FCC issues final ruling on wireless audio gear and UHF “White Spaces,” and what it means for your theatre

[A version of this article appeared in the October edition of FOH magazine, a sister publication to Stage Directions—but just because it was written for roadies, don’t hold it against the reporting. The coming changes in wireless microphones will have far-reaching effects on the theatre world, and you need to know what’s coming and how it will affect you.—ed.]

On Thursday, Sept 23, the FCC handed down its final decision on what devices will be allowed in the remaining UHF space in the 500 and 600 MHz ranges. All wireless mics, instrument packs and in-ear monitors (IEMs) under 50 milliwatts are still legal without a license under Part 15 of the FCC code. There are commercial systems capable of much higher power, and those still require a license.

Furthermore, the FCC agreed to put aside two UHF TV channels of bandwidth in every city specifically for wireless mics. It appears that these spaces may change slightly from city to city based on what spectrum is currently being used there. The FCC order says these channels must be the closest available to channel 37, which is reserved for radio telescopes.

A UHF TV “channel” consists of about 6 MHz of bandwidth. And two of those are reserved in each city. Using current analog technology, we can squeeze 12-16 channels of wireless into that space. That’s for the total space provided by both channels. Remember, stereo IEMs take about 40% more bandwidth, so probably 10 IEMs max. In a large show, or a venue with multiple shows, that bandwidth will go away fast.

New devices operating in the UHF will periodically have to query a geo-location database that lists pre-existing spectrum users, but a lot of wireless mic users (small theatres) will probably not be included in the database.

Accept Interference
Any wireless user, licensed or not, can operate in the newly designated spectrum—churches, news crews, hotels, schools, oh, and theatre. But part of the regulatory condition of being bound by the rules of Part 15 is that users also have to accept interference from any other device approved to operate under Part 15 rules. If your show and the one next door are stepping one each other’s wireless, there is no one for you to go to and get them to intervene on your behalf.

Additionally, while most pro wireless units give you 100 or more frequencies from which to choose, they are between a set pair of upper and lower frequencies. For example: A wireless transmitter offers 100 frequency choices, but all of those choices lie between 614 and 647 MHz. If, as expected, the protected channels are 36 and 38 then the bands it can legally use are between 600 and 607 mHz and between 615 and 621 mHz. So this unit can use the upper part of the protected spectrum, but more than four-fifths of the frequencies this unit can use lie outside that protected spectrum. The unit will still operate above 621 mHz, but it is an “at your own risk” action.

Bottom Line... For Now
For the official response on the ruling from a number of manufacturers, keep reading. Current approaches from the two biggest wireless makers (Sennheiser and Shure) include slicing the available bandwidth into smaller chunks and working to minimize intermodulation distortion, as well as offering units with much larger bandwidth in terms of available frequencies—in some cases, units that cover the entire UHF spectrum.
So where do we end up for now? The devices that will eventually cause us problems are not even on the market yet. But if I may indulge in a little conjecture… I fully expect to see first-generation versions at the Consumer Electronics Show in January and to see them in use by, probably, April of 2011. The folks who make them are telling the FCC they will be on the market in 2012. Anything they come up with will have to go through a pretty rigorous FCC approval process, so that later estimate might be right. But I, for one, am not waiting around to find out. We have the two channels that have been set aside, and the spectrum between channels 14 and 21 will remain off-limits to these devices as well, although we will still have to wedge our way into the holes in that space. So the sky is not falling today. There are a lot of smart people developing products in this industry, and ways will be found around this. But for now? Hang on, it’s gonna be a rough ride.

We asked all of the major wireless makers and a couple Stage Directions advisors for comment—not spin — following the latest FCC ruling. Here are a few of their answers.

Jason Pritchard
Head of Audio on LOVE
Cirque du Soleil
I am encouraged by the FCC’s latest rulings.  The waters ahead are still a bit murky, but this latest bit of information gives the manufacturers on which we rely a clearer direction in which to develop products for the future. The transition to the future will require technological innovation, agility and adaptation. Theatre won’t go backwards. Audiences continually demand more and more from the performances they patronize, and continuing to deliver the next big thing will be our challenge.

New York and Las Vegas theatres, and other large productions that operate outside of Part 74 of the FCC code, are specifically mentioned and, for the first time, provided for. Large productions will be able to be included in the database that Television Band Devices will have to query before they operate. The process of getting registered sounds like it may be a bit tedious, but at least there are the beginnings of a path to compliance where one previously had not existed.

Jackie Green
VP, R&D and Engineering
Audio Technica
Audio-Technica products are technically well-positioned to operate in the environment defined September 23 by the FCC’s R&O. We have products that operate in the VHF range, we have products that operate below Channel 21, and we have products that operate in the two reserved band ranges. We have products that work well when many simultaneous channels are needed, and we have products that operate well even when used in channels adjacent to TV.

Audio-Technica has always maintained a commitment to continuous improvement and reliability of wireless microphones in the increasingly crowded RF environment, and the FCC R&O has opened the door to our future investment in technical development by making it clear that wireless microphones are here to stay.
Audio-Technica is uniquely positioned as a wireless company going into this new spectrum era. We vacated the 700MHz band more than eight years ago, we have products that work in the lower bands, and we have exciting new SpectraPulse UWB digital technology that operates entirely outside the broadband and TV Band Devices (TVBD)-white space area. We have proven our ability to look ahead to give our customers reliable products, and we look forward to increasing these efforts now that the FCC has recognized wireless microphones and opened the door to opportunity.

Greg Stevens
Owner
Audiovend Wireless Systems
Moving forward, theatres need to realize that wireless microphones are secondary users in the larger electronics landscape, and that the rules and landscape of their wireless are subject to change. It’s not a “set it up one time and leave it” situation. Wireless will require constant maintenance. They’ll need to do their frequency coordination homework and be very thorough, paying particular attention to the FCC rule changes. Oh! And if Joseph’s dream coat has metal fibers in it, remember to mount the transmitter outside the coat!

Karl Winkler
Director of Business Development
Lectrosonics, Inc.
Lectrosonics wireless equipment has always been well-regarded by working professionals who have to “make it work” in very tough RF environments, even when high channel counts of 60+ channels are required. A combination of high-power transmitters (50 to 250 mW), transmitter filtering, receivers with robust front-ends and Digital Hybrid Wireless technology gives these products an edge for such challenging applications. As the RF noise floor continues to rise, these same technical factors will prove even more valuable to users in the future. Lectrosonics was one of the first manufacturers with a pure digital system for professionals (the data-encrypted 700 Series) and continues to invest heavily in R&D for future digital transmission platforms for the standard UHF band and also in other parts of the RF spectrum. Products like the D4 multi-channel digital wireless system in the 902-928 MHz ISM band have already been successfully adopted for TV and film production and for live sound applications.

Joe Ciaudelli
Director of Market Development & Education
Sennheiser
In their commentary, the FCC stated that wireless mic technology is spectrally inefficient. However, Sennheiser has made significant progress in this area with the recent introduction of its new SK5200 II and SK5212 II transmitters. These devices are able to operate in a low intermodulation mode, allowing more mics to be packed in a smaller range.

Sennheiser will continue to innovate; nevertheless, we believe the FCC may not yet fully appreciate the technical hurdles required to increase efficiency without sacrificing performance. Wireless mics must be compact, operate without drop outs, exhibit negligible latency, and have full audio frequency response. No other technology comes close to meeting these performance requirements, and we will continue to communicate these points with the FCC.

The bottom line is that wireless microphones will remain as vital tools in audio systems. Sennheiser will continue to manufacture reliable equipment as well as provide top-level support. This includes its on-line tools (frequency finder and quick reference TV channel charts), its Sound Academy educational seminars, and its expanded menu of RF services.

Chris Lyons
Manager, Technical
& Educational Communications
Shure Inc.
The UHF TV band is gradually becoming more crowded, and many VHF DTV stations are migrating to the UHF band to improve signal coverage. In any given city, the open TV channels are now typically scattered throughout the band rather than clustered together. At events where large numbers of wireless systems are deployed, sound engineers need to be able to take advantage of available spectrum throughout the entire UHF band.

In Shure’s popular UHF-R, ULX, and SLX wireless systems, we increased the number of available frequency ranges, in some cases covering the entire U.S. UHF TV band. In addition, Shure designed the UHF-R wireless system with a wide 60 MHz tuning bandwidth so that the system can roam wide in search of clear frequencies. And Wireless Workbench 5 software makes coordinating and deploying frequencies across multiple bands easier than ever. Together these give sound engineers maximum flexibility to utilize clear spectrum wherever it may be.