TV is on the move
Television, the Internet, and other broadcast video-based services may soon be available in cars and on public transport. This has not been possible until now, as standard analogue broadcast signals cannot be successfully received when the receiver is moving. Advances in digital terrestrial broadcasting may hold the answer. Background In today's fast-moving world, there is an increasing demand for broadcast services that can be received in mobile environments such as cars and public transport. A prime example of this trend is the explosion in the use of mobile phones - today, more than 300 million users are already connected to cellular telephone networks. Digital terrestrial broadcasting could soon fulfil demands for reception of more extensive data services - such as TV channels or the Internet - in these moving environments. The broadcasts must be digital, as traditional analogue signals do not allow mobile reception. First, though, there must be agreed broadcasting standards: DVB-T is the only internationally approved standard for digital terrestrial television broadcasting in Europe, and is the only system which will be adopted in the 15 EU Member States. In May 1998, a consortium of 17 companies and organisations, led by T-NOVA (formerly Deutsche Telekom BERKOM), launched the Motivate project, funded by the European Commission under the ACTS (Advanced Communications Technologies and Services) programme. The aims of the Motivate team were to investigate the theoretical and practical performance limits of DVB-T for mobile reception. Among other areas, the team has worked on the optimisation of receiver algorithms for channel estimation, channel correction and time synchronisation, which will lead to the next generation of DVB-T receivers designed for the mobile environment. Further, it has prepared guidelines for broadcasters and network operators on how to implement DVB-T networks for mobile receivers. Description, impact and results Motivate workers have performed three laboratory test campaigns, the first in November 98 in Darmstadt, the second in October 99 in Berlin, and the third in December 1999 in Stockholm. Some eight receivers were assessed in a test-bed environment. These were effectively three design generations: the earliest generation used discrete components, the second included a `first generation' chip set, and the third was designed with a `second generation' chip set. They were selected to cover three application domains - consumer equipment, professional equipment and experimental receivers - some of which use `antenna diversity' systems, where multiple, separated aerials are used to improve reception quality. Indeed, it is the progress made in the development of antenna diversity systems that the team quotes as one of its major achievements. Field trials complemented the laboratory work. As an example, there was a demonstration of mobile DVB-T capability during the IST (Information Society Technology) conference in Helsinki, in November 1999. City trams were fitted with innovative TV sets receiving a 30-minute `show', which clearly showed the technical viability of mobile DVB-T reception. Working partnerships The Motivate team included members with expertise from all possible areas: broadcasters, network operators, manufacturers of professional and domestic equipment, and research centres. The tram demonstration was set up using plasma flat screen TV receivers from Nokia, and the digital TV signals were broadcast by Digita - a subsidiary of Yleisradio (the Finnish Broadcasting Company) - which is responsible for the Finnish national transmission and broadcasting networks. In addition, the project had the backing of sponsoring partners such as BMW, NDS, RTE and Siemens.