Shrinking Spectrum Impacts Intercom Operations

Smartphones and football aren’t mixing well. That’s what wireless-communications specialists have been finding in the past year, the first full one after the FCC’s massive spectrum reallocations, which smartphones and WiFi-enabled tablets bumping up against wireless intercoms inside stadiums.

The hot spots set up to run wireless intercom systems appear to be on, and the phones try to connect to them, according to Andy Cocallas, owner of Game Time Communications, an RTS/Telex dealer. The wireless-intercom consultant has worked on intercoms at all 32 NFL stadiums, including regularly for his hometown NFL Chicago Bears, as well as college and high school football.

Although these phones can’t connect because of password protections, he notes, the onslaught of thousands of Verizon and AT&T phones simultaneously pinging the broadcasters’, leagues’, teams’, and schools’ intercom systems creates invisible mayhem across the 2.4 GHz band and causes signal dropouts.

As a result, says Cocallas, many network broadcasters and leagues continue to use the more expensive UHF band for wireless-intercom applications. In fact, many prefer it for its better audio quality, fewer dropouts, and familiarity. He notes that it’s all he uses for his work with NFL teams but the pain is being felt more by colleges and high schools, for which WiFi-based systems are more affordable.

“The problems with this really started being felt in the last year or so, between tighter spectrum and more and more smartphones being present and used in football stadiums,” he says. “Plus, while UHF might be costlier to use, at least it’s regulated, which can give you more confidence. With WiFi, there’s no sheriff out there; you can wind up with havoc.”

Programming-Based Development
The only way to help WiFi get more traction in the intercoms category, Cocallas maintains, is for the manufacturers’ engineers to find programming-based solutions to the onslaught of wireless consumer devices.

According to John Kruman, industry solutions engineer for government and mobile productions for the U.S. arm of Germany-based Riedel Communications, spectrum volatility and vulnerability are ongoing concerns for broadcasters and leagues alike. Riedel has tweaked its wireless products in the past year, for instance, by enhancing its MediorNet network system with directional antennas that its Acrobat intercom system can ride; its most recent installation is at the Pittsburgh Penguins’ CONSOL Energy Center arena.

He says that more far-reaching solutions will have to include other types of technologies, such as the Audio Video Bridging (AVB) set of technical standards that provide the specifications for time-synchronized low-latency streaming services through IEEE 802 networks. Riedel, one of several audio companies in the AVnu Alliance, an AVB trade group, emphasizes that its intercom system has 100% digital operation.

Conflicts With Consumer Devices
The current biggest challenge, Kruman believes, is fighting for spectrum allocation in severely narrowed channels in the dedicated operational band known as DECT (digital enhanced cordless telecommunications), with consumer-device activity on either side of its 192- to 193-GHz–frequency allocation, which he says is still less volatile than the public/open 2.4 GHz bands that other wireless intercoms are tuned to. (“At least, until they sell that off, too,” he adds, darkly.) It’s a situation that he says will be exacerbated in more wireless-dense environments: “Next year’s [2014] Super Bowl will be the first one in New York, and that New York-New Jersey border area is a frequency-allocation nightmare.”

Clear-Com Product Marketing Manager Vinnie Macri says his company’s Tempest 2.4 GHz wireless system encounters many of the same frequency-allocation issues, which is why he also expects that UHF-based solutions will continue to be the first choice for most major broadcasters. A frequency-hopping capability gives the Tempest system some nimbleness in particularly dense RF environments, and Clear-Com also offers a 900 MHz system, which offers another slice of spectrum when the 2.4 GHz band is too crowded.

He says the company is putting equal emphasis on its newer HelixNet wired party-line system, which has been demonstrated in recent months in several high-profile football games and extreme sports and is intended to replace analog beltpack applications. The system is IP-based, able to run on an Ethernet VPN. Macri says that the HelixNet’s 12 kHz bandwidth offers better audio quality and is immune to such analog problems as ground noise and that IP-based distribution and transport offer a high degree of reliability. However, he also concedes that the deeply entrenched analog infrastructure in trucks around analog party lines will take some time to breach.

Jess Heimlich, owner of Digital Communication Systems in Las Vegas, a wireless-communications guru who provides those services for large-scale events, including the X Games and the Super Bowl, agrees that shrinking spectrum is a continuing problem, especially for intercoms. He believes that’s driving development of WiFi and VoIP solutions.

“The Big Three — Telex, Riedel, and Clear-Com — have made giant strides in perfecting VoIP; I don’t think I could do a large, multitruck event without it,” he says, citing his use of the HelixNet system. “Trunking of remote venues and mobile units relies almost entirely on VoIP, and WiFi is also becoming a major player in communications.”

A Problem With Power
However, Heimlich adds, WiFi is inherently limited when it comes to power — most WiFi devices transmit at about a tenth of a watt — and antenna-systems coverage, which generally requires line-of-sight between devices. Increasing the power of each wireless access point could overload a wireless system, so the best solution currently is to use multiple points at lower power, he says, cautioning that maintaining precise power levels and placement is difficult in environments like stadiums, which means that manufacturers will likely put more emphasis on high-gain antennas in the future. Putting intercoms on WiFi is viable but requires, he says, a delicately balanced wireless ecosystem.

Spectrum reallocation continues to engender uncertainty when it comes to professional systems’ wireless operations, even as intercoms are looking at developing pathways using both WiFi and Ethernet/IP. Manufacturers, though, don’t seem to be waiting for the dust to settle around frequency allocation: new intercom products continue to hit the market, with several expected to debut at the NAB Show in April.

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