Wireless microphones were operating in spectrum occupied by television stations but didn't interfere with broadcasts during recent tests of new wireless broadband devices in Maryland, says a group pushing for government approval of the new devices.
The tests showing wireless microphone use of television spectrum suggest that new wireless broadband devices won't interfere with TV signals, said representatives of the White Spaces Coalition, a group of tech vendors.
The U.S. Federal Communications Commission field tests of prototype wireless broadband devices this month found wireless microphones operating, likely against FCC rules, in spectrum occupied by television channels, according to a Tuesday filing by Ed Thomas, a tech adviser to the White Spaces Coalition and a former chief of the FCC's Office of Engineering and Technology.
The mics "weren’t interfering with TV channels, which is sort of our point," said Jake Ward, a spokesman for the White Spaces Coalition, a group that wants the FCC to approve the use of wireless broadband devices in unused spectrum designed for TV channels. "These mics were broadcasting at much higher volumes than a [broadband device] would, with no interference."
The FCC tests were designed to check whether the prototype broadband devices would interfere with wireless microphones at a football game and a theater production. A prototype device at the football game did not interfere, but it malfunctioned when it did not identify any unused spectrum in which to operate.
Television broadcasters and wireless microphone manufacturers have opposed the coalition's efforts to get the FCC to approve wireless broadband devices for use in spectrum, called white spaces, designed for television stations but not occupied. The National Association of Broadcasters (NAB) and microphone makers such as Shure say there's a risk that the broadband devices will interfere with TV and wireless microphone signals.
Members of the White Spaces Coalition, including Microsoft, Google, Dell and Intel, have argued they can build devices that will identify occupied TV spectrum and broadcast elsewhere. But the coalition's Tuesday filing to the FCC said wireless microphones used at FedEx Field in Landover, Maryland, and at the Majestic Theater in New York City during tests this month operated on occupied TV spectrum.
In Landover, the wireless mics operated in channels occupied by four television stations, while in New York, the mics used spectrum occupied by six TV stations, the filing said. In Landover, wireless mics operated in spectrum used by the WUSA TV station to deliver a high-definition broadcast of the preseason Washington Redskins game that day, Thomas wrote in the filing.
"Although other devices have apparently been operating in their bands for years, broadcasters have not objected to the very scenario they claim would justify prohibiting personal/portable white space operations," Thomas wrote. "Broadcasters have for years acquiesced to these types of co-channel operations."
An NAB spokesman said wireless broadband devices could cause problems because they're likely to have a larger geographic footprint than wireless mics.
"In our view, there's a huge difference between wireless microphones and the unlicensed white-space devices proposed by Google and Microsoft," said Dennis Wharton, the NAB's executive vice president for media relations.
Wireless mics operate in geographically limited areas and generally have small distances between the mics and the receivers, he said. They also are generally operated by "trained professionals," he added.
Those factors limit any interference to TV signals, Wharton said. "By contrast, the proposed white-space devices would be mass-produced and potentially operated by millions of untrained consumers in unlimited locations," he added. "Hence, under this scenario, we believe the interference implications and threat to clear television pictures would increase exponentially."
An official with microphone maker Shure also discounted Thomas' filing, saying the White Spaces Coalition is trying to play down the malfunctions of broadband devices in several recent tests.
The filing "seems to be nothing more than an attempt to deflect the commission's attention from the poor results that prototype white space devices delivered during the recent field tests," said Mark Brunner, Shure's senior director of public and industry relations.
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