Backstage: Are wireless mics under threat?
The wireless microphone has played a major part in making theatre shows bigger and more extravagant. These operate on frequencies in the radio spectrum, a limited resource that, in the past 10 years, has been increasingly sought-after by mobile phone companies. A series of reallocations has resulted in less spectrum for theatre, live event and TV production, causing concern that the large-scale shows audiences now expect could be more difficult to stage in the future.
Major changes in spectrum allocation took place in 2012; the incremental switchover to digital terrestrial television (DTT) throughout the UK was completed and at the end of the year users of wireless mics and in-ear monitoring systems – who come under the umbrella description of programme makers and special events (PMSE) – had to give up the frequencies they had been using in the 800MHz band.
The freed-up spectrum was auctioned off to mobile phone operators keen to offer not just extra capacity for their growing number of users, but also faster video streaming and general wireless broadband connectivity. After much lobbying, the PMSE community was allocated new frequencies, including channel 38 and spectrum in the 700MHz band. The reallocation caused considerable disruption: hire companies, theatres and broadcasters had to buy new wireless mic equipment – with some government assistance through a compensation scheme – as well as dealing with fewer available frequencies in some parts of the country.
Just as the situation seemed to be settling down, the World Radio Conference announced proposals to clear 700MHz in favour of more mobile broadband and emerging technologies such as LTE (long-term evolution). Ofcom has now accelerated the process of clearing 700MHz, with the project to be completed by the second quarter of 2020, 18 months earlier than originally proposed. This has ramifications for DTT – there is the possibility of interference from new technology devices and Ofcom estimates 50,000 Freeview aerials will have to be replaced or retuned – but the future is more uncertain for PMSE.
Under Ofcom plans, PMSE operations will move to 960-1164MHz, commonly known as the air band. This is currently solely used for distance measuring equipment transponders on commercial aircraft in UK airspace. Ofcom says it has agreed terms with the Civil Aviation Authority and is confident the air band is suitable for PMSE and, after carrying out assurance tests, can be shared safely.
Despite Ofcom’s plans and timetable, many theatre sound designers and hire companies feel uncertain about the future. “We’re in a state of flux,” says Duncan Bell, a director of rental and audio design company Autograph Sound Recording. “There is pressure from mobile operators to get more spectrum. Ofcom is responsible for managing spectrum but we [in PMSE] need to find a solution to address our nomadic problems.”
This aim doesn’t appear to be helped by a lack of answers to key questions. “The timetable is running but there is no certainty that the alternatives offered by Ofcom are viable,” Bell says. “At the moment there is no wireless mic equipment that can operate in the air band. It’s also difficult to say what impact there will be on existing equipment. It’s hard to define how much spectrum will be available from location to location and how much of the air band we will need to do what we do.”
What you need to know about digital wireless microphones
What is the radio frequency spectrum?
It is the part of the electromagnetic spectrum, ranging from 3Hz to 3000GHz. Electromagnetic waves, known as radio waves, are an essential part of modern technologies, notably telecommunications and broadcasting.
What is white space?
These are the interleaved gaps between TV channel frequencies. White space is widely used by PMSE operators in theatre and live events for running wireless mics and in-ear monitors. New consumer and industrial wireless technologies known as White Space Devices are being developed to operate in these areas, with the ability to detect frequencies that are not being used. White space is seen as a key part of the ‘internet of things’, which will be used to control devices fitted with suitable sensors, such as heating thermostats and refrigerators.
What are the pros and cons of digital wireless microphones?
The benefits are seen as better sound quality, longer battery life and the ability to offer more channels in a smaller amount of spectrum. The downsides are the cost and the latency (delay) that digital processing can introduce on a signal.
Tuomo George-Tolonen, manager of the Pro Audio Group at Shure Distribution, which handles the Shure brand of wireless mics in the UK, observes that not all the air band would be available because the requirements of the existing user need to be protected.
By 2020, he warns, the clearance of the 700MHz band will leave PMSE users with 200MHz less spectrum than in 2012: “This reduction doesn’t make wireless operation impossible but it certainly makes the process tough, particularly at large events.”
Alan March, senior manager for spectrum affairs at wireless mic manufacturer Sennheiser and a spokesman with industry body British Entertainment Radio Industry Group, comments: “It will be quite difficult for top-end productions to cope and some of the bigger productions could be severely compromised. There seems to be no urgency in this. The government has agreed some form of compensation but we don’t have white space maps to see where things will fit in.”
On the subject of compensation, an Ofcom spokesperson said: “Government has agreed to fund a grant scheme to support equipment owners and has asked us to set up and oversee this scheme, which we will announce soon. Our aim is to allow the [PMSE] community to thrive, while ensuring the UK’s mobile infrastructure can support consumer demand and economic growth.”
Manufacturers including Shure and Sennheiser see digital systems as the best way of maximising available spectrum. Shure has produced prototype equipment aimed at the air band that has being tested at various locations in the UK, while Sennheiser recently released a second digital wireless system, the Digital 6000 series.
Terry Tew, founder of Terry Tew Sound and Light Hire, which rents radio mic systems to major broadcast productions, says people will have to go digital but that it is early days for the technology. “We’re still testing digital systems to see if they’re as good as analogue,” he comments. “Ofcom is saying we have to change the way we make TV but we can’t put dancers on Strictly Come Dancing on cable mics.”
Bell sees this kind of big TV production as potentially being more affected by the changes than theatrical shows, although there are still potential difficulties for theatre. “There are already problems for provincial theatres in some areas,” he says. “After the 800MHz clearance, Bristol and Woking, for example, were very squeezed for spectrum. The scale of West End shows won’t be affected because, generally, there is enough spectrum in the area and the people working on such static shows are good at planning.”
Even so, Bell concludes that this latest reallocation of spectrum will have a bigger impact on wireless mic users than last time. And there’s now less time to prepare for a still uncertain future.
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