Digital TV Broadcasting

European perspectives in digital television broadcasting – Conclusions of the Working Group on Digital Television
U. Reimers (97 KB)

In Europe, a coordinated activity was started in early 1992, which aims at the design of a common system for digital television broadcasting. Under the auspices of a European Launching Group composed of members of eight countries representing a range of organizations involved in the business of television, the Working Group for Digital Television Broadcasting (WGDTB) has defined system approaches for such a digital service.

The findings of the WGDTB are reported and the three systems proposed for study and future implementation are presented. All three are multi-layer systems, which include two or more service levels which are inter-related either in a hierarchical or in a multicast mode.

European perspectives in digital television broadcasting – Quality objectives and prospects for commonality
D. Wood (44 KB)

In Europe, a series of collaborative projects are developing elements of digital terrestrial and satellite broadcasting systems. Efforts are being made to encourage these projects to work towards a common standard for Europe.

The article outlines some of the proposals already made for an initial target system. Particular explanations are given of the current quality goals, and how they were established.

Other issues considered are coverage problems, commonality of terrestrial with satellite, common multiplexing, and conditional access.

HD-DIVINE, a Scandinavian terrestrial HDTV system
P. Appelquist (57 KB)

In the summer of 1992 a digital terrestrial HDTV broadcasting system was demonstrated as a result of a collaborative Scandinavian study. The system included a motion compensated hybrid DCT video codec, a 512-carrier OFDM 16 QAM modem and four ISO/IEC Layer II sound codecs. The complete system was implemented in hardware. Since then further refinements of the vision codec and final assembly of the modem have resulted in a fully operational demonstration system and in January field trials have started. The current implementation uses the 1250/50/2:1 studio standard and fills an 8 MHz UHF channel. A second implementation, ready in March 1993, will allow reconfiguration from 1 HDTV input signal to 4 input signals conforming to CCIR Recommendation 601.

European activities on digital television broadcasting – From company to co-operative projects
B. Marti, N. Lodge, P. Bernard and R. Schäfer (88 KB)

This contribution focusses mainly on the channel aspects of some European digital television projects, the source coding aspects being dealt with mainly in the framework of a larger standardization effort within MPEG.

The channel-related studies in Europe take account of a particularly difficult situation as regards frequency planning, and are aiming at single frequency networking as a means of achieving maximum economy of frequencies. Continuing the approach adopted for Digital Audio Broadcasting, COFDM is the favoured system Europe and is the basis of the digital terrestrial television broadcasting (dTTb) project funded by the European Commission.

The first results are very encouraging, although the feasibility of portable reception – a specific feature of terrestrial broadcasting that cable and satellite systems cannot offer – remains to be fully established.

Digital multi-programme TV/HDTV by satellite
M. Cominetti, A. Morello and M. Visintin (276 KB)

The progress of digital technology since the WARC'77 is considered and the perspectives of future applications via satellite channels are identified. Among these, digital multi-programme television systems, with different quality levels (EDTV, SDTV) and possible evolution to HDTV, are evaluated in terms of picture quality and service availability on the satellite channels of the BSS bands (12 GHz and 22 GHz) and of the FSS band (11 GHz) in Europe. A usable channel capacity of 45 Mbit/s is assumed, as well as the adoption of advanced channel coding techniques with QPSK and 8PSK modulations. For high and medium-power satellites, in operation or planned, the receiving antenna diameters required for correct reception are reported. High-level modulations (16QAM, 32QAM, 64QAM) are considered for distribution of the satellite signal in cable networks.

Digital broadcasting of studio-quality HDTV by satellite in the 21-GHz frequency range and by coxial cable networks
C. Dosch (167 KB)

Backed up by extensive research and demonstrations, the frequency band 21.4 - 22 GHz was finally allocated to the broadcasting satellite service by WARC-92. The band is intended to be used for near studio-quality digital HDTV with associated multi-channel surround sound.

Digital transmission can cope with the propagation conditions in this band, which are more difficult than those encountered in the 11 or 12 GHz downlink bands, and allows more flexibility for frequency planning than analogue schemes.

In cable networks, digital multi-level modulation permits the use of relatively narrow-band transmission channels.

The article gives an overview of the current state of development.

Tutorial

Principles of operation of video encoders and decoders in the production domain EBU Sub-group G4 (83 KB)

This EBU TUTORIAL has been prepared within the framework of an Ad-hoc Group of EBU Sub-group G4 (Video origination equipment). It deals with the basics of conventional PAL and SECAM encoding and decoding equipment which is now widespread in EBU Members' production facilities.