The National Association of Broadcasters (NAB) warned lawmakers on Capitol Hill today that a proposal to allow the FCC to auction off broadcast spectrum could undermine mobile television.

It would be "virtually impossible" for broadcasters to launch mobile television services if they were forced to move to a lower band as a result of the proposed spectrum auctions, NAB President and CEO Gordon Smith said at a hearing today on spectrum and public safety before the House Subcommittee on Communications and Technology.

"If, as part of the television band reallocations, stations are moved from the UHF band to the VHF band, the deployment of mobile DTV will be severely limited," Smith said in his written testimony. "It is well established that operating Mobile DTV in the VHF band is very challenging and virtually impossible in low VHF where ground noise causes harmful interference."

The FCC wants lawmakers to let it conduct voluntary auctions of television broadcast spectrum which would allow companies to sell off under-used television airwaves. The spectrum would then be used for mobile broadband services. The NAB has been wary of the plan, warning that broadcasters may be forced to relinquish their spectrum.

Smith wants Congress to mandate that no station is forced to share a channel with another station or required to move to a channel in a different band as a result of the proposed auctions.

Smith also asked the committee to limit the FCC a one-time-only auction of voluntarily relinquished television broadcast spectrum, arguing that "multiple auctions could severely undermine broadcasters' ability to attract capital for long-term investment."

CTIA also testified at the hearing. Chris Guttman-McCabe, the group's vice president of regulatory affairs, asked lawmakers to be more aggressive in their efforts to free up spectrum currently used by the government. Guttman-McCabe also expressed some concern about provisions in pending incentive auction legislation that could make it difficult to clear the bands after the spectrum is sold.

The Congressional hearing on spectrum and public safety comes amid a flurry of legislative activity this week on a bill that would advance the creation of a national mobile broadband network for public safety and allow the FCC to conduct voluntary auctions of broadcast spectrum.

Yesterday, California Democrat representatives Henry Waxman, ranking member of the House Energy and Commerce Committee, and Anna Eshoo, ranking member of the House Communications and Technology Subcommittee, circulated their own version of the legislation.

The draft bill was the second to hit the House this week, after Michigan Democrat John Dingell and Texas Democrat Gene Green introduced their own version of the legislation on Monday.

The competing House bills are companion legislation to a similar proposal making its rounds in the Senate. Lawmakers are trying to get the bill passed before the 10-year anniversary of the 9/11 terrorist attacks on Sept. 11.

Separately, a proposal that would create a five-year moratorium on discriminatory state and local taxes on wireless services passed the House Judiciary Committee yesterday, and will now go before a full Congressional vote. The legislation's companion bill in the Senate is still in committee.