Katie Jones' television gets 2 ¹/₂ channels. The set receives a crystal-clear NBC channel, a spotty CBS, which means a fuzzy Oprah, and an invisible but still present ABC.

While it might seem odd that the 30-something Ms. Jones of Morningside relies on a "rabbit-ears" antenna atop her television to receive her daily fixture of entertainment, it will seem even stranger when her screen goes completely blank fewer than two years from now.

"I'll probably wake up after New Year's, and my television won't work," said Ms. Jones, after she learned that her television, along with millions of other sets across the country, will become useless in mid-February 2009, after the broadcast industry completes a nationwide digital transition.

Not only is her household one of 21 million that rely on an antenna for its television signal, but Ms. Jones is also one of about 61 percent who knew nothing about the digital transition.

"Will you call to remind me when to get a converter?" she asked a reporter yesterday, shortly after learning that the federal government would eventually supply two $40 coupons for digital converter boxes for every household. "How are they going to let everyone know about the conversion? Just how will they accomplish that task?"

In Washington yesterday, U.S. senators blasted the federal government efforts to tell those millions of people with antennas about the switch to digital-only signals in less than two years.

"I think there's high potential for a train wreck here," Sen. Maria Cantwell, D-Wash., told Federal Communications Commission and Commerce Department officials during a hearing on the digital TV transition.

Lawmakers and advocacy groups have become increasingly concerned that the government isn't doing enough to educate the households that receive only over-the-air TV.

Under federal law, stations must turn off their old analog signals Feb. 18, 2009, and broadcast only in digital. Although cable and satellite systems have promised to convert the signal for old analog TVs, those without new digital sets will need special converter boxes.

Democrats appear poised to push for more money and public service announcements to prepare TV owners. U.S. officials have budgeted $5 million to tell people about the switch and the free coupons that will be available on a first-come, first-served basis to cover most of the cost of a no-frills converter box.

The government is relying on the television industry and consumer electronics makers to do the bulk of the public education, and so far "their efforts have yielded few results," said Senate Commerce Committee Chairman Daniel K. Inouye, D-Hawaii.

A survey released in January by the Association of Public Television Stations found that 61 percent of respondents were unaware of the pending digital switch. "We really do have a long ways to go in this process," said Sen. Olympia J. Snowe, R-Maine.

Government officials said funds were limited, but that they expected awareness to rise as public and private education efforts ramped up. "We have more work to do," said John Kneuer, assistant secretary for communications and information at the Commerce Department, which will run the $1.5 billion converter box coupon program.

The coupons will be available Jan. 1. Federal officials have set up a Web site, DTV.gov, and a toll-free number, 888- DTV-2009 (388-2009), to answer questions.

Mr. Inouye promised Wednesday to take action on the public education effort after listening to complaints from the Leadership Conference on Civil Rights, the National Hispanic Media Coalition and AARP, the organization for seniors. The groups are concerned that poor and isolated people will be disproportionately affected. Mr. Inouye did not say what steps he was considering.

FCC Chairman Kevin J. Martin has requested $1.5 million from Congress for additional outreach. Congress also may press broadcasters to do more to educate TV viewers through public service announcements. Reps. John D. Dingell, D-Mich., and Edward J. Markey, D-Mass., have suggested that the FCC consider requiring TV stations to run those announcements.

The National Association of Broadcasters is creating several public service announcements and will devote free airtime worth tens of millions of dollars starting in December, said Dennis Wharton, the trade group's executive vice president. He noted that broadcasters had the most at stake if people couldn't watch their stations. "There's no question there's a staggering lack of information about this transition, and it's our job to try to correct that," he said.

But Sen. Claire McCaskill, D-Mo., said politicians would bear the brunt of the outrage if TVs went blank.

"They're not going to call you," she told Mr. Kneuer and Cathy Seidel, chief of the FCC's Consumer and Governmental Affairs Bureau. "They're going to call me, and they're going to be mad. When people start calling in, I'm giving them your numbers."