Wireless microphones used to be like refrigerators: humming along quietly year after year with no attention other than a fresh battery every week or so. But over the past few years, wireless microphones have become more like computers and software—things that periodically need to be upgraded or replaced due to changing regulations, technical advances, or market conditions.
It's our own fault, really. Americans have been gobbling up smartphones, tablet computers, and other portable devices that access email, music, and video on the go at an incredible rate. These modern marvels need two things to work: battery power and access to wireless spectrum.
For the last several years, the FCC has been aggressively seeking sections of spectrum that aren't being fully utilized, and that can be used—either exclusively or on a shared basis—to help satisfy the growing need for wireless broadband. For data-intensive portable devices, the sweet spot is the range between 300 MHz and 3 GHz, because those frequencies combine good penetration of walls and foliage with short antenna lengths that are practical for a handheld device.
The FCC identified some likely candidates right away. Some of these frequency ranges had been reserved for government use, while others were designated for commercial wireless services that never took off. One section of spectrum that offers significant potential for greater use is the UHF TV band, where the vast majority of wireless microphones and in-ear monitors operate.
At the same time that spectrum allocations continue to evolve, wireless microphone manufacturers are introducing new models that allow more wireless systems to operate in less spectrum, that have better resistance to RF interference, or that can change frequencies when interference occurs—all without sacrificing sound quality.
All of this points to a wireless landscape that will continue to change. Spectrum reform will never be “done,” and the products and techniques that are necessary to deliver professional results will also keep changing. This means that houses of worship that are serious about audio need at least one person on staff who is not only technically savvy, but willing to keep up with changes in both local spectrum conditions and federal regulations.
Consider this your wake-up call: your church needs a wireless nerd. But if you don't have one, here's a rundown of where we've been, where we are, and where we might be headed in terms of wireless microphone spectrum.
WHAT'S ALREADY HAPPENED
The first step that the FCC took to make more spectrum available for wireless broadband was the reallocation of the 700 MHz band (698-806 MHz) to wireless service providers and public safety agencies. The TV stations in this band were moved to lower channels (below 52), and wireless mic users were prohibited from operating in this frequency range after June 12, 2010. If you don't know what frequencies your wireless systems are on, you need to check. If you're still using systems in the 700 MHz band, you could be fined by the FCC, and you might be interfering with the same police, fire, or rescue personnel who would respond to an emergency at your church.
WHAT'S HAPPENING NOW
Step two of the “more-spectrum-for-broadband” process is to allow new types of wireless devices to use the unassigned channels in the TV band. The first of the so-called “TV Band Devices” to arrive were commercial wireless devices, like traffic monitoring cameras and smart utility meters, but “personal/portable” devices such as next-generation smartphones will likely follow in a year or two. When these devices eventually start showing up in pockets and purses in your pews, they could interfere with your wireless microphones and in-ear monitors.
To prevent this from happening, the FCC has reserved two TV channels (a total of 12 MHz of spectrum) in each city for exclusive use by wireless microphones and other professional wireless audio equipment. The reserved channels are off-limits to TV Band Devices, so you won't have to worry about interference.
These channels will vary from city to city, and may even vary in different parts of a large metropolitan area depending on the shape of local TV station coverage patterns. You can quickly find out which channels are reserved at your church's exact location by checking one of the FCC-approved databases that tell TV Band Devices which TV channels are safe to use. (See the “Resources” section for more information.)
The number of wireless mics that can fit into the two reserved TV channels depends largely on how closely together their frequencies can be spaced without interfering with each other. More expensive models typically can use more closely spaced frequencies, so more mics can fit in a limited amount of spectrum. With the two reserved TV channels, you might have enough room for six to eight entry-level wireless mics or as many as 30 top-of-the-line models (and that number is growing every year). That's enough to meet the needs of most houses of worship, even when wireless mics and in-ear monitors for a music group are included.
If the amount of wireless gear you use regularly exceeds these numbers, or you're planning a special event that will require additional wireless mics that won't fit into the two reserved TV channels, you can ask the FCC to clear additional TV channels for a limited time period, within a short radius around your location. You'll need to apply to the FCC at least 30 days in advance, let them know that you're already using at least six wireless mics in each of the two reserved TV channels, and tell them which additional TV channels you want to use. You can request protected channels for recurring events up to a year in advance. Then the FCC will approve your facility being temporarily placed in the database of TV stations and other licensed users that the TV Band Devices must steer clear of. The application process will be finalized later this year.
WHAT MIGHT HAPPEN NEXT
In addition to providing free access to spectrum on unassigned TV channels, the FCC wants to allocate additional blocks of spectrum to wireless broadband carriers, who would pay for licenses to use the spectrum. As outlined in the 2010 National Broadband Plan, some would come from underutilized spectrum currently assigned to government agencies or other commercial services, and some would come from the TV band.
To clear a section of the TV band, the FCC will ask TV stations to voluntarily change channels or share channels (a process called “repacking” the TV band) in exchange for a share of the proceeds when the spectrum is auctioned to wireless service providers. How much spectrum is eventually auctioned depends on how many stations volunteer to participate. The FCC has until 2022 to conduct the auction, so it may be quite a while before we know which section of the TV band might be auctioned.
The landscape of available spectrum for your wireless microphone systems has been years in the making and will continue to evolve for years to come. Now is a good time to take a close look at your equipment inventory, audio staff, special event calendar, and growth plans to make sure that your facility has the right tools to ensure trouble-free wireless operation in the future. Having one person assigned to keep up with wireless rules, spectrum conditions, and product technology will help you to stay ahead of the curve.
Resources
The following FCC-approved TV Band Device Databases provide an easy way to verify which TV channels are reserved for wireless microphone use at a particular location:
SpectrumBridge database:
http://whitespaces.spectrumbridge.com/whitespaces/
Telcordia database:
