Sign up for ProSoundWeb newsletters
Subscribe today!

Special Report: The State Of Production Audio Wireless
Top RF consultant James Stoffo discusses the picture for wireless system use...
+- Print Email Share RSS RSS

By now, we should all be well aware of the fact that our production audio “RFscape” is changing dramatically due to the introduction of digital consumer devices within the wireless microphone spectrum. The next two years will separate the women from the girls and the men from the boys when it comes to wireless audio operation in the United States.

It’s becoming more and more difficult to operate multiple wireless systems, including microphones, in-ear monitors, IFB, and intercoms, on events and installations. We have overcome the energizing of digital television (DTV), the “700 MHz” auction, and are preparing for the mass introduction of white space devices in the U.S. and around the globe. And the FCC is already speaking of further auctions within what is left of the production audio wireless spectrum.

Though these additional auctions are scheduled for next year, it may be years before they actually take effect. I heard the first mention of digital television in 1991 but it was not fully adopted until 2009. This means that we likely have time to prepare and properly plan. As long as we know what to plan for, I believe that we’ll get through the next wave of electromagnetic assault on our wireless systems relatively unscathed.

Making It Work
Let’s start with what we do know as fact. We’ve been forced to operate all of our wireless audio in about half of the spectrum that we’ve had since 1962. Next year, with the introduction of white space devices en mass, we’ll need to work with less than 10 percent of the UHF spectrum that we’ve always had. The Fixed and Portable digital consumer devices that we’ll be sharing radio spectrum with must follow very strict guidelines.

The two types of white space devices have two distinct sets of rules, so it’s a good idea to understand the differences between them. Fixed devices may operate anywhere in both the VHF and UHF radio spectra; however, they cannot operate adjacent to any local TV station. This means that you may operate wireless microphone and intercom systems adjacent to TV stations when planning for Fixed White Space Devices. 

Portable White Space Devices may only operate above 512 MHz (or TV channel 21) and do not have to obey the adjacent TV channel rule. These will be the “smartphones” in your audience that may really create havoc within wireless systems. The FCC has left the pro audio community with a total of 12 MHz of radio spectrum to operate within, including mics, IEMs, IFBs and intercoms.

The only way to make that work will be to properly band plan. It’s always a good idea to separate base transmitters, such as IEM and intercom transmitters, as far away as possible in terms of frequency from base station receivers, such as wireless mics and intercom receivers. This keeps the overall RF noise floor low and guarantees the best range and audio quality from wireless audio systems.

In addition, find out which specific two 6 MHz slices of spectrum are reserved for wireless systems in the city in which you’re operating. These two TV channels will change from city to city and the information is available to anyone in advance. They will always be the two closest open TV channels above and below TV channel 37. TV channel 37 goes from 608-614 MHz, so this rule will change after the next auction—but will certainly be in effect for the next few years.


Commenting is not available in this weblog entry.