New WMAS Standard Promises More-Flexible, Protected Wireless Operations Shure, Sennheiser establish early beachheads in what could be a game-changer By Dan Daley, Audio Editor Wednesday, November 6, 2024 - 7:00 am
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The lengthy narrative around the arrival of Wireless Multichannel Audio Systems is seemingly at its end. In October, the Federal Communications Commission (FCC) conferred its bureaucratic blessing on the RF technology that allows significantly denser multiplexing of audio channels onto a single wideband RF carrier. Referred to by the only slightly less unwieldy acronym WMAS, the new standard promises an easier and more flexible wireless workflow and greater protection for other services sharing the same frequency band. It is widely considered a game-changer for managing wireless signals in a narrower, denser spectral environment in the wake of multiple spectrum reductions over the past two decades.
The approval has also opened a new front in the wireless-microphone competition, one in which two of the sector's largest brands, Sennheiser and Shure, have quickly staked substantial claims.
Sennheiser's Joe Ciaudelli: With WMAS, you're using the same RF channel and the same amount of bandwidth for [multiple mics] as for one.
It is definitely the start of a new era of wireless-microphone technology, says Joe Ciaudelli, director, spectrum and innovation, Sennheiser. Noting the nearly six years the FCC spent considering the technology and the eight months, from February to October, it took to publish its finding in the Federal Register, he adds, We expect the competition to be rigorous.
Shure Senior Director, Product Management, Nick Wood puts the arrival of WMAS into broad context: Any change in the UHF TV bands is a really big deal given the changes that have happened over the past 20 years, most of which affected access to spectrum. This one is a great development because it changes what we can do with it, and Shure has been determined to push the envelope with spectrum efficiency. What can be done with the spectrum that we have and the WMAS regulations unlock a new innovation space for us. We want to use that to let the people who produce these events, including broadcast sports, to be able to do more with the spectrum they have that day and be able to say yes to one more wireless microphone.
Two Competitive Fronts Sennheiser's flagship WMAS offering is the Spectera line, introduced at IBC in September (the technology is already an ETSI standard in Europe) and demonstrated at the Americas Spectrum Management Conference in Washington, DC, last month. It features wideband, bidirectional bodypacks and a central unit that can handle up to 32 I/O. Its bidirectional wireless ecosystem supports data and audio control in a single RF carrier for all components and for such parameters as IEM volume, audio level and settings, RF health, and battery status. Sennheiser asserts that it is able to accommodate an entire production in a single wideband (6- or 8-MHz) RF carrier.
Shure's entry takes the form of a new iteration of the company's Axient wireless series: Axient Digital PSM combines its first digital wireless in-ear monitoring solution with its first WMAS-enabled product. It was announced Oct. 22 (although it had been selectively previewed privately two weeks earlier during the AES/NAB expo in New York, at which Sennheiser did not exhibit). Stereo capability enables Axient Digital PSM to operate as two discrete channels, allowing a stereo audio channel to function effectively as two mono IFB channels. Additionally, the capability to send Dante signals to the Audio Digital Transmission Exchange (ADTX) simplifies routing. The WMAS wideband implementation supports up to 28 channels per 6 MHz in the U.S. and 40 channels per 8 MHz in Europe; a narrowband mode provides access to more RF output power per channel while maintaining spectral efficiency at 17 channels per 6 MHz.
Changing the Game The new FCC rules will allow WMAS to operate in the broadcast-TV bands and in the 600 MHz duplex gap on both a licensed and an unlicensed basis and in other Part 74 LPAS (low-power auxiliary stations) frequency bands on a licensed basis. Power restrictions are 50 mW in the VHF-TV bands, 250 mW conducted power in the UHF band, 20 mW in the 600 MHz duplex gap (653-657 MHz), 250 mW conducted power in the 1435-1525 MHz band, and 1 W conducted power in all other bands, according to the FCC's website. WMAS will enable more wireless microphones to operate in the available spectrum (more microphones per megahertz of spectrum), providing additional options when more microphones are needed.
The WMAS rules do not alter existing spectrum rights or expectations regarding spectrum access and availability related to other authorized users' sharing the frequency bands with wireless-microphone operations (including, for example, broadcast licensees, Wi-Fi, and white-space-device users).
Sennheiser's Take For broadcast-sports applications, Ciaudelli - who contends that Spectera is the most innovative product the nearly 80-year-old company has ever produced - notes a broadcaster's typical complement of one transmitter for a microphone and one receiver for an IFB. That, he says, can be condensed into a single transceiver using Spectra WMAS. There's a similar benefit for large-scale events, such as the Olympics, in which various echelons of wireless mics are in either active or on standby status as a production unfolds.
With WMAS, he explains, you could give the vast majority of the spectral resources to the mics that are currently on-air. The mics that are, let's say, on deck' you give just enough resources to make sure that they remain linked to the base station in a ready mode. You're using the
