Long-range DRM digital Radio

The DRM System

DRM is an international digital radio standard that offers listeners noise free reception of long, medium and short-



waves worldwide up to 30 MHz. In addition to one or more stereo radio programmes, DRM radio can transmit textradio, graphics, photos and data. The system has been expanded with DRM+, which utilises frequencies above short waves to the FM band and beyond to 230 MHz. DRM radio is ETSI Standard ES 201 980 and recommended by the ITU.

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Digital Receivers

The long-range DRM world receivers in digital stereo are very popular and often include both DAB and FM capability.



In addition, they can also receive oldfashioned AM in mono, for example on medium waves. Operation is simple, and a knowledge of the programme frequencies is not required. Instead a list of DRM radio programme names is displayed, similar to DAB or digital tv. The price of a DRM radio receiver is presently from around 150 euros.

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Improved Reception

For weak stations the internal ferrite rod and telescopic aerials of receivers are insufficient and an external



aerial must be used. The cheapest solution is 10-12 metres of copper wire from the house to a tall tree, preferably with a transformer balun and a shielded feeder. If this is not possible, a loop aerial may be used succesfully indoors. Such aerials are available as individual components or kits, whereas active aerials are normally preassembled.

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Digital Broadcasting

It is possible to transmit radio digitally even on a small budget. DRM is non-proprietary with non-commercial software



of high quality for modulation, decoding, logging and coverage verification. Small linear transmitters up to 10-25 kW are well suited for DRM, whereas larger transmitters on medium- and especially longwaves require tuning of the aerial system. Shortwaves are unproblematic, and DRM is a low cost shortcut to feed remote FM radio transmitters.

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