"We think it's an enormous market for broadcasters and equipment makers alike," said John Taylor, a spokesman for LG Electronics, which is developing prototype mobile gadgets with digital tuners, such as navigation devices for hikers and combination wireless phone/TV handsets.

The company is one of several industry players racing to develop protocols that could become the industry standard for mobile DTV.

Major broadcast groups such as Belo, Cox Television, Fox, Gannett, NBC, Post-Newsweek and Tribune Broadcasting, representing more than 420 television stations, are behind the push to bring local broadcast content to video displays built into automobile headrests and devices that fit into pockets.

Also participating is the Association of Public Television Stations, a nonprofit representing more than 350 stations. Broadcasters recently formed the Open Mobile Video Coalition to coordinate efforts and lobby in Washington. Coalition sources were not immediately available for content.

In comments Wednesday,to the FCC, the group expressed opposition to unused television channels known as "white spaces" being used by technology players such as Google, Hewlett-Packard and Microsoft for high-speed Internet applications. They are concerned about interference with transmissions to mobile television devices. Broadcasters are equally worried about disruptions to digital reception in homes.

"The added dimension of mobile reception enabled through DTV technology is an essential consumer value and public-service aspect of the DTV broadcast transition -- and must not be compromised," the coalition wrote. "Adding the risk of an untold number of unlicensed, potentially interfering devices transmitting in the TV spectrum is not in the national public interest."

The White Spaces Coalition, which represents tech companies seeking to use the frequencies, insists that interference concerns are overblown.

The business models for the service are still being formulated, but Taylor said some providers, such as wireless carriers, might charge monthly fees for mobile reception. Broadcasters also could charge for premium packages of sports or movie programming beamed to handheld units.

FCC rules governing the transition of broadcasters to digital contemplate subscription-based DTV, mandating that 5 percent of revenues from such services go to the U.S. treasury. The requirement was adopted because broadcasters are licensed to serve the public-interest via airwaves they obtained for free.