Also known as: DMR, Digital Mobile Radio
Digital Mobile Radio (DMR) is an open digital two-way-radio standard from ETSI, widely used in business, commercial, and amateur radio. It places two timeslots (TDMA) in a 12.5 kHz channel using 4FSK modulation and the AMBE+2 vocoder.1
Overview
DMR’s low cost and ETSI openness made it ubiquitous outside public safety. It is defined in three tiers of increasing capability: Tier I (licence-free), Tier II (licensed conventional), and Tier III (trunked with a control channel). Motorola’s MOTOTRBO is the best-known commercial implementation.
Technical characteristics
| Property | Value |
|---|---|
| Access | Two-slot TDMA |
| Channel | 12.5 kHz |
| Modulation | 4FSK, 4800 baud (9600 bps) |
| Vocoder | AMBE+2 |
| Error correction | Golay, Hamming, BPTC, Reed–Solomon (by burst) |
Two-slot TDMA effectively yields 6.25 kHz-equivalent efficiency, letting two calls share one frequency.
History
ETSI published the DMR standard in 2005, with commercial radios following soon after.1 Amateur DMR grew rapidly in the 2010s via networked repeaters and hotspots.
Deployment
DMR dominates commercial/business radio and is popular with amateurs. Trunked deployments use Tier III; most conventional business and ham systems are Tier II.
Decoding it with GopherTrunk
GopherTrunk decodes both DMR timeslots, follows Tier III trunking, and renders AMBE+2 audio. Optional known-key DMR encryption handling is documented separately. See Status.
Sources
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Digital mobile radio — Wikipedia, for the ETSI DMR standard, its two-slot TDMA air interface, the tier structure, and the AMBE+2 vocoder. ↩ ↩2