UK Radio Frequency usage, licensing and policing (inears mics advice request)

JMP220478JMP220478 Frets: 355
edited July 21 in Live
Building up ch38 based / GB legal 606 -648mhz  based in ears / mic setup - to date used sparingly at rehearsal n at home - but aware licenses are required for legal use though finding  ofcom site / pmse and indeed various manufacturers usage pdfs at times  confusing . 
 Any advice appreciated 
1. Licenses / device. Or per user or per band ?
2. for kit sitting in licensed for event or venue (coordinated site specific ranges ) - how does that work ?
3. as a non pa hire user /owner  - am I really over concerned ? 
4. Has anyone ever found themselves being contacted over unlicensed legal frequency use or indeed unlicensed coordinated site specific kit ? 

Cheers for looking and any info shared 





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Comments

  • bob21bob21 Frets: 167
    I do this for a living.. though most of my coordinations run well into 3 figure quantities of mics and IEMs! 

    So the headline is, to use Ch 38 (606-614 MHz) you require a UK Shared license.. You buy these online, £75 a year or £140 for 2 years. 
    These license the licensee to operate all compliant PMSE (programme making and special events equipment (radio mics, IEMs) at 10mW EIRP (standard power on most kit); anywhere in the UK. 

    This spectrum is ‘shared’ ie you have no priority over other users, and no guarantees - but it is cheap, and you can stick 12ish mics in the channel, so you can usually make this work if there’s another band with stuff etc.. 

    In terms of licensed sites.. Ch38 is still available to you, and a licensee of a site or specific license can’t forbid you from transmitting inside Ch38.. What they may do however, is choose to assign you a frequency from within their licensed allocation (this is what we do at big festivals, to make sure everything plays nicely together!)

    Non-compliance with license conditions, or not having a license, is an offence against the Wireless and Telegraphy Act - which treats all operators of radio equipment the same, whether you are a PA company, a West End Theatre or Dave who plays bass down the Dog and Duck on Fridays.. 
    The penalties are to start with, confiscation of transmitting equipment, a hefty fine, and potentially a prosecution.. 

    Do I know anyone that’s ever been done for it? No. Would I take the risk on a multi thousand pound fine plus having my kit taken for the sake of £75 a year? Nah! 
    Plus sometimes it’s very useful to wave your license at somebody working without one, if you want them to go away!

    Hope that’s helpful.. but I literally talk about this stuff all day (I even deliver lectures on it sometimes) so really happy to answer more questions!!
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  • JMP220478JMP220478 Frets: 355
    edited July 22
    @bob21 ;;;

    Many thanks for this reply ...

    for clarification 

    1. if I get purchase a UK shared licence and provide kit in ch38 bandwidth to myself and band - as the licensee and my kit - do we need a license per musician? 

    2. the 10mw limit you mentioned  -  I can vary outputs on a sennheiser  g4 IEM transmitter - via menu - but purchased a G3 SKP plug in for use as a pedalboard transmitter / backup - which spec says RF output at 50 Ohm - typically 30mw ( is this illegal ? )  - btw just checked their latest G4 SKP 100 datasheet and it states same - there seems to be no RF power output option on these devices .


    3. is channel 70 kit worth investing in - both performance wise and its narrower frequency range and potential future ?

    4. what is back story of 700mhz range and its use in uk - been offered tonnes of kit recently - and been assured no issues with use in pub land ... 

    5. Looking at the BA2015 rechargeable battery packs for Sennheiser kit - is there a decent third party charger alternative to Sennheisers overpriced units 

    cheers 


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  • bob21bob21 Frets: 167
    @JMP220478 ;

    Sorry for the delay, been locked in a basement engineering outside broadcasts all week!

    1 - no, one license will cover you all - you are the 'operator' for all intents and purposes. They're pretty flexible with this - for instance if I was to hire you some mics, my license would cover you..


    2 - ah yes, both a) grey area, and b) complicated bit! The complicated bit is that the power limit on the license is based on EIRP, which is Effective Isotropic Radiated Power - or put simply, the actual power produced in the air out of your antenna. Obviously there can be losses or gains in this (depending on cable, antenna effeciency, etc) - so with your standard whip antenna on a Sennheiser beltpacks for instance, although there is 30mW of electronic power, the EIRP is a bit lower!

    Also the grey area thing - Ofcom are generally happy with allowing specific licensed frequencies to use up to 50mW EIRP if you ask them nicely, so there's basically a common knowledge that anything under 50mW would be extremely unlikely to be challenged!


    3 - Ch70 (863-865MHz - notably only a 2MHz chunk, rather than a full 8MHz as with other channels) is the 'license free' or unrestricted band. It's great, because you don't need a license, so it's cheap.. However you share it with literally anybody else who also didn't buy a license! So it's less reliable that you can find clear space in the channel, and you have no recourse to shout at other users! Obviously the fact it's only a 2MHz slot means you can get significantly less stuff in it - generally I advise that the max is 4 mic channels. In the perfect scenario, it is possible to squeeze 5 or 6, but rarely in the wild. And getting mics and IEMs to play together in Ch70 is likely to be a case of maybe 2 mics, 1 IEM if you're lucky..

    Currently there are no plans to remove the Ch70 spectrum, and it's been quite well protected so far.. So a reasonably safe bet for the future!


    4 - Well, back in the day, pretty much everything from 470MHz up to 900ishMHz was fair game and could be licensed. And then mobile telephony and digital TV happened, and spectrum started being sold off! So in 2012, we lost 790-863 to Digital TV, and then in May 2020, we lost 694-790MHz to mobile. So as of current, it is illegal to use any PMSE device in the band 694-790MHz.. and becoming increasingly inadvisable on the basis of other user's noise, regardless of the legality. The programme to clear 700 was accelerated by 18months, so some of the new users have taken a little while to come online fully, but we are certainly seeing significant noise up there now!

    So I certainly wouldn't suggest 'no issues' - and either way it's the wrong side of the law!
    A lot of the cheap kit is stuff that came over here cheap from the states when they did a similar clearance a few years ago, was used here for a bit, and is now effectively unusable, hence being sold on very cheap...!

    5 - Ah yes, BA2015, one of my least favourite products. They're not completely outrageously priced, compared to a Shure SB900 for instance.. But they are shite! I would probably buy Eneloop rechargeables, and then either just buy a desktop charger, or if you want something a little more road-ready, the Fischer Amps charger, which is a 1RU unit that chargers 16 batts!
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  • JMP220478JMP220478 Frets: 355
    @bob21 ;; - this is brilliant thank you ..  

    Have had some recommendations  re battery choice which is inline with yours - Ikea rechargeable batteries being possible  rebadged 
    Eneloops ? 

    I had a look at the Fischer rack unit - can see its benefits for someone like yourself - cant justify that at the dog n duck sadly - but any recommendations in the sub £100 bracket ?

    I'll probably steer clear of ch70 unless a cant resist deal comes along ,, 

    I will invest in a licence - legal requirement but as you say a piece of paper to tell others to go forth etc ... 

    Ive noticed some online users getting body packs modded with the solid  aerials - have you come across this and does it help increase signal reliability / range ?  and would this be a alternative to cranking up RF from transmitter in an IEM setup ?


    Bearing in mind the amount of now illegal kit available I'm surprised there isnt a some clever  bod ding mods to correct  the frequency range ?






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  • robinbowesrobinbowes Frets: 2398
    edited July 25
    I must confess, I don't really understand the RF world, mostly because I've never really been involved with it.

    However, that's changed recently as I've picked up a couple of SR2050 "AW" range, which is 516 – 558 MHz. Not sure what channel this is? This is the frequency sheet: https://assets.sennheiser.com/global-downloads/file/8583/2000_IEM_Series_Range_Aw_Frequency_Sheet_02_2017.pdf

    I got them for the singers in my band as I generally spend way too long sorting out their IEMs at our gigs (they have entry-level Shure gear which is poor). However, we're not gigging at the moment and they're currently on loan with a friend who runs a sound/light/stage hire business.

    I guess I'll need a licence to use them legally in the UK?

    I'd love to learn more about this. I don't suppose you've got any recorded lectures, have you @bob21 ?

    R.
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  • bob21bob21 Frets: 167
    @JMP220478 ;

    On battery chargers, sorry I have no ideas really.. I only tend to deal with the Shure SBRC stuff these days, and the Sennheiser 6000 stuff (which will make you think twice about how expensive a charger can be!!  =) )

    I can’t say I’ve ever seen modified beltpacks.. I think solid antennas on beltpacks would be more of a liability than a benefit - the flexible ones tend to get fairly trashed as it is by the handling/movement of performers!! 
    Also the limitation of a beltpack antenna is drastically outweighed by the other factors in play - the physical size, the severely limited ground plane, the limitations on shape, the proximity to large RF insulators & absorbers (or as otherwise known, the performers..!)..

    In general, the best performance upgrades to be gained in IEMs is good transmission practices, using quality combiners, good antennas placed well, and ensuring best placement of beltpacks relative to antenna and performer positioning.. 
    this is why I put my antennas upstage, sometimes even behind stage, so they have best chance of line of site to the packs being worn on the back of the performer! 

    I can also say with good certainty that you should be able to get pretty much anything that is smaller than an arena stage with a thrust done on 10mW of power! Generally cranking TX power actually makes existent problems worse, rather than fixing them!

    It is possible to move the operating band of some kit, but in a lot of cases this is a hardware change and prohibitively expensive.. also, licensed users, when cleared from spectrum, are usually offered a buy-back scheme by Ofcom that compensates for the need to buy new kit!
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  • bob21bob21 Frets: 167
    @robinbowes Its a world many don’t understand well, even within the live sound industry!! 

    So that frequency band comes under what is known as specific license, or site license.. so you have to buy a license per frequency, at a given location, for a given time period.. which makes them great for a theatre that doesn’t move, for instance, who would buy for the year (£28 a frequency) - or good for a festival where things are busy and I want to stick out of the way of other people, where I buy a frequency for 48hrs or multiples of (£8.50/frequency/48hrs).. 

    Unfortunately there’s no way to license them for any-place any-time usage in the same way the Ch38 license does.. perhaps not too bad if you only play a couple of venues, but a bit of a nightmare if you do £50 venues a year, and aren’t the kind of band that can’t justify sticking £20 on a couple of frequencies per gig.. 

    As a general note, licensing is all handled by Ofcom, specifically the PMSE department. You can ring them and talk to them, though they are sometimes less than helpful.. In reality they want you to do self service on the website! 

    I don’t have much publically online, though I was sent this link the other day to a virtual seminar I did last year. It was for the church market, so there’s probably a few references in there to vicars and churches, but if you substitute singers and venues, the concepts will still work the same! It’s called ‘10 Things You Should Probably Know About Radio Mics’ and is a 45ish minute romp through licensing, system deployment and some tips and tricks! It’s here: 
    https://youtu.be/uJPO3pZ7izA
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  • JMP220478JMP220478 Frets: 355
    edited July 26
    @bob21 ;; - many thanks for your excellent info / support  to date - watched the video and will probably revisit a number of times ...

    lots of things for me to review -  gain staging , pilot tone , antenna placement ( particularly this - as I've built a small test rack with a two IEM transmitters  and a mic receiver in  - I cunningly and clearly erroneously modified a Sennheiser antenna half rack plate to add another antenna ( shure x2 rx and senheiser x1 tx ) and wondered why performance was less than ideal -doh!  

    In a band mixed device type (  mics and iems )  scenario - using different mfg kit - what is simplest and budget friendly  way to avoid antenna farm issue ..  ideally dont want to  go back to multiple devices in gator bags lying around in rehearsal / onstage 

    Also -  belt pack format transmitter and receiver sets - like the Sennhesier camera units - are they an option for stage use as IEM ? 

    understanding only mono audio n no external volume control ... 

    final question for now - using ch38 ( licensed of course )  -  606.5 - 613.5  is it wise to space out the frequencies you select for use in this space - ie in a 4 device scenario  and with no other local users - adopt a min of 2 Mhz gap / device - 606.5 608.5 etc  ? 


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  • bob21bob21 Frets: 167
    @JMP220478 ;
    Sorry for delay, been up in Edinburgh putting in several hundred boxes of PA!

    Antenna farm.. best thing is to use an antenna splitter for mics, and a antenna combiner for IEM.. If it's just 2 ways, you can use a passive combiner/splitter, just need to make sure these are 75Ω and well isolated - such as a Shure UA221. Obviously all the manufacturers make their own splitters/combiners (Sennheiser ASA214 splitter, AC41 combiner, for instance) but there are a few cheapy splitters about, apparently.. I'm led to believe Thomann do a cheap one which isn't too bad.

    Camera kits - yes, can be done, but obviously significantly limited performance as it's tiny whip antenna to tiny whip antenna.. plus mono only, and the hassle of 3.5mm to XLRs all over the place. Not having a volume control on the ears pack is a bit of an ergonomic disaster too!

    Yes to spacing, but not to equidistant spacing.. Spacing aims to avoid products of Intermodulation Distortion - like a harmonic distortion series - so these obviously don't space perfectly - and interact somewhat with more and more mics.. In a simple scenario, it's usually best to go to the 'worst' (least agile, most bandwidth demanding) kit in the system, and see if they have a group/channel type structure published by the manufacturer.. So with some Sennheiser mics and IEMs, I would find the Group/Channel chart for the IEM, see which one fits in Ch38, then tune the mics and IEMs to frequencies within that group..

    The next step up from this (and where we go when mixing brands, different product lines etc) is to use some software to do the maths of calculating IMD products - the common tool for this is Shure's Wireless Workbench.. Senn also have Wireless Systems Manager, but it's not as good; though makes more sense if you're in a purely Sennheiser world!
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  • JMP220478JMP220478 Frets: 355
    @bob21 - many thanks again - I will inevitably have more questions as I stumble through this new area of live sound ( for me) . Cheers 
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