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RECEIVING DIGITAL TERRESTRIAL TELEVISION IN THE UK To receive digital terrestrial television in the UK, a viewer needs a Set-top Box (prices start at under £30) or an integrated digital television ( IDTV ). Some set-top boxes are also Personal Video Recorder s, allowing viewers to record programmes from digital terrestrial television onto a Hard Disk . All services apart from the Top Up TV channels and Red Hot TV are available for free to everyone with the ability to receive them (though not all services may be available to those with poor reception). The free channels are generally collectively referred to as Freeview, even though not all of them are technically part of the service. FEATURES Digital terrestrial television provides many more channels than analogue television. For many viewers it offers a higher-quality picture (with many channels broadcasting in 16:9 anamorphic widescreen). A number of interactive services, including a newer version of Teletext , are also offered. An eight-day Electronic Programme Guide (EPG) allows viewers to see the names, descriptions and broadcast times for programmes. As this was not an original feature of digital terrestrial television (it was introduced in 2004), some receivers feature an EPG with details of the current and next programme only. A third-party proprietary 14-day EPG is also provided by a company called 4TV, who formerly carried a 7-day service when only now and next data was normal. This is only available on boxes which support their format and pay a licence fee, generally resulting in more expensive boxes. The service is carried on Multiplex D, meaning that not all viewers can even receive the data. HISTORY Development and launch Digital terrestrial television launched in the UK on of 18 or 24 megabits per second, which can be used for almost any combination of digitally-represented Video , Audio and Data . The DVB-T standard provides a multiplex service that can make trade-offs between the number of services and the picture and audio subjective quality. The Independent Television Commission (ITC) allocated each existing analogue terrestrial channel half the capacity a multiplex each. This meant the BBC got a multiplex to themselves (Multiplex 1), ITV and Channel 4 shared Multiplex 2 (though 10% of the capacity was given to Teletext Limited ) and Five and S4C shared Multiplex A. The remaining space (Muliplexes B, C and D) was then auctioned off. A consortium made up of Granada and Carlton (members of the ITV network, which have now merged to form ITV Plc ) and BSkyB successfully bid for, and set-up, the subscription ONdigital service. The BBC made some use of its multiplex by launching three new television channels, BBC Choice (which had started on 23 September 1998 with four national variations), BBC News 24 and BBC Knowledge ( 1 June 1999 ). ITV used their space to house some of the ONdigital channels (ITV2 from 7 December 1998 ). Channel 4 used their space for ONdigital subscription channels FilmFour and E4. Five sold its half of Multiplex A to S4C (who owned the other half of the multiplex). S4C set up a subsidiary called SDN (S4C Digital Networks) to manage the multiplex and, like Channel 4, rented most of it out to ONdigital. Whilst the BBC was addressing quality of service issues, other broadcasters valued quantity (hence choice) of channels over service reliability and picture quality. {Link without Title} ITV Digital ONdigital suffered from the start and even renaming the service ITV Digital on 11 July 2001 could not save it. and went off-air on 1 May 2002 after the consortium collapsed, giving the reason of overpaying for the television rights for The Football League . However, the choice of 64QAM broadcast mode, 40%+ of aerials needing replacing, a high Churn Rate , awful point of sale marketing, no technical support for customers, an easily Hackable Encryption system, the cost of having to provide set-top boxes for free and aggressive competition from BSkyB brought spiralling costs, not a new "licence to print money" as co-owners Carlton and Granada thought. Freeview As ITV Digital had collapsed, the rights reverted to the regulator and the ITC invited bids for the space on Multiplexes B, C and D. The Freeview consortium (made up of the BBC , transmitter company Crown Castle UK (known from 31 August 2004 as National Grid Wireless , but a privatized BBC engineering division) and BSkyB ) won and launched a new service. Junking the ITV Digital failed business model, Freeview launched on 30 October 2002 with just free television channels, and a wider range of digital radio stations. Top Up TV The space ITV Digital rented on other multiplexes initially became empty again, but some was rented out to allow new channels to launch. In May 2004, Top Up TV was launched to provide subscription content in unused space on Multiplexes 2 (rented by Top Up TV from Channel 4) and A (rented from SDN). SDN was bought by ITV plc in 2005. In September of the same year, Top Up TV began operating solely on Multiplex A (now owned by ITV plc), as Channel 4 reclaimed the bandwidth on Multiplex 2 for their own services. On 12 October 2005 , ITV and Channel 4 joined the Freeview consortium, meaning that the Freeview package contains television and radio channels across six multiplexes (though existing contracts mean that Top Up TV remains). The future On April 19th 2006, Ofcom ruled that, on request of each Multiplex Operator, the ' Free-to-air channels only' requirement put in place at the launch of Freeview in 2002 may be lifted on Mux B, C and D. The effect of this ruling is that if a Mux operator requests the restriction to be lifted, their multiplex may carry pay-tv services. Ofcom says that the digital television market has changed siginificantly since 2002. Consequently, it believes that this restriction is no longer required. Although Multiplex 2 and A have always been allowed to carry pay services, Ofcom believes that the free-to-air only restriction and the current state of DTT artificially damages the growth of pay tv on the platform. During the consultation, 9 of the 12 responses from broadcasters were in favour of removing the restriction. These, perhaps surprisingly, included the BBC. The BBC agreed that the digital television market had changed substantially since 2002, and that Top Up TV probably couldn't afford the current cost of DTT slots anyway. The BBC suggested that the deregulation should be conditional on a number of further changes to regulation. These included that Ofcom changes the transmission mode of broadcast on all multiplexes from 16 QAM to 64QAM so more services could be squeezed onto the digital terrestrial platform. However, Ofcom rejected these suggestions, saying they were outside the scope of the consultation. Out of the three that opposed, one was Channel 4, which has been putting in place a portfolio of free-to-air channels, and this will see FilmFour appear on Freeview later this year. Channel 4 argued that the number of free channels available has been the major driving force behind the massive success of the platform - there are now more than 10 million Freeview boxes in use. A number of broadcasters requested that their replies were kept confidential. These include ITV and BSkyB . However, it is believed that ITV opposed the plan and BSkyB supported it {Link without Title} . In addition to replies from broadcasters, there were 21 replies from individuals. Of these, 20 opposed the change. The channels on Multiplexes B, C and D are those owned by the Freeview consortium and include the three Sky channels on the platform and the UKTV channels. However, Ofcom believes that in the short to medium term, it is unlikely existing free-to-air channels will convert to pay-tv. This is because, firstly, Multiplex B is run by the BBC, who is not expected to request the removal of the free-to-air requirement. Secondly, due to the nature of the contracts the channel broadcasters hold with multiplex operators and content providers, it is unlikely a channel will be able to change to pay-tv. LIST OF DIGITAL TERRESTRIAL CHANNELS Television channels Text and interactive services Radio stations New channel launches
THE MULTIPLEXES Multiplex 1 Operated by the BBC. Nationwide in 16QAM mode, 18 megabits/second.
Multiplex 2 Operated by Digital 3&4 (an ITV/Channel 4 consortium) Nationwide in 64QAM mode, 24 megabits/second.
Multiplex A Operated by SDN (owned by ITV plc), Nationwide in 64QAM mode, 24 megabits/second.
Multiplex B Operated by the BBC, Nationwide in 16QAM mode, 18 megabits/second.
Multiplex C Operated by National Grid Wireless, Nationwide in 16QAM mode, 18 megabits/second.
Multiplex D Operated by National Grid Wireless, Nationwide in 16QAM mode, 18 megabits/second.
Use of multiplexing technology The astute reader will notice that some of these multiplexes carry a much larger number of services than others. Firstly, a number of services share Bandwidth — so some channels turn off when others are on (for example one will never see CBeebies and BBC Four on air at the same time, as they use the same space in Multiplex B, with CBeebies broadcasting from 6am until 7pm and BBC Four from 7pm onwards; the situation is the same for CBBC and BBC Three ). In addition, some multiplexes have fewer channels so as to allocate more data to fewer services, thus ensuring higher quality (for example, BBC One on Multiplex 1 is carried as a 4.4 Megabit stream, while Sky Sports News typically uses 2 Megabit s per second) . On top of this, the (only used for tests in the Oxford and London areas), 16 QAM and 64 QAM , each with a progressively higher bitrate, at the cost of progressively higher likelihood of signal degradation. Currently multiplexes 2 and A use 64 QAM (and are consequently more prone to poor reception) while the other multiplexes all currently use 16 QAM. Furthermore, multiplexes can make use of Statistical Multiplexing at the MPEG video coder whereby the bitrate allocated to a channel within the multiplex can vary dynamically depending on how difficult it is to code the picture content at that precise time, and how much demand there is for bandwidth from other channels. In this way, complex pictures with lots of detail may demand a higher bitrate at one instant and this can result in the bitrate allocated to another channel in the same multiplex being reduced if the second channel is currently transmitting pictures which are easier to code, with less fine detail. The only channel on the DTT system not to use statistical multiplexing, i.e. has a constant bit rate, is BBC One. This is so the English Regions and Nations can perform a simple transmultiplex, or T-Mux, operation and insert their local version of BBC One over the London feed straight into the existing BBC Mux 1 without any complex or time consuming decoding. New compression technology Better implemented compression technology has provided for two additional television stations on the National Grid Wireless multiplex using the same bandwidth, with the possibility of more to follow on this and some other multiplexes. This technique is only suitable for the multplexes that are identical nationwide. On Multiplex 1 where BBC One is one of 15 regional versions, and BBC Two is one of four national variants (England, Scotland, NI and BBC 2W in Wales) it has proved harder to increase the number of channels carried. The same problem applies to Multiplex 2 with its 19 ITV1 regions and Channel 4 variations (used for advertising rather than programming). {Link without Title} The additional capacity has been achieved by developments in Statistical Multiplexing that allows the broadcaster more additional channels using the same bandwidth. The two slots were made available for bidding earlier this year, and due to the limited capacity on the DTT service in the UK, broadcasters bid in millions in order to gain bandwidth. ITV won the bidding for the first slot (on which it launched Men & Motors on 2 May , 2005 which has subsequently been replaced by ITV Play), and Channel 4 the second. Channel 4 launched E4 +1 , as opposed to its new channel More4 , on the multiplex when the slot became available on June 1 (E4 launched on Freeview on 27 May 2005 ). National Grid Wireless have made a new slot available on Multiplex D using the same compression techniques as above. The 18 hour channel, running from 6am to midnight, became available on 1 December 2005 . Companies interested had until November 1 to submit their bids, with bids said to have reached £10 million, from a set entry bid level of £5.5 million, with 12 separate bidders covering all sectors of broadcasting. This slot was won by Channel 4 , who are currently using it for More4 +1 . The latest compression technology, as now available in codecs like MPEG4 H.264 or Microsoft's WMV , could in principle enable most existing programmes to be converted to high-definition, without any need for more bandwidth. However this will obsolete all existing receivers as new decoder set-top boxes or idTVs would be required. Backwards compatibility is a common technology issue. The BBC, who would like to broadcast High-definition Television on at least some Freeview channels, is considering an alternative method utilising spare capacity at night to allow the download HD program for later replay. DIGITAL SWITCHOVER The British Government has given Ofcom and DigitalUK the joint task of Switching Off The Analogue Signals . The switchoff will occur on an ITV regional basis. The first region to be switched off will be the Border Television region in 2008 , and the last will be the Channel TV region in 2012 . {Link without Title} There remain numerous decisions to make, including how to deal with the very small number of people who have no desire to receive more than the four or five channels they presently have, and those who may find the new technology confusing. Also they will be reluctant to buy a digital box in order to view the channels they have had for free for so long. The BBC has been discussing plans with the government to pay for the equipment for the over 75s by asking for an above inflation increase in the Licence Fee . At each transmitter, three of the analogue transmission channels will be reallocated to a digital multiplex, but at a power level about 10 DB less than the current analogue signals. First of all, the analogue BBC Two signal will be replaced with Multiplex 1. At the same time, scrolling messages will appear on the remaining analogue channels reminding viewers of the impending switchover. One month later, the remaining channels will be switched off, with the analogue ITV1 signal being replaced with Multiplex 2, and the analogue BBC One signal with Multiplex B. At some locations, BBC One, Channel 4 or ITV1 may close first, due to the fact that the BBC Two UHF channel is being deallocated.[http://www.ukfree.tv/simulation.php?i=0 It is expected that whole transmitter regions will switch together. It is up to the multiplex operators as to how many of the 1,074 Relay Transmitter s will join the existing 80 that carry all the multiplexes after switchover. Those which don't will only broadcast multiplexes 1, 2 and B, and therefore will broadcast a cut-down service. This service will carry the 5 analogue channels and their sister stations, but little else. At switchover the transmission mode will change from 16QAM to 64QAM on multiplexes 1 and B (Multiplex 2 is already 64QAM). This will increase the amount of bandwidth on each multiplex, and will allow Five to move to multiplex B. When digital switchover is complete, whole tracts of the UHF spectrum will be clear, leaving only channels 21-30 and 41-62 for digital television multiplexes. This spectrum is useful because of its tradeoff between Bandwidth and Range , and could be very lucrative. {Link without Title} The deallocated frequencies could be used for:
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