No. 297 (January 2004)
Forecast 2003 – held on 4 and 5 November – is the annual specialised meeting of the EBU’s Broadcast Management Committee (BMC). This year's programme was put together by four members of the BMC – Etienne Deventer (VRT Belgium), Pierre Kasser (TDF France), Nigel Laflin (BBC UK) and Chris Weck (IRT Germany), who also acted as session chairmen. The programme consisted of interesting presentations that covered results from some of the BMC project groups as well as developments in the ITU and the broadcast industry.
Some of the highlights of the presentations at Forecast 2003 are described here.
World Radiocommunication Conferences (WRCs) are organized by the ITU every 3 to 4 years, to update the allocation and use of the radio-frequency spectrum in view of new developments.
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On 9 July 2003, WRC-03 opened in Geneva with more than 2,500 delegates attending the four week-long session. Terry O’Leary of the EBU Technical Department explained that broadcasting interests at WRC-03 could be split, on the one hand, into protection of broadcasting bands and, on the other hand, on achieving additional broadcasting allocations. |
A major achievement is that shortwave broadcasting bands can be used for digital broadcasting (DRM). However, extensions of the shortwave broadcasting bands have not been realised and the matter has been postponed to WRC-07. Many items that could potentially restrict broadcasting have either been rejected or postponed. Of particular interest in this respect is the consideration of an allocation to mobile services in the frequency range 806 - 862 MHz (TV channels 63 to 69) following the transition from analogue to digital – indicated on the provisional agenda for a WRC in 2010.
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Other types of ITU conference are Regional or World Conferences for agreeing detailed frequency plans. The ITU conference for the planning of digital broadcasting in Europe, Africa and the Middle East – RRC-04/05 – is perhaps the most important event in broadcasting in the next few years. |
Phil Laven, director of the EBU Technical Department, drew attention to the EBU Guidelines for RRC-04/05 [1]. These guidelines are in the form of answers to questions raised in the EBU Technical Committee.
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BPN 003 |
Preparation for RRC-04/05 takes place in several BMC project groups and many contributions have been made to CEPT and the ITU. Also, reports in the EBU-BPN series have been produced as guidance in frequency planning. The report of ITU Task Group 6/8, which provides a good basis for the first session of the conference, was presented by Stanko Perpar (RTVSLO), who was chairman of that group. Ken Hunt from the EBU Technical Department showed different ways for planning digital services and the options for taking into account (or not) analogue TV. It was pointed out that an overall analysis of the plan, made several times during the planning process, is needed. The outcome of such an analysis may be different than expected and may be difficult to present and understand. |
Roland Brugger (IRT) showed the aspects of allotment and assignment planning. An allotment gives the right to use a frequency in a described area, respecting the outgoing interference limits associated to that allotment. Allotment planning gives more flexibility in future when transmitter networks may need to be changed in order to improve coverage for indoor, mobile or handheld reception. Peter Rogers (RTE), chairman of EBU Project Group B/CP-R showed the complexity of planning digital broadcasting in Band III. Not only two digital systems, T-DAB and DVB-T, need to be planned but also there are countries with 7 and 8 MHz channel bandwidth and different channelling schemes.
Recently, the European Commission started activities regarding spectrum management. Two committees have been set up by the EC: the Radio Spectrum Policy Group (RSPG) to provide policy and strategic advice and the Radio Spectrum Committee (RSC) for adoption of technical measures that are necessary to implement agreed EU policies. One of the subjects of the RSPC is a study on the frequency-spectrum implications of the switchover to digital broadcasting. Percy Pettersson (Teracom), chairman of Project Group B/SMI indicated that spectrum trading is another study initiated by of the RSPG. The value of the spectrum has also been the subject of studies in the EBU. Bands III and IV/V, along with the GSM and UMTS bands, can be marked as having high value, whereas microwave bands, Band I and ISM bands can be marked as low value bands. EBU Members already pay a lot for the spectrum they use, and spend high additional amounts to implement more spectrum-efficient digital systems. However, the universal coverage obligation means that EBU Members need more spectrum to provide a service than commercial broadcasters that are only interested in covering urban areas.
In the UK, DVB-T services are planned for rooftop reception. Ian Adams of the BBC reported on the very successful introduction of “Freeview”, the free offer of 30+ digital terrestrial TV channels. A year after its launch in October 2002, 2 million households enjoy DVB-T reception, making digital TV receivers the best sold electronic consumer product in the UK.
Digital broadcast systems (DVB-T and T-DAB) enable good indoor, outdoor and mobile reception to be achieved. However, a higher field strength is needed compared to roof-top reception, to compensate for the low antenna gain, lower receiving height and building penetration loss.
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Chris Weck (IRT) showed the results of indoor reception measurements in Berlin and confirmed the building penetration loss values given in ITU and EBU reports, as well as in the Chester agreement. A polarization loss of 6 to 7 dB was assessed in cases there the transmitter and portable receiving antennas were orthogonally polarized. |
With diversity reception, mobile and indoor reception can be improved. In this technique, more than one receiving antenna is used. Yannic Levy of DiBcomm presented practical results obtained by diversity reception. It was concluded that the C/N value for mobile reception was 5 to 7 dB lower compared to a single antenna and the Doppler frequency increased by about a factor of 2. For portable reception, the C/N improvement is even higher. However, diversity reception adds to the cost of the receiving equipment.
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The T-DAB plan of Wiesbaden ‘95 is based on mobile reception. Today, portable and handheld receivers are also entering the market. It thus becomes more important to make the DAB networks suitable for indoor reception either by increasing the transmitter power or by adding more transmitters. |
Simon Mason of NTL reported on the building penetration loss measurements made in central London. A building penetration loss of 15 dB was found, with a standard deviation of 5dB. It is unlikely that transmitter powers can be increased considerably, due to international frequency coordination limitations. Therefore, more low-power transmitters in the DAB Single Frequency Networks need to be installed in order to improve indoor reception. To avoid interference to first and second adjacent channel reception, high transmitter powers should also be avoided.
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Large Plasma Discharge Panels (PDPs) are becoming popular and prices have come down to almost 3000 euros. However PDPs suffer from burn-in. Mike Croll (BBC), chairman of Project Group B/TQE, stated that LCD panels are expected to dominate the large-screen market in 4 years. LCD panels do not suffer burn-in and can be made with high-definition resolution at any size. |
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Small LCD screens offer opportunities for broadcasting in combination with other services to mobile phones or Personal Digital Assistants (PDAs). Pekka Talmola (Nokia) showed Nokia’s handheld mobile phone with TV reception capabilities. |
Implementation of these kind of devices has some impact on frequency planning. Due to the small antenna dimensions, a relatively high field strength is required for good reception and, if combination with GSM900 is required, the upper TV channel to be used is 49 in order to guarantee a sufficient frequency separation.
Another aspect regarding screen size is the compression method used. DVB-T uses MPEG-2 but, in the case of IP datacasting or in future for HDTV, other compression methods could be used that are more adapted to either small or large screens. Project Group B/VIM has done many tests with video compression methods. The results of these tests were presented by Franc Kozamernik of the EBU Technical Department. A bitrate of about 250 kbit/s offers good picture quality at very small screen sizes (QCIF) with recently-developed compression systems. Good pictures at normal screen sizes (SDTV) could be realised with 70% to 50% of the bitrate needed for MPEG-2. This is promising for HDTV that would otherwise require bitrates of up to 19 Mbit/s. However the licensing terms of some of these new compression systems could be unfavourable, and broadcasters could even decide not to use particular systems for that reason [2].
Interactive services will enable the consumer to access “cooperative content” – material that supports the main programme. Gerhard Stoll (IRT), showed that cooperative content can be presented on the TV screen, or alternatively on separate devices such as a PDA connected to a home server by Wireless LAN. In the latter case, the main programme continues unobstructed on the main screen.
The Personnel Video Recorder (PVR) will provide a virtual on-demand service by storing content taken from a broadcast channel. Paul Gardener (ITC), chairman of Project Group B/ITVA, emphasized that these devices will be on sale soon. In order to make full use of the possibilities of PVRs, in free-to-air broadcasting within horizontal markets, the essential and desirable features need to be identified and supported by EBU Members before launching a DVB-T service.
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In order to let interactivity happen, the receiver or set-top box should be equipped with an API. The EBU recommends the DVB-MHP as the preferred API for new digital TV platforms. |
Alexander Erk (IRT) indicated a number of receivers equipped with MHP and a number of on-air MHP applications, and presented results of MHP compliance tests. Nicola Frank of the EBU’s Brussels office explained that the European Commission does not mandate MHP, but Member States of the EU are encouraged to use open APIs.
Digital radio has been implemented in many European countries and many types of DAB receivers, within a broad price range, are now available. DRM is another system for digital radio. Peter Senger of Deutsche Welle and chairman of the DRM consortium reported that DRM had been launched officially in June 2003 during WRC-03. In October 2003, there were 354 hours per day of DRM transmissions, with near-FM quality, from 41 transmitting stations.
DRM is not seen as a competitor to DAB. Agreements with industry have been reached for combined DAB-DRM receivers. DRM is intended for international broadcasting in the shortwave bands, but can also provide national or regional services in the LF and MF bands. Some organizations are even experimenting with local DRM services in the 26 MHz band.
Internet Protocol (IP) is a way to deliver data over various kinds of networks without protocol conversion. Francesca Mari (e.BisMedia) showed the possibilities of TV over ADSL and optical fibre. For instance, RAI in Italy offers on-demand channels and also its regular TV services in this way. Ralf Schäfer from Thomson presented the home network of the future where broadcast content either via broadband or broadcast channels will be received on a server and distributed in the home via either wired networks or high capacity Wireless LANs, while all terminals will be equipped with MHP.
Vesa Erkkila (Digita) explained that DVB-T networks could also be used for providing data services, using IP, to computers – for instance in rural areas or to hand-held devices using the recently specified DVB-H system.
Today, the BMC is dealing with more than just broadcasting in the traditional sense. Interactivity, multimedia, multiplatform and high-quality are key words in addition to broadcasting and this has been reflected in the programme of Forecast 2003.
“There
has never been — nor should we try to make — a
single definition of
Public Service Broadcasting in Europe.
(it is for the nation and the PSB themselves to do so)”
These words come from the report of the EBUs Digital Strategy Group “Media with a purpose – public service broadcasting in the digital era”. Therefore, individual EBU Members may have different views of the relative importance of the issues presented at Forecast 2003 and on the choices that need to be made sooner or later on the “road map for broadcast technology” [3].
References
[1] EBU Technical Document I37-2003: EBU Guidelines for RRC-04/05
[2] EBU Technical Statement-D 96-2003: Joint H.264/MPEG-4 AVC patent licence
[3] J. Doeven: A road map for broadcast technology, EBU Technical Review, April 2003
Jan Doeven
Chairman, EBU Broadcast Management Committee
| European Broadcasting Union L'Ancienne Route 17A CH-1218 Grand-Saconnex Geneva Switzerland techreview@ebu.ch |
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