News - 20/01/2012

Don't lose your clarity

Do you know if the digital switchover will affect your radio microphones?

Radio Microphone Systems – The reason for change, digital switchover 2012.
Are you aware that the Government is selling off the radio microphone Channel 69 frequency band as part of the Governments' 2012 digital switchover policy? This means that the majority of existing radio microphone systems, will cease to work.

Towards the end of 2012 (just after the Olympics finish), these channels will cease to be available for radio microphone users. They will be sold to the highest bidder, expected to be a mobile phone provider for the new 4G band. Ofcom is also clearing bands 61 to 68 as part of the sell-off. Channel 70 (863 to 865 MHz, de-regulated) is reported to be un-affected, although there will no doubt be major problems in 2012 when many thousands of users that do not want to buy new systems and have product that can be re-tuned to Channel 70, will start using it.

Channel 70 will become totally oversubscribed and also there is a distinct possibility that the high power 4G transmissions could affect Channel 70, although until transmissions start, this cannot be confirmed. All radio microphone systems that can currently tune to channel 70, do not have the bandwidth to tune to the new allocated radio microphone frequencies (Channel 38 and above).

VHF radio microphone systems are not affected by the change in frequencies but VHF radio's are now effectively obsolete, none of the major radio suppliers manufacture VHF systems anymore, and have not done so for over 5 years.

The Government has allocated Channel 38 to replace Channel 69, but unlike Channel 69, it cannot, at this time, be used across the whole of the UK, mainly due to it being used in part of the country for radio astronomy.

Availability
The radio microphone manufacturers have all advised that once the switchover takes place and large numbers of users suddenly find they need to purchase new systems, there will be a considerable shortage of radio systems becoming available, unless of course the radio suppliers make very accurate guesses as to how many systems they need to be manufacturing between now, the switchover, and immediately beyond.

Additional Information
Since the middle of 2010, Sennheiser, Shure, Trantec and other leading manufacturers have introduced new Channel 38 (and above) frequency bands for their existing higher quality systems. They are still making products that tune to Chanel 70 (of which many systems can also tune down to 69 or lower, but whereas they will work now below Channel 70, they won't for much longer. Unfortunately, many of the smaller dealers are still not aware of exactly what the situation is.

Confused?
If you are confused by the digital switchover and how it affects your existing radio microphones, please contact us and our dedicated team of sound specialists will be able to clarity any worries and questions you may have.

FAQs

What is a radio microphone system?

A radio or wireless system takes a signal and puts it in another place. Whatever signal, whether it's a guitar, voice or anything else will be transmitted from a transmitter to a receiver, without a physical connection between the microphone and the receiving equipment

Why are they needed?

Cabled microphones can be used, but most users prefer the freedom to move around without the restriction of cables, when you use a radio system, cables are not required. The radio frequencies travel invisibly through the air.

How far will they transmit?

There are many factors that dictate just how far a radio system can transmit. Signals transmit through most materials, including brick, wood, plastic, even our bodies. Metal restricts radio transmissions and the more materials the signal needs to travel through, the less will be its range. Another factor is whether or not there are other radio systems being used at the same time in the immediate vicinity.

What types of systems are available?

Individual systems can be handheld, lapel (also called lavalier), headband or instrument systems. All systems can be used together, providing every system is set to a different frequency.

Is a license required?

Radio systems are available in two frequency bands in the UK, VHF and UHF. In both bands there are some license exempt frequencies, in VHF they are 173.8MHz to 175MHz, in UHF it is from 863MHz to 865MHz. All other frequencies require a licence to be purchased.

Generally speaking most amateur users who only require 1 or 2 systems, tend to opt for the license free bands but professional users, such as education establishments, corporate clients, theatres etc. should virtually always use licensed systems. The licence is supplied by JFMG (www.jfmg.co.uk), further information can be found on their website.

Can several radio systems be used together?

Yes they can but the preferred method from all manufacturers is to link the systems using an Antenna Distribution System (ADU), which uses one set of aerials and shares the signal between radio receivers. Any multiple radio system has just two aerials which are connected to the distribution unit(s). This reduces the probability of interference between adjacent radio systems, increases the system gain and improves overall performance. Up to four radio systems can be used with one ADU. Multi channel systems should also use high gain remote antenna's, not the low cost antennas supplied with the radio systems.

What is the difference between single channel and diversity?

Single channel receivers have one antenna and one receiver circuit, these are rarely used nowadays, only on very low cost systems. Diversity receivers have two antennae and a circuit which selects the strongest signal.

How many transmitters can be used with a single receiver?

Just one. Two transmitters operating on the same frequency will interfere with each other. It is possible to have both a handheld and guitar transmitter on the same frequency, and use them with the same receiver, but not simultaneously. These are called "duplicate" transmitters.

Can systems be mixed from different manufacturers?

Theoretically yes, but careful attention must be paid to specifications, because different systems have different technical parameters for equalisation and compression. It is not advisable to mix them.