WASHINGTON – The Federal Communications Commission is proposing a ban on certain types of wireless microphones and has begun an investigation into how the industry markets its products.

Consumer groups alleged in a complaint last month that users of the ubiquitous microphones, including Broadway actors, mega-church pastors and karaoke DJs, are unwittingly violating FCC rules that require licenses for the devices.

The Public Interest Spectrum Coalition accused manufacturers of deceptive advertising in how they market and sell the microphones, which largely operate in the same radio spectrum as broadcast television stations.

The agency, in a notice released Thursday, said its enforcement bureau had opened an investigation. The FCC also is proposing that the sale and manufacture of some of the devices be banned.

“These actions would ensure that low power auxiliary operations do not cause harmful interference to new public safety and commercial wireless services in the band,” the agency said.

Most owners of the microphones are unaware that FCC rules require them to obtain a license.

Wireless microphones that operate in the same frequency bands as broadcast TV stations are intended for use in the production of TV or cable programming or the motion picture industry, according to FCC rules – not karaoke.

The FCC rarely enforces the licensing requirements on the microphones because there have been so few complaints. The microphones are programmed to avoid television channels.

But the looming transition to digital broadcasting, which takes place Feb. 17, has forced the FCC to act.

Channels 52 through 69 in the UHF television band, currently used by broadcasters, will be vacated as they convert to digital broadcasting. The government sold that section of airwaves for $19 billion in the FCC's most successful auction in history. Other parts of that spectrum will be used by paramedics, police and firefighters.

The concern is that microphones that operate in that range may cause interference for the new licensees. It's not known how many wireless microphones operate there, but Harold Feld, a lawyer for the consumer groups, says the total is likely more than 1 million, based on a trade journal estimate.

“These are the favored frequencies because they can be run at lower power and can be used for very high-quality audio,” Feld said.

Also raising the profile of the wireless microphone issue is the fact that the FCC is currently considering whether to allow companies to use the airwaves spaces between television channels for transmitting wireless broadband signals.

Consumer groups and some of the nation's largest technology companies say these “white spaces” represent enormous potential to make broadband more accessible.

Microphone makers, Broadway theaters, the Grand Ole Opry and other users of the devices have objected to the FCC over future white-space devices because of fears about interference, even though many of them haven't been granted government licenses for the microphones they're using.

Shure Inc. of Niles, Ill., told The Associated Press last month that it had stopped selling microphones that use the potentially troublesome frequencies in November 2007. The company did not immediately return a call requesting comment Thursday, but has said it complies with all FCC requirements and “has never engaged in deceptive advertising practices.”

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