The House on Friday backed a plan to require television broadcasters to switch to all-digital transmissions by December 2008, three months earlier than they would have to under provisions of a Senate bill.

House lawmakers also voted to set aside $830 million to help millions of Americans with older, analog TV sets pay for converter boxes so they'll continue to get service in the digital era.

The House deadline for broadcasters to end their traditional analog transmissions is Dec. 31, 2008. The so-called "hard date" was included in a sweeping budget bill.

The Senate measure calls for a hard date of April 7, 2009 — after the March Madness college basketball playoffs. The converter box subsidy is significantly larger — $3 billion.

Differences in both bills will have to be worked out by House and Senate negotiators.

Digital television promises sharper pictures and better sound than analog TV.

But about 21 million households rely on free, over-the-air TV, so they'll need the converter box to keep receiving their television service after the switch to all-digital. Cable and satellite customers would not be affected.

Democratic lawmakers have complained that the House subsidy for converter boxes would only pay for about 10 million households, half the number of homes that would need them. And consumer groups say the $830 million would cover only about a quarter of homes.

"The funding level provided is woefully inadequate to ensure that consumers aren't forced to reach into their wallets to facilitate the government's mandated transition to digital television," said Jeannine Kenney of Consumers Union, the publisher of Consumer Reports.

House Republicans have said they don't expect wealthier Americans to request coupons for the boxes, and they expect the $830 million would cover those homes that really need help.

The move to all-digital will free part of the valuable radio spectrum, some of which will be allocated to improve radio communications among fire and police departments and other first responders.

The rest of the spectrum would be auctioned by the government for an estimated $10 billion, though private estimates put that number higher.

The converter boxes would be paid for with some of the spectrum money raised at auction. The boxes are expected to cost about $50 to $60. The bills in both chambers call for the government to pay for about $40, with the consumer picking up the rest of the cost.