As everyone should be aware (and shame on those industry types who don't), next year see's the final stages of DSO (
Digital Switchover) in the UK. For our industry this means the loss of the radio frequency that we use our radio microphones on - CH69, and a move to CH38.
First, let me just clarify a couple of points about the current (pre-DSO) use of radios...
JFMG are the people in charge of the radio use for PSME (Programme Making and Special Events).
The current PMSE standard license is for 13 spot frequencies between 854.900MHz and 861.750MHz.
ALL USERS SHARE THIS SPACE - WITHOUT PRIORITY. So, if you have four frequencies at a conference, and another meeting next door has the same, it is up to the two sound-blokes to negotiate who's going to use what. Of course, if the bloke next door hasn't bothered to get a license, you can tell him to sod off, and if you're really mean, report him...
'I just need some space, OK?'
Users needing more space can license, with JFMG, other frequencies for a minimum of 48hrs in frequencies lower than this, as long as you know where you are going to be in the UK. For most of the TV band this is £8.50 per frequency.
'I'm cheap...'
Finally, there is also a bit of spectrum called CH70 which is completely de-regulated. Anyone can use it for anything. ANYTHING. That's 863 to 865MHz. Again A N Y T H I N G!
So what does all this mean to the guy with the mic? Well, in the real world, most small conferences use 8 to 12 wireless microphones. Which, interference-free, would pretty much fit somewhere in the CH69 with a little help from CH70 (if you must) and very very occasionally a bit of the top of CH68. Not too bad if you're the only conference in the building, and you're not in central London.
Now, I think at this point I should point out a couple points about the radio microphone equipment we use. The units are not made to only work on the frequencies that are listed in CH69 ('cause you might want to get a license for some of that other spectrum?), and finding your frequencies can sometimes be a bit of a black-art. If you want to bore yourself to death about inter-modulation, do so here:
http://broadcastengineering.com/newsrooms/broadcasting_wireless_microphones_frequency/
OK. So, what next?
Well, as I said, we're all moving down to CH38, and users with a license from JFMG have automatically had CH38 added to their license (606.100 to 613.900), and from next year these will be the only frequency you can use, without an additional license.
EXCEPT - CH70, which will remain de-regulated and free to use for ANYTHING. (Why do I keep putting anything in capitals? Well, it's worth reminding ourselves that this means anything by anyone, and not just radio mic users. Kids toys, 'walkie-talkies', remote control cars - although these are usually down in VHF - you can use mics down there too if you like...)
So, back to the point. How many channels can you get in CH38?
Well, now it gets tricky. Shure say 10 (if you push for an answer), MIPRO say eight, Sennheiser won't say! However, all of them are selling systems with tag lines claiming 16+ channels inter-mod free.
Let's take MIPRO. We love them, and we use them. We also sell them, do give us a call.
They can squeeze eight channels inter-modulation free in to CH38.
They also have a standard plot for 16 channels, split across two bands with different transmitters (soon there will be a single wide-band version). Anyway, to achieve these 16 channels, you really need to head up as far as at least 640.500MHz - well into CH42. So you're going to need to get a least eight temporary licenses (as above from JFMG) for the additional bandwidth. And that is EVERY TIME you use them. Hire rates for radios is going to go up a bit, no?
'There's just one thing that bothers me...'
We've already talked about getting licenses for extra frequencies, both pre and post DSO. But what does this really really mean to the user? Well at the moment your more than likely sharing those frequencies with analogue TV. This has always been the case, and radio mics have generally always worked. Great. However, the frequencies above we have looked at for extending our new CH38 system, isn't going to be analogue TV from DSO, that's sort of the point of DSO! So, will those little 10-50mW packs stand up to a big fat band-efficient digital TV broadcast full of 0's & 1's? Who knows? I would say, that in the real world, the black art of radio-plotting will become a whole load harder. (Take a look at the the article I mentioned above, and look at
fig.3)
'Is that a light at the end of the tunnel?'
I think there is. The phrase, if you can't beat them - join them springs to mind. And in that vein, RP is looking into going Digital. No coincidence that MIPRO has a rather tasty and well-proven Digital Radio Microphone system up and running and ready for use in the UK.
You might ask 'what bloody frequencies do they use then?'. Simple, the same as that nasty digital TV I'm so scared of. BUT, because the radio's are also using a digital signal, we've negated all the possible problems of inter-mod. Yes, you will ALWAYS have to buy spot frequencies, but you'll also know that they will work. And, it's a premium product, full of features such as 128 encryption (meaning no-one with a cheap receiver can 'listen-in' to your mics.).
This sound engineer likes the sound of knowing he hasn't to worry about spending his gigs worrying about dropouts...
Finally.
Although the 'science' works anywhere the frequencies don't. Many European Countries don't have a JFMG to manage spectrum. In Ireland you just have to find a frequency that works. In others, you have to share with the Military, and can get in to a heap of trouble if you use their space without permission.
Oh, and give it five years and it'll be all change again...
DISCLAIMER.
Right, usual stuff, this is much opinion, I'm not a scientist, just a sound-man in the real world.
Don't take my word for it, look around the internet and forums.
Stay legal. I suspect that there will be much much more 'Radio Police' about in the future, and you don't want to have to explain to your client why you can't use the radio microphones.
