Exactly what do you get? Digital Q&A Freeing up the bandwidth The technology: pros/cons

Mr Smith said the switch could take place between 2006 and 2010, but he told broadcasters at the Royal Television Society Convention in Cambridge that viewers' interests must come first.

The current free channels must be as widely available as they were now and the price of equipment to receive free-to-air services must come down.

Mr Smith also outlined his aim that following the switch over from existing analogue to digital television, every home in the country with a television and telephone would have access to the Internet.

He said: "This revolution is not just about the young and trendy. It is about everyone - because all parts of our society can and should benefit."

Granada Chief Executive Charles Allen welcomed Mr Smith's speech, "particularly the timetable, which is very important".

BBC Broadcast Chief Executive Will Wyatt gave it "three cheers".

He said: "It is bold in its timetable and genuinely exciting in the vision that sees digital television as something that the whole population must have access to."

£8bn windfall

BBC Media Correspondent Nick Higham: "Switching to digital is the biggest change since the introduction of colour"

So far more than 1.5m households have signed up to digital television, either through Sky Digital's satellite, or from ONdigital's "terrestrial" services which can be received through a conventional aerial.

Commercial broadcasters who have invested billions setting up digital television have been urging the government to set a date for switching off analogue terrestrial signals, to encourage its take-up by consumers.

The move also has attractions for the government, which it is estimated will net £8bn for the public purse by selling off the waveband capacity freed by analogue switch-off.

But Mr Smith has resisted naming a date to switch off or even setting a timetable to do so, until now.

Accessible price

Before switch over, digital services will also have to be available to 99.4% of the population.

The BBC's Jean Gordon reports on what Chris Smith said

The Culture Secretary also wants to make sure people on low and fixed incomes can buy digital equipment at an accessible price and plans to establish a test for the affordability of equipment.

Twice-yearly reviews would assess progress towards the criteria, Mr Smith said.

A Viewers' Panel would be set up to offer a "reality check", and be made up of representatives from the Consumers' Association, National Consumers' Council, Voice of the Listener and Viewer and pensioners' organisations.

"Free" set top box offers from Sky Digital and ONdigital have received wide publicity, but are only available to pay-TV subscribers who pay upwards of £6.99 a month.

Viewers who only want to receive the current five free-to-air analogue channels in digital are barely catered for at the moment, but manufacturers promise mid-range sets soon.