UK digital television will start to lag behind other European countries without a longer-term HD on DTT strategy, the Digital Television Group (DTG) has warned.

Ofcom confirmed last week that it wants to reorganise the DTT multiplexes, upgrade one with new transmission standards and, in turn, allow public service broadcasters the chance to run up to four HD services.

DTG director general Dermot Nolan welcomed confirmation that there will soon be HD channels on Freeview, but argued that the proposals are only short-term solutions.

“Ofcom's horizon appears only to be the launch of an interim HDTV solution in the run-up to digital switchover, but what is going to happen afterwards?” he asked.

“If you look at France, it hasdedicated three multiplexes to HDTV. Its 12-channel HD system will be on the air before the year is out. That is an interesting comparison.”

Proposed upgrade

The proposed adoption of the DVB-T2 transmission standard for DTT has caused concern among the trade association's manufacturing members. Many are reluctant to build receiver equipment until the standard has been formally ratified, potentially delaying the roll-out of HD services.

“People have to make an investment decision about DVB-T2 on whether it is going to be a commercial prospect,” said Nolan. “They won't make that until they're clear about the regulatory framework. Bear in mind that Ofcom's proposals have to be approved by government and that will take time.”

As part of Ofcom's proposal, the BBC will receive one of the four available HD channels, with ITV, Channel 4, S4C and Five left to compete to win the other three.

Roll-out of HD will follow digital switchover and the first regions to have their analogue signal turned off will be the first to get HD channels. All viewers will require a new set-top box to receive Freeview HD channels.

Ofcom chief executive Ed Richards said: “This is a once-in- a-lifetime opportunity to upgrade digital terrestrial television. It offers benefits for broadcasters, which will be able to launch services without using any new spectrum, and viewers, who will have access to new channels and services on free to air.”

Issues of quality

Dr William Cooper, a former head of BBC Broadcast and the man behind independent consultancy informitv, said Ofcom's proposal for HD on Freeview will not deliver the highest possible picture quality to viewers.

"Ofcom appears to assume that high-definition will be delivered at under 10Mbps, in order to fit the additional channels into the existing capacity," said Cooper. "That could mean using a 720 line progressive format, rather than 1080 interlaced lines. Although it may be argued that most consumers will not be able to tell the difference, the issue of high-definition formats is still a matter of debate among experts.

"Ofcom proposes to leave the decision on line standards to broadcasters. It may be technically possible to transmit 1080i in under 10Mbps, but that is considerably less than the capacity allocated to current high-definition broadcasts in that standard.

“The assumption is that considerable improvements can be made in compression and transmission technology. The risk is that broadcasters end up compromising on quality in order to provide more channels, which is already an issue for digital terrestrial television."

The DTG is the trade association for digital television. It represents broadcasters and equipment manufacturers.

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