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Sound Advice: Into the Deep White Spaces

May 1, 2008 12:00 PM, By Dan Daley

Complications arise over the expansion of wireless devices into the analog spectrum.


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UHF spectrum after Feb. 17, 2009

UHF spectrum after Feb. 17, 2009

But this doesn't solve the issue of how wireless devices will steer clear of each other in the newly purchased ether. So far, one device — made by Microsoft and tested by the regulatory agency — has failed, and furthermore, it reportedly caused interference with existing licensed frequencies in the process. A second device has been submitted to the FCC, and testing has begun. However, underscoring the increasingly political nature of this issue, those who oppose making the white spaces the wide-open spaces — such as the National Association of Broadcasters (NAB), sports leagues, and professional audio equipment manufacturers — have interpreted the results of that second device so far as failures. NAB spokesman Dennis Wharton reportedly said, “Completing a successful transition to digital television ought not to be jeopardized by introducing risky technology that has proven to be unworkable.”

On the other hand, members of the White Space Coalition have claimed that the results of both tests weren't valid because the devices weren't functioning properly and that the NAB and others opposing the broadened use of the white space have exaggerated the preliminary failures.

“We're up against big business — very big business,” says Mark Brunner, senior director of brand management at Shure. The microphone manufacturer has spent much of the last two years intensively lobbying and educating members of Congress, as well as filing briefs with the FCC — the agency that will oversee the auction of the white spaces — in an effort to create some order in a post-digital broadcasting environment. Shure and other opponents of consumer electronics (CE) use of the white space have provided Congress and the FCC with test results, graphic demonstrations of CE device interference, as well as technical alternatives. These include spectrum-sensing technology and listen-before-talk protocols that can act as frequency traffic cops. Shure is also advising a working group from international standards body the Institute of Electrical and Electronics Engineers (IEEE) on amendments to the 802.22 wireless standard that could address the issue.

The problem is that we're living in an increasingly wireless world. As wireless CE devices such as cell phones and PDAs do more, they will get used more. This civilian use of wireless is encroaching on its professional audio applications in many areas — not least of which is installed systems, which themselves are using more and more wireless elements. The installed professional audio applications that have long used these frequency bands are going to have a tough time finding reliable bandwidth with which to use their increasingly necessary and prolific wireless audio systems. Imagine a typical Thursday night on the Las Vegas Strip: 30 hotels each with one or two multi-million-dollar theatrical productions running during primetime. More than 200 channels of wireless in operation. And at a key moment in any of the shows, a toxic burst creates a deafening noise glob throughout the installed sound system — or perhaps worse, produces the deafening silence of a primetime dropout. Imagine an argument on a cell phone breaking into the closing dance number.

The implications are significant for sectors that use ranged professional audio — not the least of which is the installed/integrated systems sector, the core constituencies of InfoComm and CEDIA (particularly InfoComm, with its emphasis on commercial installations). “InfoComm believes that professional audio productions face significant interference risk from the introduction of unlicensed devices in television broadcast bands unless FCC rules are developed that fully protect wireless microphone systems,” says Betsy Jaffe, director of government relations for InfoComm, in an email. “Wireless microphones should be protected from potential interference, as they are critical to effective and reliable communication.”

But it's a sensitive proposition, too. While entertainment entities such as broadcasters and theatrical organizations are raising the loudest opposition, the clients of systems designers and integrators easily fall into both camps: They'll want the wireless audio systems in the corporate theaters and boardrooms to be reliable, but they're also going to want their Blackberries and iPhones not only to work in that same environment but also to network in it.

Uncertainty seems to be all that's certain. Bob Green, director of Audio-Technica's global product strategy, wireless, says that the FCC's failure to precisely define the nature of the unlicensed devices that will use the newly available spectrum, how much of it they'll use, and what constitutes currently authorized wireless devices is clouding reality. “We'd like to see a test period in place after the analog signals are shut off,” he says. “As it stands, no one will know what's really going to happen until that day.”

Systems designers and integrators should watch how this situation plays out over the next few months. What we can hope for is that science prevails over commerce. Once you get the science nailed down, the commercial end of the equation can usually find a way to accommodate it.



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