White Space Battle Continues

Wireless mic makers, broadcasters appeal FCC rule
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Last November's decision by the Federal Communications Commission to allow "white space" or television band devices (TVBDs) to operate below 698 MHz took the next step towards implementation on Feb. 17 when it was published in the Federal Register. The years-long lead up to the decision, which also required wireless microphone, in-ear and communications systems to cease operating in the so-called 700 MHz band by that date, has seen a public war of words waged between professional audio equipment manufacturers and prospective TVBD-makers.

With the publication of the decision the fight has now moved to the courts. The Feb. 17 publication automatically triggered a 30-day window for the filing of any Petition for Reconsideration and set a 60-day clock running for the Federal Court of Appeals process.


The pro audio industry knew about the switchover from NTSC to ATSC operation and the auctioning off of the spectrum vacated by analog television and has been preparing for some time.

"We're in a unique situation because we knew about 10 years ago when they started this digital dividend stuff that the 700 MHz band was going to become impractical for wireless mics," said Jackie Green, vice president of R&D/engineering, Audio-Technica. "So we stopped product development in that band in 1998."

Indeed, all of the mic-makers have discontinued production of products for the domestic market that operate in the 700 MHz band. The manufacturers even instituted various initiatives to educate customers. "There's no way anybody can claim they didn't know about it," said Karl Winkler, director of business development for Lectrosonics, noting that customers were notified in 2007 that 700 MHz band equipment would be special order-only by early 2008.

The major manufacturers have implemented a variety of Web and telephone support programs as well as rebate, trade-in and retuning schemes to help customers relocate out of the affected spectrum. Joe Ciaudelli, Sennheiser's consultant for professional products, notes that the company offers a multi-tiered system, from a simple flat rebate through retuning at roughly $100 per component all the way up to a platinum package: "This is the 24-hour roadside assistance; call us and if it's a critical issue we'll jump on a plane and come out and fix it."

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The use of wireless mics in everything from Broadway to the Grammys could be impacted by the use of new TVBDs in the TV band. But with so many legacy FM systems already in the field it's no surprise that manufacturers and advocacy groups are now seeking legal recourse against the FCC's decision to allow TVBDs to share the increasingly limited RF spectrum available to pro audio users.


According to Mark Brunner, senior director, public and industry relations for Shure, a company that has taken something of a leadership role in questioning everything from test procedures to aspects of the decision, the company filed a Petition for Reconsideration in time for the March 19 deadline.

In addition "the NAB in combination with MSTV [Maximum Service Television] joined forces in a Federal Court appeal, which they filed in Washington D.C. District Court," he said. "A somewhat ad hoc association of theater groups, including the Broadway League, joined forces with many of the national sporting leagues, ESPN and News Corp. in a Federal Court appeal."

In general, pro audio manufacturers believe that the FCC decision accepted that their products should take priority over TVBDs, which will be required to incorporate technology to prevent interference with wireless audio systems. Green points out, "[RF mics] still operate under Part 74, they're still protected as secondary devices for licensed users in band 2 to 51—nothing has changed."

Adds Ciau-delli, "If reality plays out the way the FCC stipulates it should, then production professionals don't have a lot to worry about." But that's a big if, he says: "If the TVBDs don't behave the way they're supposed to, what is the FCC going to do? Will it be recalled, will there be a penalty? None of this was detailed."

Brunner adds, "we felt that the overall outcome offered at least the semblance of adequate protection for wireless microphones," but it's the details that Shure is questioning in its filing. Chief among them is the spectrum sensing technology—as yet largely unproven—that TVBDs must include. A number of the TVBD-makers are now downplaying the role of spectrum sensing and support an expansion of the FCC's recommendation that two channels be set aside for RF audio gear use in the 13 major markets, Brunner said.


Another issue is the database of users that the devices must lookup. As Brunner notes, touring acts can make last-minute adjustments to their schedules. News crews may be called out to special or unforeseen events. "We want to make sure that the database is operating in as close to real time as possible," he says.

The prospective TVBD manufacturers, who include Motorola, Microsoft and Dell, want currently unlicensed RF equipment users excluded from the database. "Shure believes that all users should have access to the database, as long as they can provide the information that is required," Brunner said.

There are also questions regarding the sensitivity threshold for spectrum sensing devices. "The final rules ended up looking for a spec of –114 dBm, which is a fairly weak microphone signal," Brunner said, noting that the IEEE is recommending a level of –107 dB and U.K. regulatory body Ofcom suggests –126 dB.

But there is unlikely to be much response from the FCC for some time, he notes: "We don't have a new chairman there yet, and acting commissioner Copps isn't going to open a Pandora's box until there's a new boss in place."

Whatever safeguards are eventually put into place, James Stoffo, a wireless frequency coordinator for such high profile events as the NBA Finals and Super Bowl, predicts there will be interference from TVBDs. The devices will not be able to sense a push-to-talk intercom if it's not in currently use, for example, he said. Noting also that audio professionals use big, helical, directional antennas to maximize signal pickup, he added, "with a TVBD, the antenna is a little teeny portion of a quarter-wave whip that's right next to someone's body, which is absorbing RF. The chances that a TV band device would even 'see' a microphone are really slim to none. I'm skeptical that these will work."

Looking ahead, Stoffo believes RF professionals will have a tough row to hoe. "When I got into this business we had everything from 470 MHz to 806 MHz. Now we have digital and analog TV and we're about to lose 108 MHz of spectrum. It'll become extremely congested and I think that, over the next two or three years, people are going to have to take wireless operation a little more seriously to get things to work."