Oops! Ha! OK, well err - you know what I mean

The original expansion plan was based on providing FM equivalence for a composite of both BBC local radio and ILR coverage. The maps used for this approach can be found here: http://stakeholders.ofcom.org.uk/con...planning/maps/

The current approach outlined by the DCMS doesn't attempt to go that far:


https://www.gov.uk/government/upload..._12_14__1_.pdf

The current plan is about joint funding and doesn't really provide a DSO route for BBC local radio, which the commercial operators probably don't want to fund.

Strictly speaking, the multiplex operator, Now Radio would be providing the funding. That said, it's worrying that Now Radio are applying to enlarge the digital licence area in both of these instances, without actually extending coverage into the expanded area.

BBC Radio Norfolk and BBC Wiltshire do provide FM coverage in these areas, so eventually DAB coverage will have to be provided to allow for a full DSO.

In an ideal world it would probably have been better to release a few more band III frequencies to DAB, introducing separate multiplexes in North / West Norfolk and in South Wiltshire. Giving a DSO path for KLFM, North Norfolk Radio and Spire FM and avoiding any requirement for Global to pay for carriage outside their primary service area.

Re Gloucestershire, in the three major Forest of Dean towns there is currently absolutely no local DAB coverage in Coleford; only a small amount of Cinderford can get local DAB, and in Lydney the High Street and surrounding streets in the middle of town have nothing. That's all based on driving around listening to my car radio - indoor coverage would be worse...
Two transmitters were originally planned (one in Coleford on the TV mast; the other on one of the various masts at Collafield outside Cinderford) now no sign of either. A significant part of Gloucestershire is being denied local DAB coverage.

As far as Gloucestershire is concerned, the existing DAB transmitter sites were considered to give composite FM equivalence. The additional 8 sites mentioned in the original proposal were to give "near universal coverage", not necessarily something that is commercially attractive. Cirencester already provided coverage in excess of the ILR FM equivalence currently proposed and the extended coverage from the Icomb Hill site has carried over to the latest plans. On the whole, Gloucester has done relatively well in the current proposals when compared with some other areas.

Icomb Hill was added, where there was previously no FM coverage from the local BBC station or ILR FM. By adding Icomb Hill to the Cirencester provision, that gave the Cotswold district council area two transmitters.
The Tewkesbury, Gloucester and Cheltenham council areas are well served by Churchdown Hill; and Stroud district council area by Stockend Wood.
That leaves the Forest of Dean council area without a transmitter. An area that has frequently felt itself to be geographically, economically and socially isolated from the other five councils in Gloucestershire. It no longer has its own community radio station, and only receives the local BBC station on old fashioned AM. There is a mast in Coleford carrying the TV for the town, so much of the infrastructure is there already in the main administrative town in the district for a DAB transmitter, that would provide a sense of inclusion for Foresters as they are so often left out.

Presumably, the multiplex operator has decided that it is commercially desirable to extend into these areas but not into others.


I don't disagree with what you are saying and there will be people in many other areas who feel the same. The point though is that the current DCMS/Ofcom DAB expansion plans only go as far as to provide FM equivalence with the largest ILR service in the region. For the Gloucestershire multiplex that requirement has been met and exceeded.

As you say, there wasn't an FM service in this area and there is no requirement in the current expansion plans to improve on the status quo. It remains to be seen what will happen if the DCMS eventually decides to turn off the medium wave transmitters.

Fine. So what's the plan for the large territories that are left unserved under the new agreement? Regional self-help minimuxes? Let's make the fairly plausible assumption that coverage outside the heritage ILR areas not envisaged in the 2016 plan will, in reality, never happen via the commercial route.

Thinking in particular about the Highlands west of Inverness, Argyll and the Western Isles, being part of the Inverness mux was always an irrelevance. However, having no local mux coverage at all means no Radio Scotland MW/DAB, where the sports are carried. Most of the region can receive at least something during the daytime from Burghead but this is impossible to listen to in the evening.

So does this confirmation that we're not going to get local DAB push us backwards to trying to convince Aunty to put in a TX for Radio Scotland and Radio 5 Live in the Highlands and Islands? The announcement that Radio Scotland would remain on MW starts to have more relevance all of a sudden.

We need to get the likes of Star Radio, Sun FM and NE1 onto DAB in the North East alongside the other stations.

As this is supposed to be a radio DSO, the current plan falls far short of achieving that requirement. The fact that digital licence areas, in England & Wales, are being expanded without adding coverage is interesting. It suggests that it is now up to the BBC to negotiate any further expansion needed to carry their local radio services. Probably with the funding burden falling largely, if not entirely, with the BBC. The lack of any similar expansion of digital licence areas in Scotland possibly indicates a different path. Perhaps planning for the future roadmap of DAB expansion in Scotland will be passed from the DCMS to the Scottish authorities. At the moment it is unclear.


The border areas aren't a major problem. Scottish Borders could work as an extension of Edinburgh, as originally planned. Dumfries and Galloway could be merged with Ayr and possibly extending Glasgow into South Lanarkshire.

Argyll & Bute could work as a northern extension to Glasgow. NW Scotland and the Western Isles is more of a problem. It is far too large an area to add to Inverness, a separate mux would make more sense. That raises the question of what services would actually be carried on the multiplex. A mux carrying only R Scotland and RnG would be wasteful of resources and, if the multiplex was funded by the licence fee, it would probably not be able to carry any commercial radio channels.


It's probably just an indication that arguments over funding are still holding back progress. The current plans don't give an indication of what will be done to further expand BBC coverage at a local level.

The ILRs with a relatively small coverage area aren't going to pay for carriage on the local DAB multiplexes which have a much larger footprint. For now, they are better suited to FM.

As small scale DAB is developed, we may start to see some of these services transferring to DAB, but that's not going to happen in the short term.

I've wondered what self-help DAB would look like. Satellite TV eventually killed many self-help TV relays, at DSO if not before. There are even more alternatives to DAB at home for radio listening than there are to DTT at home for TV viewing, which makes self-help DAB even less attractive. Still, there are limited options on the move, so who knows.

Am I right in thinking that it's a lot cheaper to build a self-help tx if there are frequencies to spare than if you have to re-broadcast on the same frequency? Are there many on-channel DAB repeaters out there? I only heard about one, in Nottingham I think, quite a while back. Is that still a very expensive technology?

Cheers,
David.

Apparently DAB 'repeaters' which compliment the rest of the service without breaking it have been technically worked out, meaning they would't have to shift frequencies. However, I can't see them being licensed for a few years.

It's already possible for shops to fit repeaters to allow DAB frequencies to penetrate their faraday cage warehouses.

Trials of single TX and multi-TX community radio scale DAB will happen soon on 11A.

Why? Ofcom have already demostrated a proof-of-concept and repeated coverage is one of the three scenarios proposed in the Small Scale DAB trial. So the repeaters are no further away from being licensed than the Raspberry Pi-based kit they have home-brewed for mux assembly, encoding and modulation forming the basis of the Small Scale trial
Those are more "amplifier-between-two-antennas" distributed antenna systems than proper repeaters. What Ofcom are envisaging to complement the Small Scale DAB TXs are proper active feedback cancellation units. These delay, decorrelate and cancel the RF picked up at the source antenna from the target zone antenna, getting 30-40 dB more isolation that spatial separation and screening alone.
The trial TXs won't be co-located with BBC national mux TXs, and will likely be in locations where BBC mux reception is below the -60dBm or so required to make a repeater solution work. So Ofcom have also developed a wheeze to receive the BBC ETI directly from satellite, re-broadcasting this over the same antenna as the Small Scale TX and thus closing the localised hole that would otherwise be 'punched' in the BBC mux. Again the guts is a Raspberry Pi, and there is a processing delay to RF of around 2 seconds longer than professional gear, so 12B can't be used. A local whitespace block is thus required for the BBC, in addition to the trial 11A block carrying the minimux.

Most of this post may seem off-topic in a local DAB rollout discussion, but the development by Ofcom of a very low-cost satellite-to-RF solution may ultimately make geographically-extensive minimuxes viable, when transmission OPEX to dozens of low-powered TX sites would otherwise have made such a project completely unviable. Regions like mine wouldn't have to be beholden to the Bauer's and Global's of this world and maybe local councils could give it a go themselves, given the right grant funding.

Do you have any more info on these trials as it all sounds rather interesting.

Kinda defeats the point of an SFN if every other town you drive into BBC National DAB is on a different frequency though...

Would using blocks 5A-6D as much as possible minimise those effects so much BBC National DAB won't need to be carried on the "wrong" frequency? (i.e. only in towns where the signal was already border line would the BBC be relayed as well). Presumably in the case of smaller towns using a high hill 2km outside of town (assuming suitable power supply etc) would mean those effected would be minimised even more?

My assumption was for no reason other than the perceived wheels at Ofcom turn slowly. I am quite 'excited' about the prospect of the PoC and the small scale DAB trials. If this helps community and smaller stations get on air, or even share a single block between them across 2 TX sites (e.g. East Grinstead and Uckfield could work nicely in terms of coverage if nothing else) then that's great.

But, I just can't see it happening for a while. I wish it would.

There's basic information on Ofcom's Small Scale DAB site: http://stakeholders.ofcom.org.uk/con...all-scale-dab/ but you had to be at the demos to see the goodies, in particular the off-satellite BBC mux translator. There may be a summary of the kit proposed by Ofcom somewhere online but I haven't loooked for it. Maybe someone else on here can help...
The Ofcom presentation only mentioned translating the Beeb mux at a single site, but by extension if you've got GPS available locking the minimux then it can provide absolute time and frequency information for the translated Beeb block as well. From that point, it's just a matter of selecting the kit so that the processing delay is as similar as possible and in theory you have a "poor man's SFN" via the back door of using the same translated frequency everywhere in the region to be covered.

This won't be as simple as it sounds, as you're probably talking about synching up a couple of Raspberry Pis to within one part in six - I don't even know whether there's an onboard adjustment for that or whether you'd have to give the system clock a kick every millisecond or so to bring it back into line with GPS-derived UTC? In any case, the fact that you'll only ever be in the coverage overlap between a couple of such minimux TXs makes synchronisation issues much less of a problem than with the Beeb, when you can easily be getting composite coverage from 7 or 8 TXs at some locations.

The small scale DAB trial has been expanded from 3 to 10 locations (this was one of the respondees' gripes) and is now being mentioned by DCMS and Ed Vaizey in the same press releases as the larger commercial local mux buildouts:


The fact that small scale DAB is being mentioned in the same breath as the existing local muxes and the new D2 service indicates that DCMS sees it as less experimental and more an adjunct to the 'big boys'.

As I said in an earlier thread about small scale dab, why reinvent the wheel, much of the groundwork has already been done both here and in Europe. Ed Vaizey probably read it on here.

This local DAB could give all of the small radio stations a another slot to do experiment radio on, They won't be able to do that on there main station slot.

Guess so, provided any "experimental" services also complied with the terms of their broadcasting licence. A more interesting question would be, would minimux services launched by a community station over-and-above their FM (or AM) stream have to comply with their key commitments?


AIUI, the technical proof-of-concept has already been done several times. Ofcom even had all the kit working on a tabletop at their demos.

What they're trying to establish with the trials is how well local groups can build a mux comprising a variety of audio services. In the 'death-threats-and-crushes' world of community radio, this may be far more difficult than connecting the bits together and getting them to work.

With the final confirmation that 'local DAB rollout' is to be little more than digitalisation of existing main ILR coverage areas, it leaves something else to try to put colour on the remaining white bits of the map. Local minimuxes, as imperfect as they are, might be it.

Maybe it's a sign of getting old but these things just seem to take so long to get done and will no doubt be over regulated and too expensive.

We need more like this, fm & community dab with a homebrew transmitter.

http://www.heimers.ch/de/vhfamp.html

That's where the government regulation is going to come into it isn't it?

Take a look at something like Gaydio or Angel Radio - community stations with national ambitions - would there DAB outlet need to be the same as analogue, would they be allowed opt outs etc?

Also, who's allowed the licences?

Take Nottingham for instance - a local multiplex consisting of Kemet, Faza, and Dawn is a pretty obvious and logical choice - adding the student stations of URN, Fly FM, Radio Norman is pretty obvious and sensible extension of that too, even something like NGenious (an online only station playing local new music), and arguably BBC Radio Nottingham opt-outs should be welcome too. But what if we ended up with Heart 80s, Heart 90s, Heart 00s, Heart 10s, Smooth 60s, Smooth 70s, Classic FM Xtra, LBC News, Xfm 90s and the like filling up mini-muxes up and down the country?

If you licence a minimux for Preston which has just Preston FM and The Bee on it, and then The Bee migrates to the Lancashire multiplex, and Preston FM closes down could the multiplex carry on with just a load of Bauer extra stations? If yeah, could Bauer then go and launch a mini-mux of their own in Blackpool and Central London with no community stations on it? What if Bauer had Rock FM 4 on all the mini-muxes in Lancashire and the same thing happened in Preston - would that city now need to loose that service, or would Bauer be forced to move it to the Lancs multiplex increasing costs for the stations in Blackburn, Wigan et al where they were also broadcasting?

Saying a company is only allowed on one multiplex then rules out some small scale ILR and community stations (think BFBS, Angel Radio, UTV and UKRD's networks), and also some stations which could play an important community role (think The Wireless, Angel Radio, Gaydio) even if they are a bit more national in scope. Indeed allowing some of these more-niche broadcasters national coverage via the minimuxes, which could work like the Freeview local multiplexes and bring in valuable extra income.

The regulations and how the organisations work together seems to be a much bigger part of the challenge here with the minimuxes than the technical aspect.

For south west Oxfordshire membury is already an existing tx site for d1 and wilts local multiplex

Matching the same number of people covered by commercial local radio is how this is being sold - i.e. 91% population coverage. Not ensuring everyone which could get it on FM gets it on DAB (i.e. some areas may be worse, but they will be balanced by those which are better).

The switchover targets have always mentioned commercial ILR coverage haven't they?