With backers of the low-power FM proposal picketing in front of the Las Vegas Convention Center, broadcasters large and small again warned regulators that the proposal to switch on small community stations would result in unacceptable third adjacent channel interference with their stations.

For terrestrial radio stations struggling to keep pace with major shifts in their industry, such as the emergence of satellite digital radio, "Interference is obnoxious," said Lynn Claudy, NAB's senior vice president for science and technology.

Broadcasters recently went to court in an attempt to block the Federal Communications Commission's plan to allocate spectrum for low-power FM stations. Congress has also gotten into the act, with the House Commerce Committee approving legislation that would among other things require a study of the technical issues before low-power services could be launched. A similar bill has been introduced in the Senate.

Nevertheless, FCC officials overseeing the rollout of low-power FM insisted here that there is a groundswell of support for the service by small community broadcasters who want to meet the needs of specific audiences. The officials down-played broadcasters' complaints about interference, but the issue looks like it will eventually be settled in federal court.

Either way, the FCC's defense of low-power FM radio got tougher recently when National Public Radio joined other broadcasters in opposing the plan. NPR engineers also cited concerns about adjacent channel interference.

"The answers [to the question of whether low-power stations would interfere with existing broadcasters] are deep in the technical record at the FCC," NAB's Claudy said.