The topic of licencing is a source of much confusion among professional audio engineers. Specifically, it is not always clear when a licence is required to operate, or how to obtain one for the legal operation of wireless microphone or in-ear systems.
Before we get started, it’s important to note that licencing rules and structures do vary from country-to-country. The information we’re about to relay refers to the UK licencing structure only.
Licence Free Options:
The 2.4GHz band is a de-regulated block of spectrum available worldwide for a variety of services, including wireless microphones.
2.4GHz systems are ideal for small systems of around eight channels. One of the significant advantages to 2.4GHz is that you can operate licence free on a global basis.
Regarding channel count, 2.4GHz is well known as the home of Wi-Fi. For this reason, total system count is limited to approximately eight channels before you will run into interference problems.
The other important point to consider with 2.4GHz concerns operating range. The frequency is high, which makes the wavelength shorter, and this ultimately limits the operating range when compared to lower-frequency-band systems.
863 – 865MHz
Otherwise known as deregulated European spectrum, the 863 – 865 band is a small 2MHz slice of spectrum available for licence free wireless operation. The maximum capacity (depending on your system) is around 3 – 4 channels of wireless microphones or IEM’s. Again, because you’re sharing this space with other wireless devices (not just wireless mics and in-ears), you will need to be wary of potential interference.
606 – 614MHz (or Channel 38)
Channel 38 is available across the UK for a nominal licence fee and is solely dedicated to wireless microphones and in-ear monitor systems. Unlike the licence-free bands, you don’t have to share space with other wireless devices — you only have to account for other wireless mic and in-ear users. While this makes coordination a little easier, it’s still best to perform a full scan when you arrive on site to avoid stepping on other peoples toes.
Concerning channel count: channel 38 is only 8MHz wide, which means we’re still only looking at around 10 – 12 systems. For larger channel requirements, you’ll need to consider using our final block of spectrum — the interleaved bands.
A note regarding 1.8GHz:
1.8GHz is available for radio mics and IEM’s as part of the shared CH38 license. While not many manufacturers currently offer equipment in this band it does offer a viable alternative to the UHF bands. Digital equipment in particular would be able to take advantage of this band as they are in many cases more spectrally efficient than current analogue counterparts. The only thing to bear in mind with this block of spectrum is that antenna placement selection and placement is likely more critical as the operating range of systems in 1.8GHz will be less than UHF due to shorter wavelengths.
470 – 790MHz (Interleaved Spectrum)
Excluding channel 38 above, 470 – 790MHz is referred to as interleaved spectrum. The term “interleaved” refers to how we share this space with existing digital TV channels. Essentially, we can operate in the gaps between each TV channel; these gaps are sometimes referred to as “white space.”
The licencing for interleaved bands is managed on a per-frequency, per day basis. Say for example we needed to run 60 channels of wireless for a particular event. In this instance, we would licence 60 individual frequencies for a duration of 24-hours.
The Bottom Line
For any production requiring more than eight systems, you will require a licence to operate legally in the UK. All UK licencing is managed by the communications regulator, Ofcom. You can obtain a licence by visiting their website: http://www.ofcom.org.uk/