Ofcom won't use actual demonstrations when it conducts a new round of research to find the best use for analogue frequencies after switch-off.

Participants in the first round of mass-market research will be offered 'showcards' describing new services like hi-def, mobile TV and local TV.

But the survey will try to reach people who have already used some of the services, and other groups such as those who have HD Ready TV's but not HD sources, people with only small screens at home, people with little interest in digital technology, those in rural areas, and those who can't afford new services or technology.

The results will be compared with the original Digital Dividend research from 2006, which was widely criticised for asking people about new services which few had experienced.

None of the participants in the original research were shown demonstrations of the technology and services being studied.

But the new services will be demonstrated in a series of large discussion groups around the country, to which Ofcom's researchers will invite a cross-section of the public.

Ofcom said: "Following discussion of potential sources of private and social value, the groups will rate and rank services from both perspectives. The research will also seek to establish views on a range of future scenarios for penetration and use of different technologies."

The results of the new research should be published before the end of this year.