FCC R&O Addresses Spectrum Changes for Wireless Mics

By Steve Harvey, SVG Contributor

With the release on June 2 of the FCC’s Incentive Auction Report and Order (R&O), following the May 15 vote — a 3-2 decision along party lines — the long-term future looks to be full of potential changes and challenges for users of wireless microphones and in-ear monitors.

Says Roger Charlesworth, executive director, DTV Audio Group, “It’s going to be as problematic as we thought it could be. It’s still several years away, but, after the TV-channel repack, it will become virtually impossible to do large-scale production in the 600 MHz band.”

In summary, with regard to wireless microphones, the R&O permits exclusive licensed operation by broadcast and cable entities — a concession aimed at ENG crews — in what is likely to be just 4 MHz of the 11-MHz–wide duplex gap that will separate the uplink and downlink spectrum. It also permits unlicensed operation by all users, including consumer devices, in the guard bands and in what is described as “one naturally occurring white-space channel in the remaining TV band in each area” and unlicensed operation on channel 37 “at locations where it is not in use by channel 37 incumbents, subject to the development of technical rules to prevent harmful interference to the incumbents.”

The Incentive Auction’s 600 MHz Band Plan will strip away the two TV channels that are currently reserved for wireless-microphone use. Even this 12 MHz is by itself completely inadequate for large sports and entertainment events, which routinely use 100 to 150 wireless frequencies, says Charlesworth. “That’s more like 10 TV channels. Theoretically, there will be one naturally occurring channel available to be shared with white-space devices after the channel repack, but I think that’s a fantasy. Over the long term, there really won’t be a useful amount of spectrum available.”

An interesting aspect of the R&O is the relaxing of co-channel–operation rules for wireless mics. In reality, the impact of this may be negligible, as large-scale productions already bend the rules to fit in microphone frequencies where they can. “The truth is, co-channel operation is already a fact of life, and, going forward, there will be a whole lot less space to do it in. If you are running, say, a major studio complex with 500-plus mic channels, you need every trick in the book to make it work. After the repack, you are going to need a plan B.”

If there is any good news, it is the expansion of eligibility for Part 74 licensing — and, thus, protection from unlicensed white-space devices through the TV-bands–database registration system. An accompanying R&O amends Part 74 Rules to include professional sound companies and venues that routinely use at least 50 wireless microphones.

“This is long overdue,” says Charlesworth, “and is of enormous value to Broadway shows and tours, bands and sound companies, and equipment-rental houses.”

With the demand for mobile data showing no sign of abating any time soon, what remains unclear from the R&O is where wireless microphones will be able to operate in the future. The good news is that the R&O specifically commits to initiating proceedings to find additional spectrum for wireless-microphone users.

To this end, manufacturers and users in the DTV Audio Group have engaged in productive discussions with the FCC’s Office of Engineering and Technology about potential frequency-spectrum and wireless technologies that could be used in the future.

Charlesworth reports that a number of bands that could be shared by professional users are being considered and there is some support for harmonizing with Europe where products are already in use. In addition, some bands requiring longer-term development of new products at more-difficult frequencies are being discussed along with changes in rule-making around new technologies, such as ultra-wideband (UWB) transmission.

Television stations that give up their spectrum will have three years after the three-month filing deadline to make the transition to their new channels. Spectrum in the 600 MHz band could therefore remain available to RF mic operators for as long as 39 months after the auction. Added to the fact that the auction is slated for early 2015 and may be further delayed by legal challenges, this suggests that the current technology will likely remain useful for many years to come. In the meantime, it is hoped that the FCC will move quickly enough on new spectrum to allow manufacturers to develop new product and technologies in time.

A position clearly stated by the FCC in the R&O is that new digital technologies are expected to play a part in long-term solutions for wireless mics. This doesn’t give much recognition to the incredible performance demands put on today’s professional mics and related devices.

Ultimately, says Charlesworth, the loss of UHF spectrum will have the greatest impact on any artist with a hand mic and in-ear monitor trying to hear themselves in stereo and high fidelity with low latency. “That’s where it’s still going to be very hard to replace FM transmitters and receivers operating in clean UHF spectrum.”