Lawmakers eager to speed the transition to digital television (search) said Thursday the government may need to help millions of low-income Americans keep their analog (search) TVs working.

About 21 million homes, or 19 percent of U.S. households, get their TV signals at no cost using over-the-air antennas. They would be useless by the end of 2006 — the date Congress would like the digital shift to be complete — without also using a converter box.

Digital broadcasts offer sharper pictures than the traditional analog transmissions used in most TV sets. A digital broadcaster has the capability of transmitting high-definition images (search), or could offer multiple channels.

The December 2006 date isn't a hard deadline; according to law it could be pushed back until 85 percent of homes in a market can get digital TV. Nationally, only 12 percent of homes have digital sets, according to the Consumer Electronics Association.

Two leading House Energy and Commerce Committee members — Reps. Joe Barton, R-Texas, the chairman, and Fred Upton, R-Mich., said they might introduce legislation that would eliminate the 85 percent provision in order to speed the transition.

But to do that, Barton, Upton and other lawmakers said Congress may have to ensure that people who use analog TVs with antennas can still use their sets.

Nearly half of the 21 million homes that get antenna TV reception have incomes under $30,000, according to the Government Accountability Office. At a hearing Thursday, witnesses told the panel that a box that could be hooked up to the TV that could convert the digital signal into an analog signal. Each box could cost up to $100.

A government program to help subsidize the cost of the boxes could cost between $460 million and $2 billion, depending on the price of the box and whether there would be income limits.

"If Congress did nothing, those households which rely exclusively on over-the-air television service could see their television sets 'go dark' at the end of the digital television transition," Upton said.

A GAO study released at the hearing said the cost of the subsidy program could increase to between $1.8 billion and $10.6 billion if lawmakers also decided to subsidize a similar converter box for cable and satellite subscribers who could not get digital reception. Most lawmakers, though, focused on the homes that received just antenna TV reception.

Once the digital transition is complete, Congress wants part of the old analog spectrum to be used to improve public safety radio communications.

Another part would be auctioned to wireless service providers; it could be worth billions of dollars for a federal government that this year is projected to have a record $427 billion deficit.

A December 2006 deadline is preferred, and money from the auction could be used to help pay for the converter box subsidy, Barton said.

Rep. Ed Markey, D-Mass., ranking Democrat on the telecommunications subcommittee, said Congress must be swayed first by consumer concerns in setting a hard deadline. Issues such as how the subsidy program would work must be properly addressed first, he said.

Markey also noted how many consumers today are buying new analog sets without being informed by sales clerks of the digital switch.

"Any transition plan that abruptly cuts off analog television service must come only after consumers have been adequately informed of the impending shut-off of service," he said.

Digital signals can only be received by a television with a tuner that can decode such signals. The average cost for a TV with a built-in digital tuner is $950, according to the Consumer Electronics Association.

The Federal Communications Commission has ordered that all new TVs 13 inches and larger be built with digital tuners by July 2007.