Tech Focus: Bodypacks, Part 1 - Wireless Transmitters Are Integral to Sports Audio's Future COVID, encryption, and spectrum pose continuing challenges By Dan Daley, Audio Editor Thursday, January 7, 2021 - 10:04 am
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Today's wireless bodypack transmitters are almost nano-small, their battery endurance is reaching Tesla-envy levels, and the RF spectrum disruptions of the past few years have (mostly) settled down. However, that doesn't mean that their designers and manufacturers don't face other challenges.
Among the continuing challenges is the COVID-19 pandemic, which has made A2s' task of miking athletes a fairly fraught proposition; purveyors of wireless products and services in general have spent vast amounts of time and effort developing and sharing best practices and protocols related to wiring people and things for remote audio during the pandemic. Digital encryption and adjustment to the spectrum repack also confront vendors.
COVID was everywhere that [lavalier microphones] are used, notes Karl Winkler, VP, sales and marketing, Lectrosonics. Early on in this adventure,' we put together materials about using and sanitizing lavs on our website. It quickly became the most popular page on it.
Keeping Secrets Encryption of digital signals has become a significant issue in wireless communications particularly in sports, where coaches and athletes need to discuss strategy and tactics on the field and broadcasters want to get some of that backstage dialog on-air. Winkler says encryption offers various levels, denoted as keys, to sports customers according to the nature of what's being communicated. The most secure keys allow only voice exchanges between devices, such as microphones on beltpacks and cameras, that share an encryption key.
But that information has various uses, he points out. For instance, between an NFL coach and quarterback, the signals have to be fully encrypted to avoid disclosing tactical information ahead of critical plays. On the other hand, an NBA coach's bodypack transmitter is there to pick up the same sorts of tactical disclosures, but they won't be broadcast until after a play is over, when they're heard on-air as part of a replay. That latter application is often the more difficult one to get cooperation for, notes Winkler.
Not every head coach is completely comfortable with this yet, he explains, adding that his company's newest digital wireless system, the D Squared, was recently expanded to four encryption keys. Some [coaches] have to be reminded to turn the bodypack transmitter on. They've been using that audio in the NBA only for the last couple of years, and not everyone is completely sure about how secure encryption is. But that's understandable, given how high the stakes are around that information.
Spectrum Matters Although issues around RF have largely settled down since the end of the 600 MHz incentive spectrum auction in 2017, with the repack going largely into effect through July this year, wireless designers have had to make some adjustments. For instance, Winkler cites standards body ETSI's update in which the deviation - the maximum FM modulation of the nominal carrier frequency - of all new wireless microphone transmitters was changed to a maximum of 50 kHz from the previous 70 kHz.
We know what spectrum we have to work with now, and we've made adjustments for that, he says, such as expanding tuning ranges. A few years ago, our transmitters would have had 256 channels across 25 MHz of bandwidth; now we're up to 6,000 channels to choose from over 144 MHz. The tuning-step sizes are packed much tighter, which provides more choices for frequency-coordination planning and lets users cover more area. That's especially necessary in dense metro areas with a lot of adjacent TV channels after the repack.
Steadily increasing channel counts, in sports and other verticals, remain a challenge, notes Jim Lappin, product manager, wireless microphones, Audio-Technica. Therefore, A-T, like other wireless systems manufacturers, has developed its own software solutions for frequency coordination. Wireless Manager allows users to create a device list, coordinate frequencies, and, when used with compatible Audio-Technica networked devices, can scan the RF environment, generate a coordinated-frequency plan, and push frequencies to receivers on the network. The software also allows remote configuration and control of A-T networked devices and can display key system parameters in real time.
It gives you a snapshot of the available spectrum between 470 and 608 [MHz], he says. Once you know where the TV channels are, you can plan around those frequencies.
Teaming Up Shure's Michael Johns: All aspects of content creation should be important to audio manufacturers, and sports is. Wireless microphones are how you get close to get that sound.
Last year, Shure and Q5X announced collaboration around new wireless transmitters that combine Q5X's hyper-compact form factors and safety-conscious industrial design with Shure's widely used Axient Digital RF technology. Axient's digital operation allows versions of Q5X's primary models - CoachMic, PlayerMic, AquaMic - to function as digital devices, conferring key features of signal encryption and improved spectral efficiency to Q5X's diminutive form factors. The new product - named Q5X QT-AD10 Axient digital wireless transmitter (the companies will sell it through their respective distribution channels) - also incorporates Q5X's Remote Control Audio System (RCAS), which provides remote-control functionality: on/off, frequency, mic offset, RF power, groups, and battery level.
In addition to adding digital-encryption capability to the product line, says Q5X
