Also known as: dPMR
dPMR (digital private mobile radio) is an ETSI narrowband digital land-mobile standard that carries voice and data in 6.25 kHz FDMA channels using 4FSK modulation and the AMBE+2 vocoder. It is technically very close to NXDN — both are 6.25 kHz FDMA 4FSK systems — and serves the same low-cost, spectrum-efficient niche as an open, multi-vendor alternative to proprietary narrowband radio.1
Overview
dPMR splits into tiers by intended use. Mode 1 is a licence-free, direct-mode (peer-to-peer) tier operating on the shared digital PMR446 channels in Europe — the digital counterpart to analogue walkie-talkies, with no infrastructure. Mode 2 is licensed conventional operation through repeaters, and Mode 3 adds trunking with a control channel, talkgroups, and radio IDs. Across all tiers the physical layer is the same: 6.25 kHz channels, 4FSK at 2400 symbols per second, and AMBE+2 speech coding. That 6.25 kHz channelisation is the headline feature — it packs twice as many talk paths into a band as a 12.5 kHz system, and, like NXDN, it reaches this efficiency with plain FDMA rather than the two-slot TDMA of DMR.
Technical characteristics
| Property | Value |
|---|---|
| Access | FDMA |
| Channel spacing | 6.25 kHz |
| Modulation | 4FSK, 2400 baud |
| Vocoder | AMBE+2 |
| Tiers | Mode 1 (licence-free direct), Mode 2 (licensed conventional), Mode 3 (trunked) |
| Standards | ETSI TS 102 490 (Mode 1), TS 102 658 (Modes 2/3) |
| Voice/data | Digital voice, short data, status, GPS |
History
dPMR was standardised by ETSI during the late-2000s narrowbanding push, published as the TS 102 490 and TS 102 658 series, as an open specification any manufacturer could implement.12 It arrived alongside DMR from the same standards body: DMR targeted the two-slot TDMA route to 6.25 kHz-equivalent efficiency, while dPMR took the simpler FDMA route. Its near-identical relationship to Japan’s NXDN reflects convergent engineering — both settled on 6.25 kHz 4FSK with AMBE+2 as the natural low-cost narrowband digital design of the era.
Deployment
dPMR is used mainly in European and international business radio — retail, security, hospitality, transport, and light industry — where its licence-free Mode 1 makes it an easy analogue-to-digital upgrade for small users. It is less common in North America than DMR or NXDN, reflecting regional vendor support and regulatory history. Networked and trunked dPMR systems exist but are far less widespread than DMR trunking.
Decoding it with GopherTrunk
Because dPMR shares NXDN’s narrowband 4FSK physical layer, GopherTrunk decodes it through much the same receiver chain — symbol timing, discriminator, and frame sync — differing mainly in frame layout and higher-layer signalling. Clear voice can be recovered where an AMBE+2 vocoder is available; keyed encryption is out of scope for GopherTrunk’s receiver-only design. See the Status page for the current state of dPMR support.
Sources
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dPMR — Wikipedia, for the ETSI 6.25 kHz FDMA 4FSK standard, its Mode 1/2/3 tiers, and its relationship to NXDN. ↩ ↩2
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ETSI — Digital Mobile Radio — ETSI, the standards body, for the dPMR (TS 102 490 / TS 102 658) and DMR narrowband digital land-mobile specifications. ↩