Why Is UHF Spectrum so Important for Wireless Microphones?
For wireless microphone systems to work, we need access to clean RF (radio frequency spectrum) - this much is obvious. What is less well known or understood, is which bands – or sections – of spectrum are best suited to the operation of wireless microphone and in-ear monitor systems.
We can't, unfortunately, just use any spectrum – there are certain physical limitations that leave us with a clear choice of limited, but effective frequencies that work best for our application. The most popular bands used for wireless microphones over the last 50 years or so are referred to as UHF and VHF frequency bands; UHF (Ultra High Frequency) in particular is the preferred space in the UK.
Although we cannot directly compare radio frequencies to sound waves, one characteristic they do share some similarity with is wavelength. Much like sound waves, lower frequencies have a longer wavelength, and, therefore, their propagation characteristics are stronger, which means they penetrate surfaces better and traverse greater distances without the need for a boost.
In a nutshell, UHF bands offer the largest quantity of good quality spectrum at the best frequencies required for large professional events.
Additionally, we can easily account for TV interference in the UHF bands as it is predictable - we cannot say the same for other parts of RF spectrum as these are often de-regulated and shared by technology such as WiFi.
Important changes to UHF Spectrum that affect you.
For years, professional wireless microphones and in-ear monitor systems happily shared UHF spectrum from 470 - 865MHz as a secondary user alongside the transmission of analogue television. Recent years, however, have bought about remarkable changes that significantly reduce our access to the all-important UHF space.
The short story is, back in 2003, the UK government announced it would be switching traditional analogue television services to digital. The immediate assumption was that this process would free up large portions of spectrum, and subsequently, it could be sold for a profit to the highest bidder. This process, and the income it generated for the UK Treasury became known as the Digital Dividend Review (DDR). Inevitably, with the rise in demand for mobile broadband, the majority of auctioned spectrum was re-allocated for use by the mobile industry to deliver next gen 4G services.
The first significant portion to go was the 800MHz band, but it won't be much longer before 700MHz suffers the same fate. To really bring the point home, it takes us from this:
UHF spectrum before DDR - (Green represents spectrum available to wireless microphone users. Yellow is dedicated space for PMSE. Blue is unlicensed, deregulated spectrum)
(Post DDR UHF with red representing the loss of 800MHz and 700MHz)
As the above charts demonstrate, the space available to us has reduced significantly, and while there is space left for now, a pattern is clearly emerging.
Mobile is important too!
From what we've described so far, it could be easy to assume we're anti mobile phones - we're really not. We understand the need for internet access on demand; the benefits this brings consumers, and the contribution instant access to information has made to our lives. However, pursuing with a strategy of expansion at all costs, simply isn't viable.
You can't get away from the fact that spectrum is essentially a natural resource – just like oil or gas – and if we continue to consume it at the rate we are, we will eventually run out. The harsh truth for our industry in-particular is that while the demand for wireless microphones continues to rise, the amount of space available to reliably operate them in is actually decreasing.
Ironically, the prospect of a severely impoverished wireless microphone operating space actually affects the mobile industry too:
Think about it, what do people use their mobile phones for (other than to make calls)? They consume content, right? The very same content that relies on wireless microphone systems to meet production value expectations. It might not be obvious to the average consumer, but wireless systems are everywhere when it comes to producing TV, video, live music shows, theatre productions, and even YouTube videos from the increasing number of 'YouTube stars'. To remove wireless microphones from the equation would mean setting production values back by half a century. This would make streaming HD content on your phone somewhat less appealing, don't you think?
The point is, changes to wireless spectrum affect everyone. Therefore, it is not the sole responsibility of any one industry or institution to take the entire burden. Demand for spectrum certainly isn't going anywhere; what's certain is that we need to achieve more with less (and that goes for everyone). It is in the interest of new users to recognise, respect, and co-exist with wireless microphone users to ensure we satisfy modern requirements.
What we're doing to help: spectrum efficiency
One way we're doing our bit to ensure a more sustainable future is through spectral efficiency - a journey that started with our flagship wireless systems, Axient.
Axient pioneered a range of new to the world technologies – partly centred on the needs of engineers, but also offering truly exceptional RF performance through features such as automatic interference detection and avoidance. While limited to our flagship Axient system at first, our intent was always to replicate these features – wherever possible – throughout the entire Shure wireless portfolio. Subsequently, many of the advanced wireless technology features originally exclusive to Axient are now found across our wireless portfolio – right down to our consumer level options. Given the uncertainty of a congested RF landscape, having a spectrally efficient wireless system is essential – no matter what your budget.
What you can do to help
The fight to save the future of wireless microphones for future generations doesn't end with manufacturers; you can do your bit too. Here are three ways you can get involved:
1. Spread the word
Education is key to ensuring a sustainable future for all wireless spectrum users. To help raise awareness of wireless technology and the ongoing changes, we set up LosingYourVoice.co.uk
The initiative contains a crucial overview of the current RF landscape and links to useful resources. By sharing this website, you can help us ensure a more stable future for wireless audio.
2. Become a Wireless Expert
Parallel to Losing Your Voice, is our Academy training platform. One of the key contributions users can make to the wider industry is to learn how to run their wireless rig as efficiently as possible. Check out our Wireless Mastered seminar and Spectrum Management Masterclass (How to master Shure's Wireless Workbench 6 coordination software) to help you run your next show with complete peace of mind.
3. Support with BEIRG
Engineers and audio industry professional wishing to get in the trenches so to speak can get involved with The British Entertainment Industry Radio Group BEIRG.
BEIRG is an independent and non-profit making association, working for the benefit of all those who use radio spectrum.
Have your say
Have something to add to this article? How are the changes to RF spectrum affecting you?