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The entire campaign is of interest because the white spaces broadband issue has been brewing for years, but until now backers have largely said, "Let the science decide!" Since the main objection raised by TV broadcasters and wireless microphone makers is interference, the pro-white spaces alliance (represented by groups like the Wireless Innovation Alliance) have said that the issue should be decided by the nonpartisan Office of Engineering Technology at the FCC, which has been testing the devices.

But it's becoming increasingly clear to the various parties we have spoken with on the issue that the OET won't issue a "yes/no" recommendation. With the second wave of testing now complete and the OET report apparently being drafted, most parties are convinced that it will offer maximum wiggle room to the commissioners and fodder for both sides.

The decision will come down to a nontechnical, political choice (how much likelihood of noninterference do we need to approve this?) rather than a simple binary question (will this interfere or won't it?). That means the campaign for and against white spaces will become explicitly political rather than technical in the next few months.

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Shure said in a press release that the prototype devices (actually technology demonstration devices as opposed to prototypes of future products) “were unable to consistently identify operating wireless microphones or distinguish occupied from unoccupied TV channels.” Philips disputes that interpretation ...

Shure Senior Director for Public and Industry Relations Mark Brunner said the Philips device consistently showed channels to be nearly completely occupied even before wireless mics were turned on, while the other (from the Institute for Infocomm Research , backed by the government of Singapore) had the opposite problem, failing to detect occupied channels even after the mics were turned on.

Monisha Ghosh of Philips Research said the Philips device detected channels as occupied because they were in fact occupied—by television signals that in some cases were too weak for a regular handheld spectrum analyzer to detect. The Philips device detects whether a channel is occupied but does not display the strength of the detected signals or distinguish whether they come from wireless mics or television transmitters. It detects TV signals at a level far weaker (less than -120 dBm) than what is viewable on television or can be picked up by conventional spectrum analyzers, she said.

In the case of the FedEx Field tests, she said that in one round of testing—on the football field itself—the device successfully detected a mic turning on (on Channel 31). At higher locations, it detected that channel as occupied from the start, consistent with what FCC data indicated it might detect, she said. Once the device detects a channel as occupied by any source, that channel would be avoided by a future white space device, so there’s no need to further detect low-power wireless activity on the same channel.

“If a wireless mic is using a channel that already has a DTV or NTSC channel on it, the white space device is actually providing more protection [than a wireless mic],” she said.

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