DRM+ is the enhanced version of the Digital Radio Mondiale (DRM) standard. Whereas DRM30 is designed as an open digital radio standard for the long-, short- and medium-wave broadcasting in bands below 30 MHz, DRM+ is designed to cover the spectrum from 30 MHz up to 174 MHz, which includes the standard FM band. DRM+ allows broadcasters to deliver CD quality audio at datarates from 35 kbps to 185 kbps, at signal-to-noise ratios of 2 dB to 14 dB.
DRM+ is built on the DRM30 system, making use of a similar OFDM design with new parameters, the same audio codecs and the same multiplex and signaling scheme. It can even support MPEG Surround stereo-compatible 5.1 broadcasting.
To date, the DRM+ standard has been approved by the European Telecommunications Standards Institute (ETSI), which had previously approved the DRM30 standard. This approval comes as no surprise to Hal Kneller, market development manager for Nautel, maker of DRM transmitters.
“Since DRM+ is an extension of an existing standard, it is not like it is a totally new system,” he said. “The same modulation techniques and codec are used as in DRM30, but obviously, much more bandwidth is available.”
DRM+ is more than just a digital version of FM radio. Like DRM, upon which it is based, DRM+ can support up to four audio services or a single compressed video feed on a single channel. For FM broadcasters, this is a powerful and potentially money-making combination.
But that’s not all: DRM30 and DRM+ receivers can receive substantial amounts of data over the air, which means listeners can download and use an electronic program guide (EPG) rather than twiddling a tuning knob. The EPG lets listeners tune by genre, program name, station or frequency.
The DRM/DRM+ receiver’s LCD screen can also supply information about the station and the music being played; much like RDS does today, but with much more content and the ability to show graphics too.
DRM+’s capabilities were first publicly demonstrated in Paris on 16 July 2009. The test signal was broadcast in VHF band I on 64.5 MHz from the Tour Pleyel. Located in the commune of Saint-Denis in northern Paris, the Tour Pleyel is a skyscraper whose antenna tops 143 meters.
The first DRM+ signal carried both stereo and 5.1 Surround sound audio, plus digital images. Reception was achieved successfully using fixed and mobile (car-based) receivers.
DRM+ signals were subsequently transmitted and received in Hannover, Germany, on 19 August 2009 during a broadcaster meeting organized by broadcast regulator Niedersächsische Landesmedienanstalt (NLM) and Institute for Communications Technology (IKT) at Leibniz Universität Hannover.
In early 2010, Brazil began testing DRM+ on FM in Belo Horizonte and São Paulo. The tests are being conducted by the Ministry of Communications in partnership with other federal and state agencies and several universities.
Where Are the Receivers? DRM30 works beautifully; especially on shortwave. Now if only there were some low-cost DRM receivers available.
Prices advertised online for the few commercially available receivers range from €99 for a Morphy Richards DAB/DRM Radio 27024 to €199 for a Himalaya DRM-2009 DAB/DRM/AM/FM receiver to €236 for a UniWave Di-Wave 100 DRM LW/MW/shortwave and analog FM unit.
“DRM Consortium members Sony and Sangean have really fumbled the ball on this one in the matter of receiver production,” says Radio Australia Transmissions Manager Nigel Homes. “Sangean in particular we expected to produce an efficient DRM receiver to put in their stable of DAB/DAB+ products.”
“Until there are more DRM receivers out there, I don’t think any more stations are going to add DRM services,” said Jeff White; owner of U.S. commercial shortwave station Radio Miami International, president of the U.S. National Association of Shortwave Broadcasters and member of the DRM-USA Steering Committee. “It truly is a chicken-and-egg conundrum.”
The obvious market for DRM receivers is shortwave, where analog sound and signal quality are constant problems. Unfortunately, DRM was “conceived just after the end of the Cold War,” said Andy Sennitt; shortwave expert and editor in charge of Radio Netherlands’ “Media Network” blog. “By the time the DRM30 technical standard had been finalized, a clear trend had developed where the receiver companies could see that shortwave was going out of fashion in many parts of the world,” he said.
Today, shortwave radio is seen as appealing primarily to Third World listeners, who can only afford the cheapest of receivers. But this stereotype is misinformed, said DRM Consortium Chair Ruxandra Obreja.
“India has committed itself to the DRM standard, and there are at least 300 million people who belong to the middle class there,” said Obreja. “300 million is the same as the population of the entire United States. These are people who buy TVs and computers and cellphones, so they won’t wait for a DRM receiver to become cheap before buying it — but only if they see a good reason to do so.”
For her part, Obreja sees consumer ignorance as DRM’s biggest obstacle.“Consumers are not aware of the many value-added interactive features that DRM radio can deliver, nor do they have access to unique DRM-only content that would make them want to use this medium,” she said. “To change things around, we have to do our homework, and the broadcasters have got to create DRM-only content that people really want.”
— James Careless On 10 February 2010, DRM+ tests began in VHF band III in Kaiserslautern, in southwestern Germany. Staged by the Landeszentrale für Medien und Kommunikation (LMK), the broadcast regulator for Rheinland-Pfalz, and Technische Universität Kaiserslautern, these signals are being broadcast on a 100 W DRM+ transmitter.
Where Does DRM+ Fit In?
Like DRM30, DRM+ has been proven to be a robust digital radio standard. But unlike DRM30, DRM+ doesn’t have the same obvious fit for broadcasters.
The reason: DRM30 was designed to provide near-FM quality on frequencies below 30 MHz; currently dogged by poor quality audio and transmission fading issues in analog mode; especially on shortwave. Currently, DRM30 is the only digital alternative for shortwave and longwave; iBiquity’s HD Radio AM and DRM30 both operate on medium-wave. At present, many shortwave broadcasters are offering DRM transmissions. However, there are few DRM radios available, and those that can be purchased are expensive.
In contrast, DRM+ competes with the European DAB/DAB+ standard, which has already implemented on-air in many countries. Meanwhile, the U.S. is pushing ahead with deploying HD Radio on FM and AM.
Given current investments in other digital radio technologies, questions remain about how many broadcasters in these respective regions would be willing to consider employ DRM+ or DRM30 as an alternative or supplementary digital system.
A case in point: The Australian Broadcasting Corp. (ABC) “sees DAB+ as the primary platform for digital radio in this country,” said Russell Stendell, ABC Radio’s head of technology and digital radio planning. But that’s for urban areas covered by FM. Remote areas in the interior have to be served using a network of 50 kW medium-wave transmitters, which don’t offer the necessary bandwidth for DAB.
“Consequently, our view is that, if there is to be a full digitization of radio at some stage, a supplementary platform such as DRM30 would be required to address extended coverage issues for our local services in regional and remote areas,” said Stendell. “I’d see DRM+ as a longer term thing too. We have requested that spectrum be reserved for it in band II after the analog TV switch-off but, as with DRM, I’d see DAB+ as the primary platform with DRM+ supplementing coverage in some area.”
Hal Kneller agrees that DRM+ and HD Radio are “competing and different ways of arriving at a similar solution” he said. But Kneller sees DRM+ and DAB as different, because they operate in different bands. As a result, both systems “can be complementary to each other,” Kneller argues.
“For instance, some private broadcasters in Europe (specifically Switzerland and Germany) were not interested in participating in the DAB+ multiplex. They preferred an approach to digitize on the FM band. We could also see small cities, that do not have need for a costly multiplex with only a few channels, using HD Radio or DRM+ due to the efficiencies,” he said.