Jack Kontney /
10.08.2010 12:46 PM
FCC white spaces ruling ensures protection for wireless mic users

On Sept. 23, the FCC issued its Second Memorandum Opinion and Order (MO&O) detailing its intended usage of the vacated TV spectrum among various user types. The order defines the rules of engagement for unlicensed TV band devices (TVBDs), creates specific protections for wireless microphones and further defines the access and usage of the pending national frequency spectrum database.

Wireless microphone users and manufacturers have been at the forefront of this battle, seeking to protect these devices from interference by TVBDs. A new class of consumer and industrial products will help create the infrastructure for a national broadband system aimed at bringing service to underserved areas while purportedly making urban Internet access cheaper, faster, more reliable and ubiquitous. In addition, it is expected that TVBDs will help create a new class of personal wireless devices that offer significantly greater capabilities to mobile customers.

The Second MO&O was hailed as a victory by those on both sides of the debate, providing two TV channels of spectrum for wireless mics in every market while relaxing some key technical requirements for TVBDs. Reading between the lines, that more likely indicates some degree of disappointment on both sides. Mark Brunner and Christopher Lyons of the Shure global group have been focused on the white spaces issue for several years now. “Everybody came out with their positive spin on this news, but frankly, everyone was equally disappointed,” Lyons said. “Taking two TV channels of spectrum out of every market was devastating to the TVBD supporters. The pro audio community needs to be pretty satisfied with the outcome.”

On the other hand, the new MO&O makes significant concessions in the technical requirements for TVBDs, including spectrum-sensing requirement for portable TVBDs being optional instead of required and relaxing the detection threshold from -114dBm to -107dBm. Spectrum sensing would alert a TVBD of other operators in the area (both mics and broadcast stations).

Rather than spectrum sensing, TVBDs will use a national geolocation database of registered users to avoid creating interference. While the specifications for the database are largely unchanged from the FCC’s 2008 MO&O, the ability of smaller users to gain access to such protection will be more limited under the new MO&O.

The good news for wireless mic users is that, to the surprise of many, the FCC will create two dedicated, reserved UHF channels, 6MB in width, specifically for their use. These channels will include one each above and below TV Channel 37 (dedicated to medical telemetry) in every U.S. TV market. This is in addition to mics having access to any channels in range 14 to 20 that are adjacent to locally occupied TV channels. Each TV channel typically accommodates six to eight wireless microphone channels. In addition to these protected areas, wireless microphones will continue to be legal to operate throughout the TV band, as they are currently, though with significantly less protection from TVBDs. As a result, users of modest channel counts of wireless mics and IEMs can expect to find sufficient spectrum for unencumbered operation with virtual certainty.

Shure had encouraged to FCC to set aside dedicated channels for wireless microphones throughout the white spaces debate, dating back more than 10 years. “It’s interesting that we did kind of end up right back where we started,” Shure’s Brunner said. “In fact, our last proposal before the initial rules was actually very similar to what happened. Of course, we had asked for more channels, but you don’t go in low-balling in a negotiation. All sides of this debate were guilty of that, but the FCC did a great job of balancing all the competing interests.”

Lyons and Brunner note that some of the TVBD makers argued against the difficulty of spectrum sensing while at the same time wanting very restrictive access to the geolocation database. “If both had been granted, that would have left the entire pro audio industry vulnerable,” Brunner said. “The FCC saw the wisdom of protecting this large swath of casual microphone users. The ruling makes the entire equation much simpler, since no one will need to be involved in their day-to-day protection. It’s a win-win decision.”

As expected, large installations and events (Las Vegas, Broadway, Super Bowl, etc.) will be able to gain protection from TVBDs by registering with the national database. Access to the database is available to others, but with several requirements designed to discourage abuse, such as 30 days advance notice and the “practicable” use of all available reserved channels.

Perhaps the group most threatened by the recent MO&O is ENG crews in major markets, where spectrum crowding has been an issue for years. Because these crews are deployed unpredictably, they cannot get protection from the geolocation database. And because they operate outdoors or with buildings with their own RF infrastructure, they often must operate in areas where interference is already problematic before the addition of TVBDs (expected to hit the market in the next two years).

“ENG crews didn’t lose any protection,” Lyons said. “It’s just the nature of their environment that creates problems. Fortunately, they will have access to protected channels now and can coordinate with any other TV stations that might be covering the same news events, just as they do now. Since you can’t schedule when or where news will happen, ENG crews will need the advantage of the new protected channels more than anyone.”



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