Digital Radio Mondiale (DRM)

Even shortwave is now going digital! This year, field trials of a new transmission method got under way, involving shortwave listeners and radio amateurs from all over the world. A ‘concept’ receiver was demonstrated at this year’s International Broadcasting Conference (IBC) in Amsterdam, and transmissions are officially scheduled to start in June 2003.The use of radio frequency bands below 30 MHz — long-, medium- and shortwave — has been in continuous decline over recent years. The main reason for this is poor sound quality. The channels used for programme transmission are very narrow: 9 kHz on mediumand longwave, 10 kHz on shortwave. Amplitude modulation, as used to date, is certainly technically very straightforward, but not very efficient. In particular, shortwave is very prone to interference. However, by using more sophisticated modulation schemes and modern data compression techniques it is possible to transmit ‘near-CD’ quality radio in this frequency band. Then the advantages of shortwave, its long range and lack of dependence on satellite operators or Internet service providers, come into their own.