Wireless Audio, Part 1: RF Does More With Less, Because It Has To

In an era of constrained spectrum, two tactics have emerged: work closely with regulatory bodies and utilize engineering chops

The Federal Communications Commission, which oversees the invisible mesh of radio frequencies (RF) over which essentially all professional wireless communications travels, has relentlessly tightened the spigot on that resource over the past three decades. That happened most notably in the aughts, when the FCC auctioned off the 700 MHz spectrum previously used for analog broadcasting, and in the following decade, when the 600 MHz range went under the regulatory axe to feed a voracious digital-mobile industry. In the process, it has created two decades of particular angst for the professional wireless-microphone sector.

Atop that, the 21st century has seen an explosion of wireless platforms, from cellular phones to Wi-Fi everywhere. Broadcast-audio users - from the wireless microphones at the heart of the kit for day-to-day sports to the huge wireless intercoms needed for sprawling live productions like major-league drafts and event-level games - had to find ways to fit a seemingly infinite amount of data into an increasingly finite amount of spectrum space.

Their strategies revolve around two key tactics: one, work closely with the regulatory bodies like the FCC on policy matters to ensure a voice for professional wireless users in an increasingly DIY production landscape littered with iPhone-toting influencers; two, use their engineering chops to develop workarounds for constricted spectrum. The latter approach especially has produced some remarkable outcomes.

Most recently, that's WMAS (Wireless Multichannel Audio Systems), a wideband digital-audio-transmission technology that allows multiple audio channels to be densely packed within a single RF channel. This provides greater spectral efficiency and reliability than traditional narrowband systems, in which each channel uses a separate frequency. The technology and a corresponding FCC rule change were in development for more than a decade. Today, leading wireless-microphone systems makers have made it foundational.

How Mic Manufacturers Apply WMAS

Sennheiser's entry in the WMAS sweepstakes is its Spectera ecosystem, which uses WMAS as a base technology that puts microphones, IFBs, and control data - up to 64 channels (32 in/32 out) - together on a single wideband RF channel within a single TV-channel bandwidth (6 or 8 MHz). This contrasts with traditional systems, in which each element requires its own frequency as well as painstaking channel and guard-band planning.

Sennheiser's Joe Ciaudelli: Spectera allows a large sports production and an equally huge entertainment production on the same campus to use the same audio channel, without interference. According to Sennheiser Director, Spectrum and Innovation, Joe Ciaudelli, Spectera and WMAS are going to be critical to making RF manageable with events like this year's FIFA World Cup joining the usual array of high-channel-count broadcast-sports productions in the U.S. This month's 2026 Milano Cortina Olympics in Italy underscores the fact that spectrum constriction is a worldwide problem.

Spectera allows a large sports production inside a stadium and an equally huge entertainment production on the same campus to use the same audio channel, he says, and they can coexist without interference.

An offshoot of WMAS is dynamic resource allocation (DRA), a system that automatically adjusts spectral resources (frequencies, bandwidth, time slots) for microphones in real time, moving from static allocation to efficient, need-based distribution and using WMAS to optimize spectrum use, handle interference, and support more channels. Sennheiser has already integrated DRA into its Spectera system, says Ciaudelli.With DRA, resources are dynamically assigned according to immediate needs: for instance, giving more bandwidth to a sideline reporter moving around a stadium and less to a stationary source.

Shure has also integrated WMAS into its product line but to a less encompassing degree, instead emphasizing collaboration among wireless users in production environments.

WMAS is a wonderful technology that opens up all kinds of innovation for us as an industry, says Jason Waufle, manager, global strategic markets development, Shure. However, there is still a significant number of applications where a more traditional narrowband digital wireless system is more often than not the right choice, based on spectral efficiency and the resources we have available to us. Specifically, at a sporting event where you've got five or six or seven different stakeholders with a number of wireless products, you have to be using something that is spectrally efficient. All those parties can't have an entire TV station dedicated to them, so Shure's point of view is that we have to stay spectrally efficient and nimble in terms of how we deploy this technology that the FCC opened up for us.

UWB Adds a Dimension

Nexonic's Director Jackie Green: There's a lot of ways you can divide up that bandwidth. It's just that, when you're talking WMAS, you're still operating at the transmit powers that everybody already is operating at. Yet another technology that may help address spectrum shortage is Ultra-Wide Band (UWB), a short-range RF technology offering highly accurate, low-power wireless communication. Its main applications are in consumer and industrial categories; it's sort of a more muscular Bluetooth. Nexonic Director Jackie Green, an RF industry veteran and an advisor to the UWB Alliance, says it's similar to WMAS in that it utilizes more bandwidth to obtain better performance, operating with a 500-MHz bandwidth, in exchange for range. It can also operate over a wide set of frequencies, allowing for many options in trying

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