Global Designer: Multistandard software-defined-radio adds DRM format

DRM (Digital Radio Mondiale), a proposed standard for digital radio, enables broadcasters to reuse frequencies below 30 MHz as progressively smaller audiences are listening to the conventional services, including AM, long wave, and short wave, in which the band operates. DRM uses compressed audio and digital QAM (quadrature-amplitude modulation) to achieve robust transmission and reception with added service features.

Broadcasters can achieve extended coverage—in some cases, continentwide—with the same power that previously covered a more limited area. Alternatively, they can cover the same geography with reduced power and can package multiple channels in the same spectrum allocation. An additional attraction for operators is that using the frequency often requires only a modest upgrade to transmitters. Depending on the data rate and codec they use, they can achieve near-FM quality. Many broadcasters are already experimenting with transmissions.

Now, RadioScape, which has for some time produced modules to receive DAB (digital-audio broadcasting), has introduced the RS500 module that adds DRM to DAB; FM/RDS (radio-data service); and long-, medium-, and short-wave radio. This module includes the same features as the earlier RS300 module, forming the core of a complete digital radio with pause, rewind, and record to an MMC memory card, plus full access to electronic-program-guide data. DRM permits features such as frequency shifts, in which the broadcaster moves the transmission between allocated frequencies in the course of a day to cope with the variable nature of propagation below 30 MHz, enabling receivers to track the channel shifts. RadioScape recently changed its profile to be a manufacturer of complete modules rather than a supplier of silicon and provider of licensed module designs.

RadioScape, www.radioscape.com.

Digital Radio Mondiale, www.drm.org.