dab digital radio radio

Digital Britain has arrived (or is at least en-route)

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So here’s my brief contribution to the flurry of analysis of Lord Carter’s Digital Britain report.

The biggest news is that we get a target date for switchoff (sorry, “Digital Upgrade”). 2015 is the year we should be flipping the OFF switch on (almost all) analogue radio, and offering universal coverage of DAB. That date can now be plugged into business plans, and financial projections, and hopefully provide the necessary laxative effect to the recently sluggish developments around DAB in the UK.

So, rather than dissect all of the Radio section of the report, which others will do better than I, here are the bits I particularly noted:

It’s a full switch-off (“upgrade”)

Some summaries have suggested that the 2015 deadline only applies to national radio. It doesn’t – it applies to all services being carried on both national and local multiplexes (3b.10). The only thing left on FM post 2015 will be very small scale services; either commercial or community. There is not going to be a dual-speed changeover, which leaves local radio dragging along for years with a foot on each platform. That’s good.

Support for WorldDMB Profile 1

There it is, snuck away in 3b.20 – receivers sold in the UK should be at least WorldDMB Profile 1 compliant. The box on the following page is a little more explicit in saying that we are giving ourselves a migration path to DAB+, which is the smart thing to do. Nobody seriously considers DMB-A (the Frankenstein bodge invented to make an ill-informed decision seem at least slightly less ridiculous) for radio, so let’s ignore that. Some commentators have, incorrectly, said that Profile 1 includes DRM. It doesn’t, and DRM needs to mature a great deal more before it can earn a guaranteed place alongside DAB and DAB+.

Improving Signal Quality

It’s no secret that I don’t believe DAB should be crippled by being forced into universally super-serving a small fragment of the audience that expects ultra-high-quality audio from every radio station. The market can and will decide what audio quality is right for which stations and bearers.

But I do believe that we need to offer robust indoor and handheld coverage to everyone who currently enjoys that from FM now, and by crikey, it’s not rocket science to do it. Australia’s got the right idea – power. And more of it.

There’s some more crypticness in the report. It talks a lot about achieving equivalent coverage prior to 2015, but only in 3b.23 does it explicitly recognise that indoor coverage must be more effective. It also recognises that there’s some cost in achieving network upgrades, but notes that there is opportunity for negotiation between the BBC, multiplex operators and transmission providers. That’s timely, as many of the initial multiplex transmission contracts come up for renewal soon, and knowing with certainty that it’s worth spending money on the infrastructure is very valuable.

Replanning the network

This wasn’t as explict as I had hoped for. There is reference in 3b.26 to giving OFCOM the powers to re-plan and amlgamate multiplex areas, but I would really would like to have seen a more definite commitment to re-plan at a spectrum level to get a step-change in coverage (up) and costs (down). At least there’s a statement that sorting out coverage shouldn’t be as expensive as some people might have made out it could be.

And now – drum roll – the best bit…

In fact, it’s so good, it’s the only bit I’m going to quote verbatim from 3b.31:

Functionality and interactivity must become central to the DAB experience.
EPGs, slideshows, downloading music, as well as pause and rewinding live radio
must be developed and brought to market on a large scale. Broadcasters and
manufacturers must seek to develop and implement digitally delivered in-car
content, such as traffic and travel information.

Well, we waited a decade, and now it’s a formal part of the plan to digitisation. Digital Radio must prove its worth by doing something… digital. If we don’t use the platform and spectrum we’ve been given (and will continue to get for free for a while – 3b. 27) to evolve radio, what’s the point of doing it? Same value, different platform?

If the other parts of Digital Britain are designed to create confidence in building transmission infrastructure, and writing long-term financial plans that support transitionary investment to achieve that, then this is the statement that should create the confidence in investing in a new kind of digital radio, and it’s about a content led experience that’s enabled by a universal, free-to-air technology. If the rest of the report stabilises the ship, and gives it a shove in the right direction, this is the bit that signals the start of true innovation and digital change for radio.

7 replies on “Digital Britain has arrived (or is at least en-route)”

I would have liked to see more committment to use of DRM in the digital universe. It needs more coordinated planning for the digital replacement on the MF anf HF [AM] bands at this stage if receiver makers are going to get it right with multi-systems DSP decoder chips in one go covering DRM, DAB+ and the US Sirus satellite [and others ] for direct sat` reception possibilities.

Also, I am not totally convinced that your suggestion that the broacaster will decide the best bandwidth for their respective speech/music output platforms. I would suspect that DAB audio quality will, in the main, suffer a considerable downgrade to that we currently have come to value with Vhf FM.
David Prewett

Fully with you on 3b.31 Nick, I seem to remember you saw my slideshow demo in Sydney a few years ago. I found that once the concept was off paper and a real demo it became quite compelling and worked much better than Broadcast Website.

We are dicussing a Re-Launch of DAB with DAB+ in Germany.

The DAB Modulation is a very old (first) digiltal modulation technology.
Better effiency may be reached by DVB-T2 i.e. (near to Shannon)
A DVB-T2 modulated Transmitter would need 10 dB less power to cover the same DAB area with same data rate.

What do you think about this fact (having Germany in mind).

Hello Rabu – danke für Ihre Anmerkung.

It’s true that DVB-T2 can achieve a very high information density, but there are a number of tradeoffs. Firstly I’m not sure that the power levels you mention would provide an adequate C/N (signal to noise) on a mobile receiver without a directional antenna. DVB-T2 is intended to provide signal to TV antennae, mounted on roofs, which have high noise rejection. I also wonder if it will be able to provide sufficient rejection of multi-path signals, and cope with the Doppler effects of moving vehicles? DVB-T2 is also a wide bandwidth technology, which means it will be power-hungry to decode, which would have an impact on battery powered devices.

COFDM, on which DAB and DAB+ are based, is very rugged and robust, and provides quite high information density. Admittedly, MPEG2 is not the best codec in terms of quality/bit ratio, and no country taking DAB on now would use MPEG2. The combination of HE AAC v2 and Reed Solomon Coding (and Fire code) makes the DAB+ signal very robust and very information dense – two important qualities when talking about a mobile medium. The bandwidth is appropriate – about right for a battery powered handheld device, and it can be delivered in Band III in 1.7 MHz channelisations, which is quite spectrum efficient. At Band III, the signals have propagation characteristics similar to existing Band II (FM/UKW) signals. Moving to UHF changes those, the network design and the power efficiency of transmission, quite a lot.

There is no perfect technology, and we should also consider things outside of technology.

DVB-T2 is just being designed now, and there are no real-world deployments. There are certainly no handheld receivers, or kitchen radios, or car radios for DVB-T2. A DVB-T2 receiver will be complex, and expensive. Sure, if you wait long enough, some of that will change.

DAB+ is working now. The technology works, there are lots of receivers available and they are at good prices. There is also the basis of a DAB+ network already in existence in Germany.

I sometimes explain it like this. If you buy a computer today, there will be a better computer in a year from now. You could buy the best computer you can now, and it might last 10 years (my Dell 8200 at home is 8 years old). Or you can keep waiting and waiting for a “better” computer. The problem is, if you keep waiting, you find one day that all your friends are on Facebook and Twitter and E-mail, and you are still using a chisel and a piece of stone.

Dear Nick,
Thank You very well for your extensive remarks.
I would like to carry on in two steps:
The first step is regarding T2 performance.
DVB-T2 will be the most efficient digital modulation we have actually.
T2 is designed to work with several Bandwiths. One of them is 1,7 MHz.
You are right that T2 can povide very information density (until 45 MBit/s in 8 MHz Channel). But even very robust modes are possible like QPSK CR 1/2 with a C/N of 3 dB under mobile reception conditions. That means almost 10 dB higher sensitivity as DMB.
The net data rate in this mode is arround 1,2 MBit/s.
Assuming the same C/N as needed for DMB an Net data rate of 4 Mbit/s in a 1,7 MHz would be possible (+300% of DMB).

FYI: first Modulators and silicon-chip receiver ar available. I guest we will see a lot of T2-receiver at the early 2010.
(please excuse my poor english)

Theoretically, DVB-T2 is capable of many things, and it’s a clever technology designed by clever technologists. But it is a very long way from being deployed in the field, and a field deployment will change the real coverage and performance it achieves. Even if silicon is available, there are many other questions to be asked. Who will build the network? Will it be affordable for radio? Will anyone run it in 1.7MHz channelisations? Will anyone build radios? How much will those radios cost? What data services will it support?

The requirements for television are *different* to radio, so it’s dangerous for radio to assume a television platform will meet its requirements. There is always a new technology to explore, and a new concept being thought of. That’s not the same as having a system that’s proven to work, and that has lots of receivers, and has them at the right prices for consumers.

I’m sure DVB-T2 will be good for television. I know some people working on the project, in both transmission and for television set-top-box and integrated receivers, and they are fine technologists. But none of them think they are developing a system for digital radio.

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