Having been chased out of the 700 MHz band some years ago by the advent of DTV broadcasting, and now having to make way for the new telecom licensees in the 600 MHz band as they begin their services, equipment providers and frequency coordinators for major events are faced with a spectrum crunch. Now, and in the foreseeable future, that means that RF professionals will most likely need to deploy a patchwork of wireless microphone and in-ear solutions at large-scale sports, entertainment and other events—and that goes double for wireless intercoms.
Comms frequencies far outnumber the wireless mic and in-ear channels at major events like the Super Bowl and televised awards shows—events that employ Gary Trenda, an RF technician with Orlando, FL-based Professional Wireless Systems. But while wireless mic and IEM setups are typically operated in the so-called beachfront property of the low-band UHF spectrum, comms products have increasingly moved up the spectrum.
Trenda was the lead RF intercom technician this year for the Latin Grammy Awards, held at the Grand Garden Arena at the MGM Grand Hotel & Casino in Las Vegas. He says, “We had three—four, if you count the red carpet—different intercom systems. We had close to 80 users on wireless intercoms. To get that many people on a wireless intercom system, you reach the limitations of the various systems.” With the available UHF TV channel bandwidth shrinking, he comments, “People are looking for where else they can locate these systems.”
For example, he says, Clear-Com’s FreeSpeak II system, which operates in the license-free 1.9 GHz DECT band, maxes out at about 25 people. It is also available in a version that operates on the 2.4 GHz ISM band (which is also occupied by Wi-Fi) that supports a larger number of users. Riedel’s Bolero can handle 50 users, but there are some practical limitations, says Trenda. At the Latin Grammys, PWS also used a Radio Active Design (RAD) system, which utilizes both UHF and VHF, and some older Telex BTR 800 UHF systems, he reports.
Related: PWS Keeps Latin Grammy Awards’ RF A-OK, Pro Sound News, Dec. 12, 2017
“To get enough people onto wireless intercom, you’re using a variety of different systems,” he says. “We could put, let’s say, 28 people on RADs and another 25 people on FreeSpeaks, then some on Telex BTRs.”
Going into an event, there are several things to consider, says Trenda. For instance, “We’re trying to cover a wider area than you typically would with microphones and ear monitors. A lot of the wireless intercom coverage needs to be a good chunk of the entire venue in which the show is happening.”
Not all systems work the same, either. “The coverage requirements for setting up antennas for a RAD system, with UHF and VHF antennas, is very different than, for example, a Clear-Com FreeSpeak, where the antennas are essentially a Cat 5 connection—but you only get five users connected to each individual antenna, so you end up building a small cellular telephone-style distribution system all around a venue.”
Related: Wisycom Provides Flawless RF Coverage for New Year’s Eve Event in Times Square, Pro Sound News, Jan. 16, 2018
At a recent show, Trenda had two technicians for an entire day just running antennas. “We put up over a dozen antennas all around the American Airlines Center in Miami. You’re talking about one full load-in day just for antennas and cabling.”
Operators need to select a system that best meets a specific application—in addition to spectral efficiency, of course. “There are certain restrictions to what you can do in the 1.9 MHz DECT band versus what you are doing in 2.4 GHz, which is an ISM band,” he says. The RAD system uses AM, while DECT equipment communicates between the beltpack and base station digitally; the respective propagation characteristics need to be considered.
“Our challenge as technicians is knowing how to make these systems all work well and get the coverage that we need with the number of users that these shows are asking for.”—Gary Trenda
In the future, operators will need to use a variety of products and solutions appropriate to each application, and it’s entirely possible that a touring production might need to travel with multiple solutions to handle variable conditions. “If you were thinking of using a Pliant or a Tempest wireless intercom system that operates in 900 MHz ISM, that works very well in some venues, but it may not be the best solution in others,” says Trenda.
One of the larger challenges, he says, is building these different systems, which all operate differently, into a cohesive setup that works reliably and can offer access to everyone who needs it. “If you already own a Clear-Com matrix frame, the way that a FreeSpeak intercom will integrate into that matrix frame is different than how a Riedel Bolero integrates with their own matrix frame, versus tying a Clear-Com system in with, say, an RTS system,” he says.
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“Our challenge as technicians is knowing how to make these systems all work well and get the coverage that we need with the number of users that these shows are asking for. I enjoy the challenge of it,” he says. “It’s been fun to see all of the changes that have happened with the different intercom systems.”
Professional Wireless Systems • professionalwireless.com