Tech Focus: Wireless Bodypack Transmitters, Part 1 — Battling on Several Fronts

“Better, faster, cheaper — pick two.” That nostrum of technology has proved valid for most verticals in the digital era but not for wireless audio.

“It has to work every time without fail, it has to be high-performance, it has to be affordable, it has to be flexible, it has to be smaller yet even more powerful and with even more features. People expect a lot from wireless systems,” observes Karl Winkler, director of business development, Lectrosonics. That has become even harder to accomplish as the wireless industry faces the second major loss of key RF spectrum in a decade, in the form of an FCC-mandated auction of the 600 MHz band scheduled for 2016. It means that wireless-bodypack manufacturers have to fight on multiple fronts to stay both viable and competitive.

Winkler notes the innovations that his company has had to develop to address market demands. In the face of spectrum loss, Lectrosonics offers bodypacks in three distinct frequency ranges, most out of the 600 MHz band; where the frequency does enter that zone, the device has the capability of locating guard-band and mid-band gaps automatically.

The company’s newest bodypack, the LT, has a multifunction switch that can be a mute button, power switch, or talkback button, depending on the need and the situation. Longer antennas are also thinner, minimizing physical interference with athletes. Power capability of up to 250 mW also includes a circulator/isolator to prevent intermodulation with nearby transmitters, an issue that becomes a bigger problem as RF-spectrum loss pushes noise floors higher.

(Some broadcast users are also asking whether it would be viable down into the VHF range, between 174 and 216 MHz. That would require even longer antennas, which would make them unusable for wireless bodypacks’ other major constituent: theatrical productions.)

Glenn Sanders, president of Zaxcomm, whose bodypacks are used by NFL and NBA teams, says the specter of spectrum loss prompted redesign of the company’s TRX and QRX product lines to widen their bandwidth to between 512 and 600 MHz, offering users more range below 600 MHz while still being ready for the carve-outs, such as guard bands and mid bands, in that piece of spectrum after the auction. The bandwidth range can also be adjusted by the factory, if necessary, for a fee. “We’re trying to keep it as flexible as possible so that not everyone has to run out and buy all new equipment,” he says.

Zaxcomm has also integrated a recording system, using a chip and a micro-SD card, into its bodypack. According to Sanders, sports users find that feature useful for gathering audio where microphones can’t go, and that has been finding its way into postproduction of sports-broadcast packages. A more recent new feature is NeverClip, a patented process for extending the microphone’s dynamic range to 126 dB without significant clipping and without the distortion that processed limiting can induce. “We’re all trying to adapt our products to what’s going on with spectrum,” he notes, adding, “But, at the same time, we have to also keep coming up with ways to differentiate our products.”

Interestingly, the high level of demand for this type of product has kept the number of manufacturers in that sector very steady, with little more than a half dozen able to meet the rigorous requirements of broadcast and theatrical users, the two biggest customer segments. Instead of the Asian competition that other pro-audio sectors have experienced, top-tier wireless manufacturers often find Asian markets their biggest customers. Winkler says his biggest sales have been to Japan.

Costs to Vendors
Spectrum reallocation is also going to cost vendors of bodypacks and related wireless services more money. Michael Mason, president of CP Communications, has seen the cost of wages and time spent on frequency coordination increase as available spectrum is reduced, and he expects that to continue. “The demand for more [wireless] audio in sports, especially on the field, is huge, and it’s driving the need for more frequency-coordination efforts,” he says. “It gets more difficult to use wireless every year, week to week. It means we have to hire more people to do coordination.”

He notes that wireless assets are already spread thin in broadcast sports, given the demand for more sound from more sources. That was underscored by a snowstorm that blanketed the Midwest and Northeast with several feet of snow in November and caused relocation of an NFL game from Buffalo to Detroit and an ensuing scramble to get wireless assets repositioned. “At the same time,” he adds, “we had another remote unit heading to New England that almost didn’t make it due to weather.”

The wireless assets allocated for each game are specific to the conditions at each game’s location: available frequencies and channels, overall RF density, types of equipment on each truck. Changing them at the last minute is extremely challenging, if not impossible, depending on the circumstances, says Mason.

At a time when sports viewers are demanding more on-field audio than ever, wireless bodypacks — the gateway to collecting that sound — are facing their biggest technical and economic challenges ever. This playbook is still being written.

Click here for Tech Focus: Wireless Bodypack Transmitters, Part 2.