Also known as: DAB, DAB+, Digital Audio Broadcasting, Eureka 147
Overview
Digital Audio Broadcasting (DAB) is a terrestrial digital radio standard, developed under the European Eureka-147 project, that replaces one FM station per channel with a multiplexed ensemble of many stations sharing a single ~1.5 MHz block in VHF Band III.1 It transmits with coded OFDM using π/4-DQPSK on each subcarrier, making it robust against the multipath that plagues wideband signals in mobile reception. The upgraded DAB+ profile keeps the same air interface but swaps the original MP2 audio codec for the far more efficient HE-AAC v2, roughly tripling the number of stations a multiplex can hold.
Technical characteristics
| Property | Value |
|---|---|
| Waveform | Coded OFDM (COFDM), multiple transmission modes |
| Subcarrier modulation | π/4-DQPSK (differential, no channel equaliser needed) |
| Block width | ~1.537 MHz (Mode I: 1536 subcarriers) |
| Bands | VHF Band III (~174–240 MHz); historically L-band |
| Audio | MP2 (DAB) or HE-AAC v2 (DAB+) |
| Error control | Convolutional coding; Reed–Solomon added in DAB+ |
| Network | Supports single-frequency networks (SFN) |
History
Eureka-147 research began in the late 1980s, and DAB launched commercially from 1995, with early adoption strongest in the UK, Germany, and the Nordic countries. The original MP2 codec proved spectrally wasteful, so ETSI standardised DAB+ in 2007 with HE-AAC v2 and stronger error protection. Most new deployments and receivers are DAB+, though many multiplexes still carry legacy MP2 services for backward compatibility.
Deployment
DAB/DAB+ is widely deployed across Europe and in parts of Asia-Pacific, and is mandated in some markets for new car radios. Single-frequency networks let every transmitter in a region share one frequency, improving coverage efficiency versus FM. Adoption is uneven globally — North America chose the in-band HD Radio approach instead — so DAB coexists with FM rather than having replaced it.
Decoding it with GopherTrunk
GopherTrunk does not decode DAB. It is a trunked land-mobile scanner (P25, DMR, NXDN, TETRA and similar), and DAB is a broadcast multiplex outside that scope. DAB is, however, a clean real-world example of the coded-OFDM and π/4-DQPSK techniques GopherTrunk readers meet in other digital systems, and general-purpose SDR tools (such as welle.io) can receive and decode a full ensemble from a wideband dongle.
Sources
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Digital audio broadcasting — Wikipedia, for the Eureka-147 origin, Band III COFDM with DQPSK subcarriers, the ensemble/multiplex structure, and the MP2-to-HE-AAC change in DAB+. ↩