At most sporting events, wireless microphones have become about as ubiquitous as beer and foam fingers. They're used to allow for communications involving everyone from coaches and quarterbacks to pit crews and play-by-play men.
But the introduction of communications devices that operate using so-called "white space" could threaten the ability of those wireless networks to operate flawlessly, sports leagues and broadcasters said last week. The NFL and ESPN, in particular, have called for real-world testing of the new devices at live games as soon as this summer.
The Federal Communications Commission is examining several communications devices that would operate using the available spectrum typically used by over-the-air television. The spectrum, known as "white space," is generally seen as underused and could be used for wireless Internet or portable television service.
Google, Microsoft and other major technology companies are developing devices that would work using white space, and they claim the devices would not need to be licensed or coordinated.
But sports leagues and broadcasters said they would like to see evidence showing the devices will not interfere with their own wireless microphones, which use the same spectrum.
"We just think they have to prove these devices don't interfere," said Ken Kerschbaumer, executive director of the Sports Video Group - a trade group that promotes the distribution of sports content. "You can't just go on promises."
The NFL and ESPN last week wrote a letter to the FCC requesting "real world" testing at FedEx Field in Landover and M&T Bank Stadium in Baltimore.
The FCC performs its own field tests but has not committed to examining how the devices work during games.
"We received the invitation and will consider it," FCC spokesman Robert Kenny said. "We certainly remain optimistic that the field testing will start well before the NFL season."
The use of wireless microphones at sporting events requires heavy amounts of coordination. A prime-time NFL game, for example, requires 135 wireless microphones, and all must be registered on specific frequencies to ensure there is no interference.
The FCC's Office of Engineering and Technology last year reported tests of white space devices had trouble sensing so-called "incumbent" users of the space. But since then, several companies, including Microsoft and Phillips, have disputed the test results and have continued to work on prototype devices, claiming they can operate without interference.
A coalition of the companies has proposed a beacon system that would alert devices about occupied spectrum. But sports groups cautioned that the beacon system remained unproved.
"If the devices are unlicensed and uncoordinated and there's interference, then there's no recourse, no one to go to," said Jeff Willis, coordinating technical manager for ESPN Productions.