Intercom Systems Face Wireless Challenges With Spectrum Losses

Observations often heard from intercom-frequency managers these days lament the ongoing loss of spectrum to federal RF auctions and also express concern at the growing number of crewmembers who warrant their own wireless beltpacks. Unfortunately, those two concerns are diametrically opposed.

“Guess what. You can’t have it all,” says Henry Cohen, senior RF design engineer and project manager at CP Communications. He adds that continually contracting spectrum will compel event producers, including broadcast sports, to make decisions about how to deploy wireless systems, and intercoms, which take up the lion’s share of RF channels on live sports shows, will be significantly impacted.

“You’re not going to have 400 people on wireless beltpacks on a single production anymore,” he says. “We’re going to have to go back to area miking and concealed-wired-microphone techniques that we used years ago. We’re not going to stop having big events, but the nature of those events is going to change. Instead of the reporter with the wireless microphone going to the MVP after the game, they’ll have [the MVP] go to a podium where a wired microphone will be waiting.”

Intercoms have a well-defined graphical matrix. If you split the chart into digital and analog, wired and wireless, we see wired systems moving rapidly into the digital quadrant and wireless systems trying to do the same but remaining very much anchored to analog. Cohen says digital wired systems offer far more scalability of flexibility of configuration, helping overcome the inherent problems associated with running a lot of cables across a sprawling event campus.

However, wireless remains crucial for most sports broadcasts, and that’s sparking a search for alternatives to the audio sweet spot of the mid-UHF bands, including use of remaining lower-frequency UHF bands and higher frequencies in the gigahertz range.

Among solutions discussed at the recent DTV Audio Group meeting during last month’s SVG Summit were moving far up the spectrum ladder into the 6 GHz range and even the possible use of infrared, which would require line-of-sight wireless connections, a difficult thing to predictably achieve in live sports.

New solutions require innovative technology but also have to battle some preconceived notions. Vinnie Macri, product marketing manager at intercom manufacturer Clear-Com, notes that his company’s Tempest 2.4 wireless system is digital and operates within the 11-channel 2.4 GHz range — the one occupied by WiFi, Bluetooth, and other consumer electronics devices — which he acknowledges makes some users nervous. The system uses an agile, frequency-hopping technology that constantly moves the signal around, using no channel for more than 200 ms, thus avoiding interference.

Still, he says, the NFL and other leagues have refused to allow 2.4 GHz systems to be used in their venues, as the leagues develop their own in-stadium WiFi applications to boost attendance. But the idea is gaining traction: Macri says more rental companies that support broadcast sports are acquiring these systems.

“There are avenues of possible solutions out there, but each one has its drawbacks,” he explains, noting the shorter effective distance and lower penetration of higher frequencies.

Larry LaFave, VP of remote operations and engineering at CBS Sports, says that, while spectrum reallocation is prompting a lot of innovative thinking, it appears increasingly that there will not be a single industry-wide solution, as UHF has been for decades. This, he says, is problematic for the broadcast industry and even more so for the rental vendors that provide the majority of wireless microphones used in network sports broadcasts. “The onus is really on them,” he says, “because they provide us with what we need in that department as our requirements change seasonally.”

Andy Cocallas, owner of Game Time Communications, who has worked on intercoms at all 32 NFL stadiums (including regularly for his hometown Chicago Bears), as well as for college and high school football, has been one of several wireless intercom consultants beta-testing various solution from several companies. He credits them for diligence but says he hasn’t encountered what he considers a universal fix yet, which makes him anxious as more consumer television-band devices (TVBDs) move into the market. He’s continuing to rely on existing products made for the UHF band, such as the RTS/Telex BTR-800, but says, as UHF availability shrinks, “It’s getting harder to use what we still have. The problem is, we just don’t know what’s coming next.”