Expressing concerns that unlicensed wireless devices would interfere with church services, megachurch pastor Rick Warren has urged the US Federal Communications Commission to not open up television "white spaces" for unlicensed use when the agency meets on Nov. 4.

Warren who leads the 25,000-member Saddleback Church in Lake Forest, Calif., voiced his objections in a letter sent to FCC Chairman Kevin Martin last week. The letter was sent days after the FCC's engineering and technology office released a report that gave a green light to the Commission to allow unlicensed users to access the unused spectrum.

Allowing new unlicensed devices to enter the picture would interrupt the church's "most sacred time of the week" - church services, said Warren in the letter.

Like thousands of churches across the USA, Saddleback uses wireless microphones during its worship services. New devices could cause interference because in some cases they occupy the same or adjacent channels as wireless microphones.

"If the FCC were to carelessly loosen the standards and open them to these respective frequencies of new unlicensed devices, the Commission will cause immeasurable disruption to our ability to manage static and audio dropouts," wrote Warren, whose church holds 34 services each week.

"Solutions to this situation will cause houses of worship will have to invest unknown resources to battle the interference from unlicensed mobile wireless devices."

Warren joins the National Religious Broadcasters and another well-known megachurch pastor in the "white space" debate. In early October, Joel Osteen, senior pastor of the 40,000-member Lakewood Church in Houston, also sent a letter urging the FCC to block devices with questionable test results to use the white space.

The letters by Warren and Osteen aren't the first time religious broadcasters have sounded off against the use of white spaces. Last October, Osteen and a Saddleback worship pastor were among the church leaders that signed a similar plea to FCC.

Currently, television white spaces go unused, acting as buffer zones between the occupied television frequencies. The debate over how these unused frequencies are used has been intensifying as the February 2009 conversion deadline from analog to digital transmission approaches.

On Nov. 4, the FCC is scheduled to consider a proposal, supported by chairman Martin, that would up the white-space spectrum for unlicensed use.

The upcoming vote has alarmed the National Association of Broadcasters, which has asked FCC to delay the vote to open up a 60-day comment period on the white-space proposal.

The call by NAB is supported by big TV networks, several members of Congress, a slew of musicians - including Dolly Parton, Neil Diamond, the Dixie Chicks, Clay Aiken, and Guns N' Roses, major sports leagues - including the NFL, MLB, NBA, and NASCAR, and dozens of other groups.

Google, Microsoft and HP are among the big tech companies and wireless device manufacturers which view the unused frequencies as carrying huge potential for making wireless broadband more accessible to both urban and rural areas.

Those who oppose opening up the spectrum, however, point to less-than-stellar test results that show interference still occurs. According to the recent report, some wireless devices failed to properly detect which frequencies were already occupied by wireless microphones.