Radio Microphones licencing
In the UK there are particular frequencies and frequency ranges that can be used for radio microphones being used for Program Making And Special Events
I have trawled the Ofcom website to get an overview of the situation:
The PMSE Spectrum
The PMSE Spectrum is shared with terrestrial TV broadcasting and is shown below and on the Ofcom website http://licensing.ofcom.org.uk/radiocommunication-licences/pmse/pmse-spectrum
This means there are three areas of permisable transmision frequencies
The first is the Channel 70 which is between863 and 865 MHz which does not require a licence
Here is the Information from of com
Band: 863.0 – 865.0 MHz
Available frequencies: From 863.100 MHz to 864.900 MHz
No. of mics: Typically up to 4 frequencies can be used together.
For example, 863.1, 863.7, 864.1 and 864.9 MHz
Transmitter power: 10mW.
Second is Channel 38 which is between 606.500 and 613.500. and requires a user licence. This licence is valid for any of the licenses systems working in the channel 38 band in the UK
This band can be happily used for up to 10 systems working in one location without problems. See the 10 channel plan
Here is the Information from of com
RF bandwidth is limited to 200 kHz. Transmitter power is limited to 10mW if handheld, 50mW if body-worn.
UHF Licence is available – (1 year or 2 year Licence)
Channel 38 is available on shared non protected basis from 606.500 – 613.500 MHz. Licensees may use any frequencies within this range.
Guard bands have been included at each end of channel 38 to avoid interference with future services in channel 37 and channel 39 and facilitate free-roaming use throughout the UK.
10 Channel plan:
The UK Wireless Microphone Licence does not specify spot frequencies in channel 38 but the 10 channel plan below will ensure that all frequencies can operate in the same location without harmful interaction. This plan is a suggestion only. Users and manufacturers can devise their own plans that could involve any number of frequencies within the range.
|Channel 38 – 10 channel set ratings|
|2Tx IM(3) and 3Tx IM(3)|
In developing the plan Ofcom ensured that each frequency is safely spaced apart. However interaction can sometimes occur between frequencies even when appropriate spacing is applied. This unwanted interference can occur when equipment is operated close together in the same vicinity. It is known as intermodulation or “mixing”.
In the real world these unwanted signals appear on or close to the frequencies being used. To help make sense of this we have devised a figure of merit that we have called the “Risk Index”. This is calculated according to the quantity of unwanted signals and their spacing from the frequencies we are trying to use. Closer spacings have a higher risk of causing interference so are given a higher weighting in the sum.
thirdly there has recently been an addition to the PMSE shared user frequencies
There has recently been an addition to the PMSE shared user frequencies in addition to the channel 38 band there is a new band of frequencies between 823 and 832 MHz which are now under the same licence as the channel 38 “PMSE shared user licence” . So if you have a “PMSE shared user licence” you may well be able to licence the equipment that used to be used on the derg frequency , channel 70, so long as it can be tuned to this new band. here is the link to the relevant info on the JFM website service=all&freqStart=823&freqStop=832&unit=MHz&submit=View+results+below
And fourth, Coordinated frequencies which require a user site licence for each allocated frequency . So you cant get a coordinated licence then change frequency , site or operator without getting a new licence
Coordinated frequencies are licensed at a specific site for short or long term. They provide the best protection against interference from other licensees and are planned to avoid interference from television transmissions.
the Licence schedule will specify the exact frequency, the location and the dates of use.
It could, for example, be a short term assignment for a few hours use at an outside broadcast or similar short term event; an assignment for several days or weeks at a theatre for a touring show; or an annual assignment for on-going, regular use at a fixed site. Please note, annual assignments are only available to the owner / permanent occupier of the site.
470 – 790 MHz
These frequencies are shared with TV broadcasting on the understanding that there is no impact on households’ TV reception. In certain parts of the country a range of frequencies may be used without a problem, whilst in other parts of the country those same frequencies will be unavailable to protect households’ TV reception nearby. They may also be completely unusable due to interference from the same TV transmissions.
Some other channels in the PMSE Spectrum are sometimes licencible for radio microphones , but check with ofcom before committing to any equipment
A limited number of VHF frequencies can similarly be assigned on a coordinated basis.
Some channels in the 470 – 790 MHz range are currently being reviewed by Ofcom for other uses.