Wireless is no longer simply a means of removing cables from microphones, monitors and comms. As RF systems become more integrated, networked and centrally managed, they are taking on a much broader role within pro AV – providing an increasingly important platform for carrying audio, comms and data.
That shift has been decades in the making. Professional sound in AV and live performance saw the potential of cableless mics as far back as the 1940s, with systems coming into their own in the 1980s. Radio mics were the main application initially; in-ear monitors (IEMs) became more widely used in the 90s, when professional wireless intercom also emerged. All three use RF spectrum, though intercom has increasingly moved to DECT. Historically, they existed as separate components within AV infrastructure rather than as a connected whole.
This has created a situation where the consideration is no longer whether to use wireless technologies but how everything will work together and be managed. “The question is rarely whether to use wireless,” agrees Sound Devices marketing manager Ben Davenport. “It is how to make wireless dependable, scalable and easy to manage.” In practical terms, he adds, it means designing systems that can cope with different venues, changing RF conditions and higher channel counts without making things unnecessarily complicated for operators.
WIRELESS PREREQUISITE
René Moerch, group director of product management for wireless at Wisycom and DPA, agrees that wireless has become a prerequisite for large corporate and higher education installations, particularly at the top end of the market.
“The larger corporates and universities have taken some of the elements of broadcast into their daily work where, besides doing a lecture or presentation in the auditoriums, they’re also using audio and video for their communication both internally and externally,” he explains. “The systems have also become so stable, especially in fixed environments.”
Stuart Moots, director of market development for Shure, sees the same shift. “It still starts with microphones and IEMs but now touches networking software, monitoring, comms and, in many cases, IT teams,” he says. “The best modern wireless systems are not standalone, they are connected, monitored, coordinated and managed as part of the wider production environment.”
From the perspective of those working with end-users, the need to use wireless remains much the same. Pyers Easton, managing director of systems integrator and spectrum consultancy Raycom, which also represents Shure, Sennheiser, Wisycom and Lectrosonics, believes little has changed when it comes to planning RF distributed systems. He imparts that alternative technologies, such as private 5G networks, are still some way off and have drawbacks, including inherent latency.
For Emma Bigg, project manager at TAD (Technology Architecture Design) Associates, describes wireless as a “pretty accepted technology”. Wireless has simply become second nature, she says, a technology people trust without a second thought. System complexity still comes down to the application and client requirements, but Bigg believes most people are now making full use of what wireless offers, including networking interfaces for remote monitoring.
Duncan Bell, founder of Wideband Consulting, has watched wireless move from a technical headache to a creative enabler. He recalls that over 20 years ago it was something of a dark art, with real challenges around getting everything to work together. “Now it’s driving the creative input to shows,” he says. “We don’t have to stick within the boundaries of the stage anymore. There’s a consumer appetite for people being able to run around the auditorium or fly around the room and there’s a technological capability of delivering it on a routine basis.”
BUDGET DECISIONS
Budget, unsurprisingly, can dictate what wireless equipment is used. Marcus Blight, technical application engineer at Sennheiser, stops short of calling wireless a default for this reason, but acknowledges it has become close to an expectation.“Definitely from a creative standpoint,” he says. “It’s the demand created by the end-user visionaries, making the technical teams find the solution, which is becoming wireless.”
The appetite for wireless has grown slowly but steadily over two decades, to the point where wireless mics are now the expected standard, and Alex Lepges, technical director of Audio-Technica EMEA agrees. “A wired microphone, specifically for presenters, singers and artists seems to be the odd one out nowadays,” he says. “At the same time, the challenges on the availability of spectrum get more severe every year. But, as an industry, we are basically getting used to that and finding ways to cope with it.”
The availability of spectrum for programme making and special events (PMSE), which includes wireless mics, IEMs and communications, has been decreasing since the late 2000s. The last big upheaval was the sale of the 700MHz band to the mobile phone sector, which was agreed by the World Radio Conference (WRC) in 2015. Since then there has been debate over the future of the UHF 500MHz and 600MHz frequencies used by digital terrestrial television (DTT) channels, which are shared with PMSE.
At WRC-23 there was an undertaking that there will not be any review of UHF until WRC-31. However, the reality is that broadcasters are already beginning the transition from DTT to IPTV and streaming. The UK government’s Department for Culture, Media and Sport (DCMS) recently proposed several scenarios for DTT and PMSE, including releasing 600MHz in 2035 and 500MHz ten years later; bringing the clearance of 500MHz forward to 2035 (and at the same time switching fully to IPTV); or clearing 600MHz in 2035 with DTT continuing until 2044.
The reduction in available spectrum has led manufacturers and system designers to work round the problem by using frequencies not used previously, including 2.4GHz and DECT in 1.9GHz, as Alex Lepges at Audio-Technica outlines. As part of the last reallocation in the UK, PMSE users gained access to the DME (distance measuring equipment) band covering 960-1164MHz, also known as the Air Band because segments of it are used by commercial aviation.
SPECTRALLY EFFICIENT
Pyers Easton describes DME as the only useful band likely to continue, but notes it is a UK-only solution. Over the last 20-plus years manufacturers have been developing more spectrally efficient wireless systems, a trend which has coincided with an increasing shift to digital technology. The most recent of these is WMAS (Wireless Multi-Channel Audio System), developed by Sennheiser but also adopted by Shure for its Axient Digital PSM (ADPSM) digital wireless and in-ear monitoring platform.
Sennheiser’s first WMAS product is Spectera, a wideband, bi-directional digital wireless system. In addition to having up to 64 channels (32 in/32 out) in a single unit, Spectera also incorporates control functionality. Marcus Blight describes this as a significant benefit that contributes towards a wider ecosystem for wireless. “It is transporting data at the end of the day,” he explains. “For us that’s audio data but there’s nothing to say it couldn’t transport DMX or physical network data or some other communication protocol.”
Another approach to wireless as a production- or installation-wide infrastructure is Wisycom’s RF over Fibre (RFoF). This works by converting RF feeds into optical signals, usually at the antenna pick-up, and can operate over fibre cables many kilometres long. René Moerch explains that RFoF is used for large-scale fixed installations, in both the corporate and theatrical worlds. For huge deployments, he says, you can centralise your equipment, with receivers in a central equipment room. Meanwhile, fibre is already available in these corporate and other large format buildings because it’s part of the IT infrastructure. Moerch adds that DPA N-Series digital wireless receivers can also be remotely controlled and monitored through the Open Sound Control (OSC) protocol and integrate with network systems including AMX and Q-SYS.
Most Wi-Fi systems operate on 2.4GHz, which is now used for some wireless mics. Despite this, Wi-Fi is still not seen as suitable as a wireless audio transport platform, partly because it operates as either a unicast or broadcast system sending one connection, not multicast carrying multiple sources, as do radio mics and IEMs.
Richard Jonker, vice president of commercial business development at NETGEAR AV, points to Wireless N (Wi-Fi 4) and audio bridges from around 20 years ago as the last real attempt at this, with little progress made since. “We’re stalling because we have bigger fish to fry, connecting the entire global population over wireless devices like phones, tablets and laptops,” he says. “You can plug a Wi-Fi access point into an audio wired network and then do some wireless monitoring. It’s just that for full infrastructure mode over Wi-Fi, there’s no such thing.”
REMOTE SYSTEMS
Another application for 2.4GHz is running wireless data networks using the Zigbee/IEEE 802.15.4 specification. Sony introduced a remote wireless system based on this in 2008 that is still available as a remote antenna, according to pro audio lead Markus Warlich. “This can be powered over Ethernet and you can have several antennas in a system,” he explains. “You can run around your theatre and always have a connection to the transmitter to change parameters.” Sony also produces Windows-compatible software, Warlich notes, which can control every aspect of a receiver and a transmitter.
Such levels of control and monitoring are well established in broadcast and professional computing. While they were already part of wireless operations in AV and pro audio, these features are now expected and increasingly necessary. Software-defined systems and automation are rapidly becoming essential because the scale and complexity of wireless deployments have changed, according to Sound Devices marketing manager Ben Davenport. He says: “Modern productions often involve dozens or hundreds of wireless channels spread across large venues, multiple stages or entire facilities. Manual processes and fixed hardware workflows simply do not scale. AI or the cloud may have a role, but wireless still needs to function effectively in venues and on tour without high-speed internet connections.”
At Shure, Stuart Moots foresees wireless becoming more intelligent, connected and easier to manage at scale, with increased remote monitoring and deeper integration with IT systems. “AI can help by spotting issues earlier or simplifying coordination but it has to serve the engineer, not get in the way,” he says.
In the field, implementation can still be dictated by the job and who it is for. “It very much depends on the client, the application and the team involved,” says Emma Bigg. “We definitely see people using all the benefits of wireless systems with networking interfaces [for] remote monitoring. We also see people that don’t really utilise that. AI is certainly interesting and dynamic RF management is the sort of thing it would be good at.”
EMERGING METHODS
Duncan Bell acknowledges that new technologies and methods are emerging, but often in a pragmatic way that retains human oversight of spectrum planning. At Raycom, Pyers Easton is already using AI to help plan systems from site measurements. “I can load in rough notes and it will produce a report as a PDF with all the information,” he says.
While Marcus Blight at Sennheiser sees potential for AI and cloud management, he remains cautious. “There’s nothing to say PMSE bookings couldn’t be done by an AI agent mapping out events, spaces and the spectrum available,” he says. “But I don’t see a use for AI in real-time analysis just yet.”
Wireless audio has long since met expectations for quality; the bigger shift now is from individual devices to connected, managed systems. As deployments grow in scale and complexity, wireless is emerging as a more fundamental part of AV infrastructure – even if continuing spectrum pressures ensure that evolution will not be without its challenges.
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