Also known as: DRM, Digital Radio Mondiale, DRM30, DRM+
Overview
Digital Radio Mondiale (DRM) is an open ETSI standard for digital broadcasting in the same long-, medium-, and short-wave bands historically used by AM, designed to deliver clear, near-FM-quality audio within a conventional ~10 kHz AM channel.1 It replaces the analog AM envelope with a coded OFDM waveform (COFDM), so the same shortwave slot that once carried noisy AM can carry a robust digital stream — plus text and station data — that either locks cleanly or drops out, with little of AM’s gradual fade. The DRM30 profile covers the AM bands below 30 MHz; the later DRM+ profile extends the system into VHF up to about 174 MHz.
Technical characteristics
| Property | Value |
|---|---|
| Waveform | COFDM, four robustness modes (A–D) for worsening channels |
| Subcarrier modulation | 4-QAM, 16-QAM, or 64-QAM per service needs |
| Channel width | 4.5–20 kHz (DRM30); ~100 kHz for DRM+ in VHF |
| Bands | LW/MW/SW below 30 MHz (DRM30); VHF to ~174 MHz (DRM+) |
| Audio codec | xHE-AAC today (originally HE-AAC, CELP, HVXC) |
| Error control | Multi-level coding with interleaving |
| Data | Text messages, station labels, and a small data service |
History
DRM was developed by the DRM Consortium — broadcasters, manufacturers, and research bodies — and first standardised by ETSI as ES 201 980 in 2003, with regular international transmissions beginning that year. DRM+ (Mode E) added VHF operation later in the decade, and the audio codec was modernised to xHE-AAC to improve quality at the very low bit rates the HF channel allows. Adoption has been gradual, concentrated in a handful of national broadcasters and notably in India’s medium-wave rollout.
Deployment
DRM sees real but limited use, most prominently in India, with intermittent international shortwave services elsewhere. Its promise — full AM-band coverage with digital clarity and lower transmitter power than analog AM — competes against the reality of a huge analog receiver base and modest consumer hardware availability, so it supplements rather than replaces AM on most of the globe.
Decoding it with GopherTrunk
GopherTrunk does not decode DRM; it is a VHF/UHF trunked land-mobile scanner and DRM is an HF/MW/VHF broadcast mode outside its scope. DRM is nonetheless a good illustration for GT readers of coded OFDM surviving a hostile fading channel, and open-source software (such as Dream) can decode a DRM broadcast from the baseband of an HF-capable SDR.
Sources
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Digital Radio Mondiale — Wikipedia, for the AM-band digital standard, COFDM waveform with QAM subcarriers, the DRM30/DRM+ profiles and channel widths, and the xHE-AAC audio codec. ↩