Writing to FCC Chairman Kevin Martin, House Commerce Committee Chairman John Dingell (D-MI) said the FCC should consider licensing at least a portion of available spectrum in the digital TV “white space” bands, noting that “a licensing regime could help mitigate the impact of harmful interference to incumbents in this spectrum.” Dingell’s plea stands in contrast to proposals, championed by Google and Microsoft, calling for unlicensed usage of white space channels. While the FCC continues to test prototype white space devices to assess their impact on adjacent licensees, adjacent television broadcasters and providers of wireless microphone services that fear potential interference from unlicensed white space operations continue to lobby against the Microsoft-Google proposal. Alternatively, wireless industry players are backing plans submitted by the Rural Telecommunications Group and FiberTower Corp. that call for the licensing of white space channels. Other proponents of a licensed approach include wireless association CTIA and the Rural Cellular Association, which has urged the FCC to auction white space channels to wireless entities on a geographic basis. Proclaiming, “these particular bands of spectrum are extraordinarily valuable,” Dingell told Martin that the agency should “carefully and deliberately weigh each proposal prior to reaching any tentative or preliminary conclusions.” Meanwhile, a key manufacturer of wireless microphones proclaimed this week that field tests conducted by FCC engineers during an NFL exhibition game “conclusively show that spectrum sensing white space devices will cause harmful interference to wireless microphones during live events.” Tests conducted during the NFL event last Saturday used prototype devices developed by Phillips Electronics North America and by the Singapore-based Institute for Infocomm Research (IIR). During four of six tests at various locations within and outside the stadium (and with test mics turned off and on), the Phillips device found all channels occupied. The IIR device detected activity on four out of eleven wireless mic channels and also picked up digital TV signals. A spokesman for wireless microphone maker Shure, Inc., said that, “given the poor performance of these sensing devices, there is no reason to believe that . . . other proposed protections, such as beacons, will be any more capable of providing reliable and robust interference protection.”