On Wednesday, the FCC's Office of Engineering Technology (OET) issued a report that conditionally supported use of wireless devices that could access unregulated spectrum, or white spaces, that will be freed up in 2009 when a government-mandated switch to digital television takes effect.

FCC Chairman Kevin Martin said Wednesday that white spaces could be used as long as they did not interfere with broadcasters.

However, NAB Executive Vice President Dennis Wharton said Thursday that use of white space by unlicensed wireless devices will harm television reception. The FCC misinterpreted its own report, Wharton said.

"It would appear that the FCC is misinterpreting the actual data collected by their own engineers," Wharton said in a statement. "Any reasonable analysis of the OET report would conclude that unlicensed devices that rely solely on spectrum sensing threaten the viability of clear television reception. Basing public policy on an imprecise Cliffs Notes version of a 149-page report raises troubling questions."

In FCC testing, a Microsoft "prototype sample device" malfunctioned, and in laboratory measurements, the adjacent channel signals "significantly degrade detection capability" of devices, the NAB said, referencing the FCC report.

"Overall, the optimistic tone of the Executive Summary of the FCC's OET evaluation does not match the actual test results documented in the report, which clearly show that spectrum sensing is not a reliable technique," The NAB statement said.

Also voicing concern over the FCC report are sports leagues, Broadway theater groups, cable operators and networks, wireless microphone manufacturers and religious groups, the NAB said.

Google and Microsoft have advocated for use of the white spaces for wireless broadband service. As part of its campaign, Google launched FreeTheAirwaves.com in August.

The television white spaces issue is currently on the agenda for the November 4 FCC meeting, according to the FCC.