Microphones

FCC Update: Sharing Air

1/13/2017 4:55 PM Eastern
TAKE AWAY

The radio frequency spectrum available for wireless microphone, in-ear monitor and communications systems is about to get smaller, now that the Federal Communications Commission’s Incentive Auction is nearing the end of its initial phase. Happily, the dire predictions of recent years that the sky is falling have not come to pass, with the chunk of spectrum in the 600 MHz band that will eventually be off limits diminishing with each successive, unsuccessful stage of the auction.

The FCC drew up its 2010 National Broadband Plan in response to the American Recovery and Reinvestment Act, a stimulus package passed by Congress in 2009. Intended to maximize access to broadband capabilities by consumers, private businesses and the public sector, the FCC’s plan included the reallocation of certain TV broadcast frequencies. Broadcast entities in each TV market were encouraged to auction off TV channels to make way for new mobile wireless services in the vacated “white space” that, among other proposed benefits, could extend the reach of broadband to low-income and rural communities.

To achieve the plan’s goals, telecommunications providers demanded prime UHF spectrum, where signals can be transmitted for miles and pass through physical obstructions with relative ease. The FCC’s Report & Order called for the potential clearing of UHF spectrum from 566 MHz (TV channel 30) and above, which would have left the wireless audio community with about 60% less spectrum—96 MHz, instead of the current 228 MHz—in which to work. The FCC drew up 12 scenarios, from 144 MHz of cleared spectrum to just 42 MHz, with the target being lowered at each stage of the auction if bids failed to meet the broadcasters’ asking prices. After the first three stages of the auction did indeed fail, stage four, set to begin on December 13, reduces the clearing target to 84 MHz, beginning above Channel 37 at 614 MHz. “In general, I’m very pleased,” says Joe Ciaudelli, Director, U.S. Spectrum Affairs for Sennheiser, commenting on the auction entering stage four. “We are going to lose some spectrum, but we got a number of concessions—access to alternate frequency ranges—based on a worst-case scenario with the auction.” Those concessions were obtained through years of discussions between the FCC and pro audio equipment manufacturers, operators and industry advocates, including the DTV Audio Group.

Wireless mic manufacturers have stayed abreast of the changing RF landscape, introducing new products that operate in various alternate frequency bands, including parts of the 900 MHz band, around 1.4 GHz, the unlicensed 1.9 GHz DECT and 2.4 GHz Wi-Fi bands, and above 6 GHz. “We began looking into alternative wireless technologies prior to the DTV transition,” says Jackie Green, President and CTO of Alteros, the subsidiary launched by Audio-Technica specifically to leverage the company’s technical abilities into products designed for the future—both the future spectrum conditions and the future of digitally constructed, operated and networked gear providing maximum performance and workflow interoperability.

“The DTV transition resulted in a 40% reduction in the available TV channel—VHF and UHF—operating spectrum, while wireless microphone usage has been increasing approximately 8% per year. We did not even have to consider the current 600 MHz auction to recognize that large events and venues were already feeling the effects of operating in increasingly crowded spectrum,” she says.

Mark Donovan, CTS-D, CTS-I, AudioTechnica Sales Engineering Manager, observes that discussions on the future for wireless mics have typically focused on the loss of spectrum. “What tends to get overlooked is the highly dynamic nature of the remaining spectrum. It’s fairly simple to determine the licensed broadcast entities occupying bandwidth, but the unknown and unlicensed users that come and go add a high degree of uncertainty to operation.” Consequently, “The new spectral landscape will require users to consider multiple technologies in multiple bands in order to achieve the desired number of channels, audio quality and trouble-free operation,” he says.

“What is really important is to take note of what the new band plan will be after the auction,” advises Mark Brunner, Shure’s VP Corporate and Government Relations. “It’s important to keep your eyes on both the VHF and the UHF TV assignments that will be made post auction, because there will be changes in both. Understand which products you may have in inventory or which products may be in some of your installations that would be affected by this. Get a handle on the impact and a transition time for getting functioning equipment that complies with the new band plan installed.”

It is also worth noting that, unlike the switchover from analog to digital TV broadcasting in 2009, during which RF mic operators had to vacate the 700 MHz band, this time around there are no government funds allocated to defray users’ costs to reequip with new products or retune existing gear.

There is a surefire way for pro audio wireless operators to maximize their options. “If you are eligible to obtain a license, get a license,” stresses Ciaudelli. “In years past there have been entities that have been eligible but they didn’t go through the procedure. Functionally they didn’t need to, but those days are over. The FCC is making a much clearer distinction in these latest rulings between licensed and unlicensed operators.”

Licensed professionals have a portfolio to work with, he continues, putting critical links in UHF and at 1.4 GHz with less critical links in the unlicensed 2.4 GHz band, for instance. At the opposite end of the scale, operators such as bar bands, karaoke singers and smaller churches have a variety of choices in the unlicensed bands. Sennheiser has addressed the challenges of the new RF landscape with, among other options, products in the unlicensed DECT band (1.9 MHz), such as its Speechline system for conference and lecture applications.

But unlicensed professionals are caught in the middle, Ciaudelli points out. “[The FCC] picked an arbitrary line: besides broadcasters, if you routinely operate 50 wireless mics or more as a sound company or a venue, you’re eligible for a license. We are very pleased that licensed eligibility has been expanded; it was long overdue. But there are hundreds of non-profit performing arts centers, for example, who are staging extraordinarily high-end professional productions, but they’re not using 50 mics. This is something we’re still communicating with the FCC on. The message I’ve been trying to reiterate is that unlicensed does not equate to unprofessional.”

The first product from Alteros is the GTX UWB, a 6.5 GHz Ultra Wideband wireless microphone system. It enables up to 24 transmitters to be used simultaneously in a single location—across a network of 32 coordinated receivers and with a transmitter-to-receiver range of approximately 100 feet—without any concern for frequency selection, coordination or interference to other equipment. As a fully digital system, says Green, “There is no modulated carrier to distort, interfere or intermodulate.”

The system is designed to be operated in a congested environment with none of the studio-to-studio or even building-to-building interference common to today’s wireless systems, she continues. “In a crowded and challenging RF environment, the GTX UWB Wireless Microphone System provides immediate spectrum relief to locations in which traditional carrier-based wireless systems are experiencing difficulties due to spectrum crunch.”

Operating well above the frequencies currently under threat by the FCC broadband plan, the product represents a secure investment. “However, spectrum is not the only change on the horizon,” says Green. “As work becomes more complex, gear must be able to handle new complex workflows. The GTX UWB Wireless Microphone System breaks the boundaries of wireless equipment, and Alteros looks forward to the development and release of additional products and tools that will keep users competitive with outstanding operation in the face of changing spectrum and environments.”

In addition to developing products for alternate frequency bands, mic-makers have also been working on increasing the capabilities of their products in the changing RF environment. A major focus for any mic manufacturer is the ongoing drive for spectral efficiency.

“People have a misconception that you’re running a dozen microphones and their frequencies mix in the air and create these harmonics known as intermodulation distortion,” says Ciaudelli. “That’s not what happens. Intermodulation occurs when an active electronic component like a transistor, in an antenna booster or the front end of a receiver, get exposed to two or more signals of sufficient strength that harmonics are generated.”

He continues, “There is a point where information theory requires a certain amount of bandwidth or else you have to make sacrifices in audio quality, latency or range, or all of the above. Probably the most important feature for spectral efficiency is high linearity. That means that radio frequency harmonics—intermodulation products—are never generated. We’re building equipment with higher and higher linearity. That means more expensive components that require higher current draw that could result in lower battery life; all of these things have trade-offs. But you will see that spectral efficiency, packing more mics within a small sliver of available spectrum, will continue to be an important design criterion in professional mics.”

Brunner reports that Shure has similarly been developing more efficient systems while also introducing products for use beyond UHF. “For several years, we have been exploring alternatives, not only to increase spectral efficiency within UHF to allow for more systems to operate in smaller swaths of spectrum or fewer open TV channels, but also to provide options outside the TV band. Our MXW [Microflex Wireless] line, which operates in the DECT spectrum, is a really useful tool for installers, particularly in business, education and other environments. That spectrum is not subject to regulatory change, at least any time in the near future.” Shure offers systems operating in the 900 MHz band (ULX-D, QLX-D and PGX-D) as well as at 2.4 GHz (GLX-D Digital Wireless). In early December 2016, the company announced that it had started shipping its ULX-D Digital Wireless System and related accessories for operation in the VHF frequency band. The QLX-D system will follow suit early next year. The new VHF options offer 42 MHz of tuning bandwidth. He predicts, “For license-eligible operators, the 941 to 960 MHz band is going to become increasingly important.”

Dynamic spectrum access is standard in the Wi-Fi and Bluetooth traffic commonly found in the 2.4 GHz ISM band, says Donovan, and that unpredictability has dissuaded some pro audio operators from considering products in that range. “But Audio-Technica’s System 10 digital wireless, first introduced in 2012, tackled the complexities of the dynamic 2.4 GHz ISM band from its inception,” he says. “System 10 continuously examines the spectrum looking for potential interference and, with its redundant transmissions, shifts to frequencies free from interference without the need for operator intervention.”

The System 10 line has since expanded. Transmitter options include belt pack, hand held, XLR base and boundary microphones, allowing users to replace or augment existing wireless systems. “The System 10 stand-alone products can provide eight simultaneous channels while System 10 Pro can support up to 10 simultaneous systems,” adds Donovan.

Once the auction phase is successfully concluded and the frequency repack details are announced, there will be a maximum of 39 months before the relevant spectrum must be vacated to make way for the new occupants. But it could be sooner than that if the new incumbents are ready to throw the switch and start their test procedures.

Meanwhile, there are several Petitions for Reconsideration of the FCC’s Report & Order documents that need to be concluded. “We eagerly await the outcome of those, because some of those do affect specifications and design requirements for wireless mics going forward,” says Brunner.

Whatever the eventual outcome of the auction and repack, the future for wireless mic operators will involve a potpourri of different frequency bands and a mix of licensed and unlicensed bands, Brunner believes. “It will be about understanding the scale of the job that you’re working on. If an unlicensed band option is suitable then it’s certainly worth considering,” he says.

“Some of this unlicensed spectrum is more limited in terms of how many simultaneous systems can get up on the air and function properly. In many cases, in smaller installations or on campuses where a few mics are being used in different locations, it can certainly be a very viable option, and removes the headache of having to navigate through the transition period and changes to TV that may be happening in your local market.

“I think the important thing for contractors to know, and to have their eyes open to going forward, is that the landscape in their location is going to change over those 39 months. It’s incumbent on wireless mics not only to not interfere with new licensed services in the auction band, but also it may require some new frequency assignments once the dust settles and the new TV map is realized,” says Brunner.

Despite the challenges, Ciaudelli is upbeat about the potential post-auction environment for wireless mic operators. “I wish that we didn’t need to go through this auction, but for those who predicted doom to our industry, that’s just not true. The future holds plenty of wireless microphones.”

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