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Sports Telecasts Drive Wireless Mic Designs

Part of the appeal of watching sports is the varying degrees of contact between participants on the field (or track). And behind the scenes, in the televised coverage of sports, there's another collision setting itself up to happen—it's a supply and demand problem.

On the demand side of things, it's all about spectrum.

"What [sports telecast producers] are looking for is the ability to run more frequencies," said Gordon Moore, vice president for sales at Lectrosonics Inc., the Rio Rancho, N.M., manufacturer of wireless microphone eqipment. "The demand for putting microphones on virtually every player seems to be increasing."

Looming on the supply side horizon is the possible loss of the 700 MHz band for licensed wireless mic operation after the shutdown of analog TV next February.

Sennheiser's latest wireless microphone technology is specifically designed for congested spectrum situations. However, that analog sunset date might be a bandwidth wash. Today many television stations are operating both analog and digital channels. So should the 700 MHz band be lost for licensed wireless mic operation at the analog TV sunset, there could be considerable bandwidth in the 500 and 600 MHz bands abandoned by the analog transmitters and available for licensed wireless operation.

(There's also the possibility that the FCC will rule that licensed wireless mic users will have to move to the proposed GWMS ban—2020-2025 MHz—which is beyond the scope of this article.)


In any case, at crowded broadcast sporting events there continues to be more pressure on wireless mic bandwidth. Fortunately, riding to the rescue are wireless microphone makers.

"Wireless systems that are being produced now have front-end filters [that] are a lot narrower, improved antennas, better sensitivity and selectivity, digital tone squelch, and improved diversity, so it's easier to get multiple frequencies into a certain band," said Dan Montecalvo, marketing manager for installed sound, broadcast and theater at Stow, Ohio-based Audio-Technica U.S. Inc. "A lot of stray frequencies that are on the air, or nearby frequencies, are not going to affect the system." He pointed to Audio-Technica's 4000 and 5000 Series systems, which provide 200 different channels.

"If you move to a different city and the channel from the previous city is not good, you can utilize other frequencies that will work."

Montecalvo said that as these lines incorporate the company's IntelliScan system, the receivers have the ability to flag potential interference issues and take appropriate action.

IntelliScan allows the operator to set up multiple receivers at once. The transmitters are then manually tuned to the receivers' frequencies. Presets allow settings for repeat situations to be retained on both receivers and transmitters.

"These units do a scan and look for problem frequencies, and set your operation away from those problem frequencies," he said. "This feature, plus the design improvements we have been able to implement, will help licensed broadcast users maintain good connectivity despite the crowded spectrum."

Sennheiser Electronic Corp., which has U.S. offices in Old Lyme, Conn., is no stranger to continuing spectrum squeezes and has its own innovation for coping, the newly designed EM 3732 receiver.

"It's a very, very frequency-agile, 90 MHz, switching bandwidth receiver," said Dawn Birr, professional systems product manager at Sennheiser.

"It's really easy to use," she said. "It provides excellent protection from intermodulation [additional signals created when two or more radio transmitters interact with each other]; and suppresses intermodulation more tightly and greater than any receiver we've ever built in the past."

Birr pointed out that the new wireless receiver pairs well with the company's SKM 5200 handheld transmitter microphone.

"If you're in one city, on Saturday, and your Sunday city is a thousand miles away, the SKM 5200 allows you to go in five KHz increments to a frequency that's going to work for you."

Because the SKM 5200 has a number of interchangeable mic capsules, the audio engineer can change the characteristics of the mic to adapt to the particular application it's being used for, or to optimize the voice quality of a particular sideline announcer, according to Birr.


Sony recently introduced their first digital wireless mic system, the DWT-B01 digital wireless transmitter and DWR-S01D dual channel wireless receiver. Karl Kussmaul, pro audio product manager for Sony, pointed to the advantages of a digital wireless mic system.

"Compared to previous analog technologies, digital wireless offers a great improvement in sound quality," he said. "In addition, by using fully digital transmission, it dramatically improves reliability of the transmission. In analog wireless systems, broadcasters are very concerned about—particularly when you're dealing with a live sports broadcast—being able to achieve reliable operation."

An additional feature of the DWR-S01D receiver is that it's a slot-in mount design, engineered to fit the PDW-700 XDCAM-HD422 camcorder slot.

"This allows for a streamlined camera package without having equipment hanging off the camera," Kussmaul said. "Particularly in sports, camera operators like the streamlined packaging because they very quickly have to move around."

In Sony's WL-800 analog receiver line the company also makes slot-in receivers.

Azden Corp, another player in the wireless mic field, and located in Franklin Square, N.Y., provides three different models of its 1200 Series wireless receivers, including the SI model that is designed to slot-in mount into Panasonic and Ikegami camcorders equipped with such mounts. They also have the AB model for mounting between the camcorder and an Anton/Bauer Gold Mount battery, and the VM model for similar mounting with V-mount batteries.

Azden's 1200 Series provides both a body pack and block design. Wayne Alonzo, vice president of sales at Azden describes the XT block design transmitter as "one of those little square transmitter boxes with the XLR connector on it.

"You can use a stick mic with it, you can put shotgun microphones on it, or even a lapel microphone because that particular transmitter will work with dynamic mics, or with any condenser mic," he said. "It will accept anywhere from 12 to 48 volts of power."


Lectrosonics has found a ready customer for its ruggedized SM Series digital hybrid wireless microphone transmitter—NFL Films. "They're looking to keep them as small and light as possible, because they're mounting the SMs in the players' shoulder pads," said Lectrosonic's Moore.

Since it goes without saying that the transmitters have to be rugged enough to withstand the violent blows in a football game, the SM body is carved out of a solid block of aluminum.

Moore also pointed out that for NFL Films' use, the transmitters have to be waterproof, even if it isn't raining on game day.

"Sports seems to bring out the worst in us, from a sweat point of view," he said. "So there's a demand for units that can handle that."

The SM model in its smallest form factor is the SMa. The slightly larger SMDa holds a second battery to double operating time; while the SMQa provides a higher 250 mW output (the other two models produce 100 mW).


Spectrum availabiliy for wireless mic operation is also influenced by two additional factors. One is the growing trend toward providing 5.1 surround sound for live broadcasts. This requires stereo micing with two transmitters and twice the bandwidth requirement.

The second factor is the controversial white space issue. While 100 mW wireless mic transmitters may be able to overpower low power devices operating in white spaces outside the sporting venue, there is the worry that in the future, the venues themselves may employ white space equipment and that could be a problem.