in a specific and standardized way. In this set of standards room is also created for the transmission of data services. Data services in Digital broadcast standards are either stand-alone data services or program related data. Digital broadcast standards are not worldwide standards and different markets apply to different standards: European DAB &DVB, US ATSC or Japanese ISDB standards. The main block of the Digital TV standards, namely video compression standard MPEG-2, is deployed in the majority of standards.
Because of specific characteristics of different infrastructures, different standards apply to different infrastructures. In the European DVB standard, different sets of standards are developed for all current infrastructures (Cable, Satellite and terrestrial). DVB standards are widely used all over the world in terrestrial, cable and satellite digital TV. In some markets, combinations of different standards are also used.
For analogue broadcasting each TV program requires its own set of frequencies. A transmitter distributes the program and as a transmitter; for example, terrestrial broadcasting has a limited coverage area countrywide, and regional distribution requires the deployment of several bigger and smaller transmitters. The different transmitters must use different frequencies to avoid noise or disturbance. The result is that a set of frequencies is necessary to cover a country with one TV program.
For users, digital broadcast will offer many advantages over analogue broadcasting, such as better technical quality, more programs and services on a given set of frequencies, and the option of multimedia and interactive services. This development is an expression of converging media: digital broadcast platforms will integrate elements from several different media, computers, telecommunications and broadcasting. The shift to digital broadcasting is not simple, however, as it introduces a range of interrelated political, economic and technical challenges. Some of these challenges are specific to the mode of distribution: satellite, cable or terrestrial, with the latter having special problems and potentials.
The services that will be feasible in the digital broadcasting networks will go beyond traditional TV and radio and encompass a range of new services like:
- Enhanced text TV. By using graphical tools, hypertext etc. the text TV in digital version can be more advanced and usable.
- Download of software. The broadcasting networks are mostly used in the day and evening hours. The transmission capacity at night can be used to download, for example, new versions of software to the set-top-boxes.
- Download of newspapers. In the same way newspapers can be downloaded to the set-top-boxes.
- E-commerce. The products can be ordered by remote control, e.g. during advertisement.
- Internet on TV. Access to the Internet as known in the communication networks will not be possible because of capacity-per-user problems of digital TV networks. Here the solution can be to broadcast a limited version of Internet, e.g. sites that are seen relevant from a political/societal perspective.
As seen, there are a number of possibilities to utilize the potentials of digital broadcast networks to offer data service and therefore to use it as a tool to reduce the digital divide.
As the basic technologies are now ready, solutions to two sets of regulatory issues are pertinent for the development and diffusion of terrestrial DVB. One set of issues is related to the concept of Public Service Broadcasters. In almost all countries, cultural policy considerations have given rise to privileges and obligations for a few broadcasters. There is general acceptance of the need for the continued existence of Public Service Broadcasters, but to what extent are they needed in the context of new services? There are some parallels to be drawn in the discussion of Universal Service in telecommunications, but the emphasis on content in broadcast regulation adds new dimensions to the discussion. These regulatory problems are, however, not the focus for this paper.
The other set of regulatory issues is related to new facilities such as multiplexing (management of frequency sharing), Electronic Programming Guide (EPG), and Conditional Access (CA). The organization of the multiplexing function becomes crucial, as digital broadcasting allows a number of content providers to share frequencies traditionally allocated to one channel. The EPG represents users' entrance to the digital services. Especially for small language areas, the strong presence of national programs makes cultural policy and some regulation a high priority in relation to these functions. Conditional Access regulates entry to services typically via an entrance code on a PCMIA-card. From a user’s perspective, it is essential that entry control is standardized and does not require different hardware for each content provider.