What’s happening to 700MHz and how can you prepare?

Shure Pro Audio Group manager Tuomo Tolonen tells Audio Media International how users of wireless equipment can prepare ahead of the 700MHz clearance currently being rolled out across the United Kingdom.

Across the industry, many audio professionals will clearly recall the Digital Dividend Review and the subsequent loss of 800MHz band UHF spectrum for use by wireless microphones. As part of the clearance process, the designated, protected home of wireless microphones moved from Channel 69 to Channel 38; this key change (among other developments) is now pretty common knowledge among users of professional wireless kit.

Following 800MHz, however, the interest and willingness to follow the continuous developments concerning spectrum reallocation dwindled. As a result, the more recently announced plans to clear the 700MHz band and its consequences to the PMSE sector are far less known.

The 800MHz band clearance was inextricably linked to the process of switching from analogue to digital TV. Consequently, the entire process was very public and it affected the whole nation; 700MHz doesn’t affect the greater public in the same way. It’s an evolution of the original event – it’s less visible in the media – and therefore, users of radio mics are less aware of the impact caused by losing another critical band of spectrum.

Before considering how best to prepare for 700MHz, it’s important to get our facts straight. Here’s what you need to know:

694 – 790MHz will be cleared in the UK by May 2020. In fact, the process of clearing Digital TV (DTV) from this band has already begun across the UK, and similarly to 800MHz, it will take place region-by-region. Many homes will need to retune their TV – some will require new aerials. Ultimately, PMSE (Programme Making and Special Events) will no longer have access by May 2020.

The clearance doesn’t just affect users in 700MHz, it also affects users in the spectrum below 694MHz, as DTV transmitters will need to be re-purposed in the spectrum below 694MHz. Ultimately, the result is a more congested RF landscape (once again) for PMSE users.

So what can you do to prepare? Fundamentally, there are three core points we should cover:

1. Be aware of what’s happening. Understanding what spectrum is available to you in a given area and how Ofcom is managing the spectrum is critical to achieving successful productions. Anyone who owns gear in the 700MHz band as well as below 694MHz will be affected by this clearance. To see how the clearance might affect spectrum in your area, refer to Ofcom’s 700 MHz planner. (Details are subject to change, but it’s a pretty good indicator).

Those who take the time to understand spectrum policy and regulation will be best placed as engineers to work within the RF environment post clearance. Additionally, the government is in discussions with the industry to agree on compensation packages for affected users. Therefore, it stands without saying that it’s in your interest to understand potential compensation options.

2. Users need to become more mindful and understanding of how they deploy wireless systems. Wireless microphones are critical to modern production values, but it’s those with a genuine understanding of how to efficiently deploy and coordinate world-class wireless setups that will truly lead the next generation of events. Ultimately, a larger pool of qualified well-versed engineers will help to mitigate some of the potential issues that a more crowded, post 700MHz world will throw at us. To help equip engineers with the knowledge they require, Shure regularly run best-practice training and workshop programmes through the Shure Audio Institute.

3. Embrace new wireless tech. One side benefit of a continuously decreasing RF landscape is that it does encourage manufacturers to innovate. Next-generation digital wireless systems (such as Shure QLX-D, ULX-D, and Axient Digital) are all great examples of how wireless tech has stepped up to the challenge. And while digital wireless alone is not a magic bullet answer to spectrum congestion, it’s absolutely true that a well-engineered, linear and robust digital wireless system is more spectrally efficient than its analogue counterpart. For example, with Axient Digital, we can place more than three times the number of frequencies per MHz than with its analogue counterpart. In HD (High Density) mode, we can take this spectral efficiency even further by up to three times this amount once again.

In the grand scheme of things, digital wireless mics are a fairly new development, and while there is a small learning curve, it’s critical that we as engineers stay on top of the tools available. Ultimately, a solid understanding of new wireless tech, fundamental RF principles, and upcoming changes to spectrum are the best ways for any engineer to prep for a future post 700MHz.

Tuomo Tolonen is responsible for the management and continued development of the Pro Audio Division at Shure Distribution UK.