The future of digital radio
What is DRM?
Digital Radio MondialeTM (DRM) is the universal, openly standardised digital broadcasting system for all broadcasting frequencies up to 174MHz, including LW, MW, SW, band I and II (FM band).
What are the benefits?
DRM is greener, clearer, wider, bigger, better quality & audio content and cost efficient
DRM provides digital sound quality and the ease-of-use that comes from digital radio, combined with a wealth of enhanced features: Surround Sound, Journaline text information, Slideshow, EPG, and data services.
The Digital Radio Mondiale (DRM) consortium was founded in 1998. Twenty organizations signed a Memorandum of Understanding in Guangzhou, China. These organizations represent broadcasters, academic institutions, and manufacturers. Its purpose is to develop a non-proprietary technical standard for the replacement of analogue AM (Amplitude Modulation) radio with digital radio, also called DRM.
International Telecommunications Union (ITU) 2002, International Electrotechnical Committee (IEC) 2003, and the European Telecommunications Standardisation Institute (ETSI) 2003, have all approved DRM broadcasts for frequencies below 30 MHz.
As a replacement for AM the existing channel spacing, medium and long wave 9 kHz and 10 kHz for short wave, is maintained. Audiences for AM radio have declined, most people will relate to the poor audio quality of AM music.
AM is inefficient in terms of spectrum usage as it requires twice the bandwidth to transmit audio as the same audio information is contained in both side bands. It is also inefficient in terms of transmitter power as 50% of the broadcast power goes into the ‘carrier’. It is not necessary to transmit the carrier although this complicates the receiver design slightly.
Radio amateurs gave up using AM many decades ago and use Single Side Band (SSB) or more accurately Single Side Band - Suppressed Carrier. Radio amateurs sometimes refer to AM as ‘Ancient Modulation’.
When receiving DRM any audio deterioration due to radio propagation fading or interference is not so evident compared to AM. Providing the DRM decoder software receives enough digital data correctly then it will be able to accurately rebuild the audio or data as it was originally coded at the transmitter.
Also the display of the name of the radio station, programme text, and automatic tuning to alternative frequencies will make DRM receivers easier to operate. DRM can also transmit multimedia pages and data
DRM Plus
While the initial version of DRM covers the broadcasting bands below 30 MHz, the DRM consortium voted in March 2005 to begin the process of extending the system to the VHF bands up to 108 MHz. DRM Plus (DRM+) will be the name of this technology.
On 31 August 2009, DRM+ has become an official broadcasting standard with the publication of the technical specification by the European Telecommunications Standards Institute; this is effectively a new release of the whole DRM spec with the additional mode permitting operation above 30 MHz up to 174 MHz.
Wider bandwidth channels are used, which allows radio stations to use higher bit rates, thus providing higher audio quality. A 100 kHz DRM+ channel has sufficient capacity to carry one low-definition 0.7 megabit/s wide mobile TV channel: it would be feasible to distribute mobile TV over DRM+ rather than DMB or DVB-H.
DRM Plus is now successfully tested in Band III, and this gives the DRM system the widest frequency usage; it can be used in band I, II and III. It is possible that DRM+ can co exist with DAB in band III.
