Software defined radio allows the benefits of digital radio modiale to bootstrap the fortunes of digital audio broadcasting, according to John Hall of RadioScape

Digital audio broadcasting (DAB) has been a tremendous success story in the UK but few other countries have managed to be anywhere near as successful, despite having rolled out extensive broadcasting coverage.

The appearance of digital radio mondiale (DRM) is viewed by some as being the death blow for DAB. In fact, nothing could be further from the truth. DRM could be a Trojan horse that will revitalise DAB in many countries.

The main reason why DAB has failed to take off outside the UK is because, in many countries, the DAB broadcasts are the same as the existing FM ones – often a condition imposed by legislators. The UK realised early on that people would not buy a new radio just for a marginally better sound quality. They will, however, buy a new DAB radio if it is the only way to receive programmes that they cannot hear on their existing analogue receiver. 

John Hall

The BBC pioneered the broadcasting of differentiated DAB content creating the demand from customers that is being met with dozens of different radio designs available in UK shops. They have been joined by dozens of DAB-only stations resulting in the UK now having more DAB stations than those broadcasting on analogue FM, offering greater variety and content for listeners. 

By contrast, in other countries that just simulcast their existing FM programming, there is little incentive for customers to buy DAB radios. The retailers therefore do not stock them and the broadcasters can see no reason to put effort and money into creating differentiated DAB programmes for which there is no audience and no advertising revenue to be had.

Some people believe that this DAB problem is further exacerbated by the arrival of DRM on the premise that, as a newer digital radio technology, it is therefore bound to be better and will replace DAB.

However, the DRM business model is based on a substantially different premise. DRM uses digital technology to bring FM-like quality to short, medium and long wave AM broadcasts. These can have a much greater ranges than DAB with many fewer transmitters. For example, a single transmitter can broadcast across an entire continent.

This opens up the possibility for whole new business models. For example, Europe’s biggest commercial broadcaster, RTL Group, plans to use DRM for new country-wide stations for France and Germany and a service targeting the UK under the relaunched and legendary “Radio Luxembourg” brand.

Existing regulations and lack of spectrum availability in FM preclude the creation of such services but, because DRM can reuse existing AM spectrum and can be broadcast with excellent audio quality from one country to another – even from one continent to another, these problems can be sidestepped.

Many major broadcasters are implementing new services for Europe based on DRM and are gearing up for a massive publicity campaign to support the take up of DRM by listeners. Over 70 broadcasters from all over the world are already on air, with both the quantity and reach of these broadcasts set to mushroom year on year.

The other part of the business model that makes DRM compelling for broadcasters is the re-use of existing AM allocations and infrastructure. For many broadcasters, listenership on analogue has dwindled in the last few years to the point where many have even considered ceasing services. Most existing infrastructure can be upgraded relatively cheaply and power requirements to create the same coverage or “footprint” as existing analogue services can be up to 40 per cent less, thereby minimising the costs and maximising the opportunity of going digital for many AM broadcasters.

As for additional compelling content, the AM bands offer the possibility of many new broadcasting stations as these are currently under utilised or lapsed and local and community services, which are traditionally run on analogue MW could get a new lease of life by being digitised. The scope is huge.

So if DRM is so great, won’t DAB just die off completely? In fact, the business models for the two digital radio systems are complimentary not conflicting. One key reason is the difference in their broadcast range. Another is that DAB has much higher bit rates which enables it to deliver many innovative services based on  broadcast data and video, plus, of course, it already has infrastructure and services in place in many countries.

So, the two standards can coexist and overall the listeners get more content, and more differentiated listening experiences.

There is one problem today, however. DRM receivers are currently few and far between and very expensive – essentially at the same stage that DAB receivers were several years ago. Fortunately, as DAB and DRM share many similar characteristics, it is entirely possible to add DRM capability to DAB receivers without too much additional cost, especially if one uses a “software defined” radio approach.

Software defined radios use standard DSP chips to do the baseband decoding; these run software that tells them what kind of service they are to decode, e.g. DAB, analogue FM or AM, or indeed now DRM. Essentially all that is required in addition to the software is a new RF “front end” capable of receiving the off-air signal.

This approach means that DRM-capable, multi-standard receivers can be brought to market very quickly. Thanks to the benefits of mass production of DAB radios, which are already shipping to the UK market, these DRM-capable DAB radios will be able to be brought to market at competitive consumer prices not only for the UK but for the rest of the world.

So we will soon have the situation where the world has multi-standard, digital radios that can receive DRM, DAB Band III and L-band, RDS, FM, AM, LW and MW. This will become the new norm for radios. No longer will people have to remember the frequency or band that are broadcast on. Instead the receivers display the station name so that people select by programme - the technology to deliver it becomes transparent.

This is the Trojan horse effect. By buying multi-standard radio receivers, households will have the capability to listen to DAB as well as DRM. Suddenly the broadcasters have growing audiences available to them and the spiral is broken.

The UK model shows that broadcasters can make money by using DAB for local services and to provide a wide variety of content. The floodgates are now set to open for DAB to take off in a big way around the rest of the world - thanks to DRM.

John Hall is the CEO of Radioscape

www.radioscape.com