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Verification And Launch of Integrated Digital Advanced Television in Europe

Résultats exploitables

Summary : VALIDATE Partners carried out a wide range of tests in standardized conditions in the laboratory and extensive field trials in about a dozen areas in seven different countries. A substantial document (about 120 pages) bringing together all the Project's results relevant to service planning was submitted to CEPT PT 24 as part of the preparation of the Chester conference on coordination of digital terrestrial television transmitter assignments. The availability of these results was a critical factor in achieving agreement at the Conference. The Conference output document lists parameters to be used for international coordination that are based on the VALIDATE results.
Summary : Setting up digital terrestrial TV broadcasting networks will require agreement between transmitter manufacturers and transmission network operators and between the network operators and the service providers on the specifications for the performance of transmitters, including functional blocks and the interfaces between them. As this is a new technology, there is no existing basis for such specifications. VALIDATE has therefore drawn up a transmitter performance specification and submitted it to DVB. The aim of this document is to suggest the parameters that need to be measured and some realistic values for them as well as to define the minimum interface specifications (not all of which are mandatory).
Summary : VALIDATE participants amassed a great deal of experience in all aspects of the implementation of DVB-T services. To make this experience available to broadcasters not involved in the project, they prepared Implementation Guidelines aimed at the technical staff of other broadcasters. These guidelines were distributed via the DVB Project, and are publicly available as an ETSI Technical Report.
Summary : A digital multimedia database of 295 talking faces has been recorded. In terms of the number of subjects and its multimodal (video, 3D, speech) content the database is unique and will facilitate continuing research in the area of personal identity verification by the partners and the extramural research community. The speakers utter predefined sentences (sequences of digits and a phonetically balanced sentence). Subsequently, they perform a lateral and vertical head rotation. The subjects were recorded on four different occasions over a period of four months.
Summary : Two approaches are possible to the planning of DVB-T networks: multi-frequency networks (MFNs) and single frequency networks (SFNs). MFNs are planned in the same way as analogue networks, using an individual set of radio frequencies for each transmitter. This approach might be considered when an Administration wishes to re-use some or all of the spectrum used for analogue broadcasting. SFN planning relies on the relative insensitivity of COFDM to delayed signals arriving within the guard interval. It is possible, if a suitable frequency is available and a sufficiently long guard interval is chosen, for all transmitters in a region, or in a country, to use the same frequency, which has the clear advantage of economizing on the frequency spectrum. VALIDATE partners defined a method for synchronizing all the transmitters in an SFN, and this new system was widely tested during the lifetime of the Project. The specification defined by VALIDATE has been published by ETSI as a Technical Report, and some VALIDATE partners have implemented SFN functionality in their equipment. Results of multidimensional interoperability tests carried out by VALIDATE in June 1998 and involving SFNs have been published on the Project's website at http://www.bbc.co.uk/validate/
VALIDATE completed its work in November 1998. It implemented the European specification for digital terrestrial television broadcasting (DTTB) in experimental networks in a number of European countries. It used these experimental networks to verify the specification in detail and to carry out further work needed for the successful launch of terrestrial DTTB services. The first task was to build modems conforming to the specification, or to modify previously designed modems. These modems were tested for interworking to check for ambiguities in the specification. VALIDATE partners carried out laboratory tests and field trials to verify the specification. Besides verifying the specification, the laboratory tests and field trials will also be used to derive the parameters needed for planning DTTB services. These parameters include failure points, susceptibility to interference, and interference caused to other services using the television broadcasting bands (mostly analogue television). Achievements include: comparisons of simulations of a modulator show five laboratories in agreement, confirming that the specification is unambiguous; two modems from different laboratories upgraded to conform with the specification and shown to interwork; first laboratory test and field trial results submitted and specification accepted; first implementation guide completed; primary distribution trials of Moving Picture Expert Group (MPEG)-2 transport streams over dark fibre, synchronous digital hierarchy (SDH), asynchronous transmission mode (ATM), satellite; specification for synchronisation of single-frequency networks (SFN) prepared and accepted; studies of transmitters and sharing with analogue services; first draft specification for transmitter performance; full lab and field test results presented to CEPT Chester 97 conference; study of domestic gap-filler (optimistic results); over-air tests in UK, Netherlands, Italy, Germany, France, Denmark, Eire; demonstrations at International Broadcasting Convention and Montreux, final interworking trials with seven modulators including industrial products and nine demodulators including first-generation consumer chip sets.