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Radio mics---we might have a problem


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Hey peeps,


Iam hoping someone might know the real truth behind what could be a real myth appering.


I was told yesterday that digital television have bought up all the frequencies currently populated by most radio mics, this technicaly means that when broadcasting goes live all recievers will just play out white noise.


True or false? does anybody know????



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As far as I am aware, the government is currently looking at the reallocation of certain parts of the radio spectrum, due to the impending analogue TV switch-off and the rapid expansion of bandwidth for digital systems.


From what I have read on the subject, however, I do not believe that we have too much to worry about in the short term. Any relocation will probably not take place within the useable lifespan of many current radio mic systems (the phased switchover begins in 2008). If it does move, the biggest problem is most likely to be the legality of your old systems, not whether they will keep working or not (as in the current situation with some older VHF units). If there were audio related problems I doubt very much they would just be the emission of noise, although this is totally dependant on what moves into the original unit's frequency band.

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have a look at Ofcom's news release regarding "the Ofcom Digital Dividend Review (DDR). By which they mean the reallocation of available frequencies to bandwidth - hungry digital TV. The white noise bit of the story I'm not really qualified to comment on, but I suspect urban myth in the making.


for some reason the link can't find the page, so go to the ofcom homepage, navigate to media and analysts > news release archive > news releases 2005 > News releases November > item dated 17/11/05 ref the DDR.


:unsure: Link fixed B-)

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... goes live all recievers will just play out white noise.

Not necessarily.


It will all come down to relative signal strength that the reciever gets. If the mic signal is strong and the TV signal weaker then the receiver will latch onto the mic no problem. If the mic signal is weak, then the receiver wont latch to the mic in the presence of a significant alternative signal. If your radio mics use tone squelch then the receiver will know its not latched to a mic and mute the output. If theres no tone squelch, then you probably will get hash.


If your radio mic system uses receivers with active antennas at FOH a long way from stage you'll be looking for difficulties. if your receivers work fine on short antennas and are colse to the mics it'll probably work Ok.


But will it be legal.....???

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Reading between the lines on the JFMG site, the problem is less technical than it is financial and bureaucratic. The medium term plan is to shut down all analogue TV transmissions in a few years and this will actually free up huge swathes of spectrum. Some of this will go to more digital TV, but there's also a queue of other users looking for frequencies.


As with the auction for G3 mobile services, the men in grey suits at the government are having their eyes light up and hearing "kerching" noises at the thought of selling off frequencies to the highest bidder. Radio mic users are unlikely to be the highest bidders....but JFMG is in there lobbying on our behalf!



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There is already a proposal to give the licenced VHF band (211.9 to 217.1MHz) over to Terrestrial Digital Audio Broadcasting. I believe quite a few broadcasters use this for talkback and radio mics.


The Ofcom proposals state that for the 470 - 862MHz UHF spectrum, 32 blocks of 8MHz will be retained for use by digital TV, and the remaining 14 will be available for "new uses".


According to JFMG, 50% of licenced radiomic use is in the spectrum released for new use. Furthermore, there are increased problems with interference when trying to interleave TV broadcast and radiomic usage.


I understand that the degree to which radio mic systems will be affected will depend upon their switching range, proximity to TV transmitters etc.


The Ofcom letter states, "The main purpose of this letter is to give you notice that your use of equipment in the 470-862 MHz band may well be subject to change, and any licences you have relating to this band may be revoked or varied by Ofcom so the spectrum can be redeployed for new uses. Most immediately, you should take careful account of this risk before making any decisions to invest in equipment for PMSE use in this band.(my emphasis) Only in very exceptional cases, where licensees have not had sufficient warning of the details of the changes (including this letter), so that they could deal adequately with any consequences, might Ofcom consider whether, subsequently, some form of assistance may be

appropriate. Ofcom would not for example consider any request for compensation in relation to equipment purchased or hired in this band from the date of this letter, except in very exceptional circumstances.

We will, of course, seek to give you as much further and advance notice as possible of the details of any decision to revoke or vary your PMSE licence(s)".


The JFMG Plasa presentation states that there are some benefits:


- Secure programmemaking spectrum from predators

- Acquire new spectrum (trading and auctions)

- Programmemakers benefit from new technologies and services


but it also identifies these threats:


•Reduced programmemaking spectrum

•Increased cost of spectrum

•Increased risk of interference


The issue is much more complex than the original poster indicates, but there is a certain grain of truth running there!


There is a similar problem in the US, where multinationals are clamouring to grab freed up spectrum....



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Just to add my 2p's worth - I think this could turn into a VERY costly exercise, for several reasons.


First off - the licensing authority will have a monopoly on proceedings, so they'll be able to charge what they like for the new licences. Whether this means that said charges become extortionate remains to be seen.


Next off - most small venues on un-licenced frequencies will not have received the letter referred above. Unless I've missed something here - what's the status of these frequencies? (I admit many of them will be VHF...) If they get wind of this then they'll want/have to buy new equipment in order to comply.


The thought also occurs that many people buying new systems might (for one reason or another) be completely ignorant of the fun and games to come, so manufacturers might end up profiting enormously from those buying the old and suddenly finding they need the new.


Unless they're feeling particularly helpful (and I'd love to hear from those who are), in the current market, the only emphasis on manufacturers to produce mics capable of using the new frequencies is for the industry purchasers to specify this capability. The fly in this ointment is that it may well be illegal to sell/use transmitters capable of using the new OR old frequencies.


Am I right in thinking that by "phased" changeover we mean that there will be a transitionary period, where both "old" and "new" frequencies are running side-by-side? If not, we could be faced with the problem that we won't be able to legally use or test the new frequencies until the old ones are turned off. If this is the case, then sales of the early models will be slow and the prices artificially high to reflect this.


The cynic in me can't help but wonder whether the government supports changeovers like this in a wider attempt to "stir the pot" and keep money changing hands. Whenever serious money continues to change hands, manufacturers cream the profits and the economy is temporarily propped up... Oh, and possibly the tax coffers too??


I just hope this series of changes doesn't translate into a move towards "licence exempt" radio systems transmitting in the 2.4GHz/5GHz range, which is getting noticably crowded already!!


I'll get me anorak... TAXI for Solstace!!!

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- most small venues on un-licenced frequencies will not have received the letter referred above. Unless I've missed something here - what's the status of these frequencies? (I admit many of them will be VHF...) If they get wind of this then they'll want/have to buy new equipment in order to comply.


The VHF deregulated band is not affected. However, the old frequencies between 173.8 and 175.0 have now been replaced with 173.8,174.00,174.2,174.4,174.6,174.8 & 175.00MHz. There is the potential for interference between old VHF systems and the new ones.


The UHF 863 - 865MHz deregulated band isn't affected by the proposed changes. Have a look at the presentation that JFMG gave at PLASA Look at slide 15 too see which TV bands will be affected.

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Granted most TV companies have more money than god and could go out tomorrow and get new wireless systems or the rental company supplying them will have to,


But as I see it, it would be quite funny if the TV companies buy the frequencies that they need to radio mics for presenters of TV shows! Mind you with some live TV shows, not being able to hear the "talent" would not be a bad thing.


Its complete madness, and life would be easier if we wait until digital technology and radio mics move on, when we have a better system that can be changed / updated after sales then would be the time to have a change over, granted time is not on our side and neither is common sense.



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I was talking to some of Sennheiser's radio mic folks a couple of months back who brought up a very good point - they don't think anything serious is going to happen until after the 2012 Olympics. The government would be seriously shooting themselves in the foot if they try to change anything before then.

I know when one of the last big games was on in this country a couple of years back they ran completely out of frequencies. They'll need even more in 2012 & I can't see the powers in charge being stupid enough to screw up the whole spectrum before such an important event and face international embarrassment. I might be wrong of course...

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I know when one of the last big games was on in this country a couple of years back they ran completely out of frequencies.


I'd expect the military to help here with temporary allocation of little used or unused spectrum. AFAIR, the Sydney Olympics had Australian Signal Corps provide spectrum and frequency management?



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