JPL's Wireless Communication Reference Website

Chapter: Network Concepts and Standards
Section: Broadcast Systems


Digital Video Broadcasting

Television broadcasting is nowadays rapidly progressing towards the digital era. Soon, transmission of television signals will be done in a fully digital format, using audio and video compression techniques (MPEG-2) that make use of the frequency spectrum in a far more efficient manner than the analog techniques currently in use. As a direct result, the costs for using a transponder (per service) will drop, new broadcasters are likely to emerge quickly and the number of services offered to the consumer will explode. Some television marketing concepts rely on Pay TV: it is expected that the audience will choose for higher quality channels that offer services better suited to their needs, and also that the audience is willing to pay extra for these services.

Standardisation of digital television systems is formally discussed in the European Digital Video Broadcasting (DVB) Project. Many different transmission media are considered, including

The DVB Project is an ensemble of committees formed by representatives of network providers, satellite operators, broadcasting, telecommunications and manufacturing companies from all over Europe.

The aim of the DVB Project is to arrive at standards on transmission of digital video data through the air (terrestrial), through cable and by satellite. Issues on the table are for instance modulation and channel coding, service information, multiplexing and also conditional access. The ultimate goal is to create a business environment where consumers are reasonably well protected and where various providers of services and equipment can compete on fair terms and where new businesses can enter without excessive thresholds.

The DVB Project started in 1991, when a so called Technical Module was established. Since then, the Project has steadily grown in size; over 150 companies that wish to participate in the discussions have today signed the Memorandum Of Understanding.

In the DVB Project, two groups focus on scrambling and conditional access. Both groups study the feasibility of a scheme where the systems share as much commonality as possible. The first, a commercially driven group called the Ad-Hoc Group on Conditional Access (Ad-Hoc group on CA), considers complete conditional access systems, including scramblers/descramblers and peripheral equipment at the transmission side. The second group, concerned with the more technical issues and called the Conditional Access Specialist Group (CASG), focusses on the decoder box and transcoding issues.

Example of digital TV system

Source of these images: Philips, Digital Video Systems (DVS), Eindhoven



JPL's Wireless Communication Reference Website Daan van Schooneveld and 1993, 1995, 1996.