WASHINGTON DC: The great US digital broadcasting switchover is a just a year away, yet millions of viewers are still clinging to their analog-only television sets.

Latest estimates from regulator, the Federal Communications Commission, show that around 15.5 million households still rely on 'old' technology, an issue that will have to be addressed by a more intense public-service advertising campaign.

The FCC is said to be mulling a plan which would oblige broadcasters to run at least four 30-second ads per day about the digital transition.

That number could reach twelve a day as the February 17, 2009 deadline approaches.

Network and cable broadcasters announced last year they would donate around $900 million (€607m; £451m) of airtime to public-service announcements, which have already started airing.

However, the regulator is concerned the ads are not shown when most people are watching TV, and are aired most frequently between midnight and 6am.

Broadcasters are naturally reluctant to donate more expensive airtime and have put forward an alternative schedule.

This proposes that local stations voluntarily air at least a dozen public-service announcements each week, as well as two separate ads per week on each of the big four and Spanish-language networks.

The FCC will have to decide shortly on its preferred option and set the ad wheels in motion.

The apparent lack of urgency among TV households to take the necessary steps ahead of digital switchover is reflected in their take-up of vouchers redeemable against the cost of settop converters.

Just two million requests have been received so far for the $40 (€27; £29) coupons – two of which are available to every TV home across the nation.

Nonetheless, a new survey by the National Association of Broadcasters reveals nearly 80% of TV households have at least some knowledge of the digital transition, up from 38% a year ago.

Data sourced from Wall Street Journal Online; additional content by WARC staff