Field Guide · protocol

Also known as: DMR Tier I, DMR Tier 1

DMR Tier I is the licence-free tier of the DMR standard, defined by ETSI for low-power, short-range consumer and light commercial use without an individual user licence.12

fixed low-power channel licence-free, no trunking
DMR Tier I uses fixed, low-power licence-free channels with no system planning or trunking.

Overview

Tier I targets the same role as licence-free analog radios (PMR446-style walkie-talkies) but in digital form. It uses fixed low power and a small set of designated channels, so no frequency coordination, system planning, or trunking is involved. Equipment is simple and inexpensive: a Tier I handheld typically uses a single timeslot on a fixed channel rather than exploiting the full two-slot TDMA structure of the higher tiers, though it uses the same 4FSK modulation and AMBE+2 vocoder.

Technical characteristics

Property Value
Licensing Licence-free, limited power
Access Conventional (TDMA-capable hardware)
Channel 12.5 kHz
Modulation 4FSK
Vocoder AMBE+2
Squelch color code

Because there is no control channel and no per-user licence, Tier I is the simplest thing DMR can be: a fixed frequency, a color code to keep neighbouring users from hearing each other, and a talkgroup. This makes it functionally a digital replacement for consumer FRS/PMR446 radios.

History

Tier I was specified alongside the other tiers in ETSI’s DMR documents (TS 102 361) to cover the unlicensed consumer segment, complementing the licensed conventional Tier II and trunked Tier III.12

Deployment

Found in inexpensive consumer handhelds in regions that allocate licence-free DMR channels; it is less common than Tier II in North America, where most DMR activity is licensed commercial or amateur. Where allowed, it appeals to businesses wanting cheap, no-paperwork digital radios.

Decoding it with GopherTrunk

Tier I traffic is just conventional DMR on a fixed channel, so it decodes exactly like any Tier II conventional channel once tuned: GopherTrunk reads the color code and slot and renders the AMBE+2 audio. There is no trunking control to follow. See Status.

Sources

  1. Digital mobile radio — Wikipedia, for the ETSI DMR tier structure, including the licence-free Tier I. ↩ ↩2

  2. DMR Association — the DMR manufacturer association, for the TS 102 361 tier definitions and the licence-free Tier I role. ↩ ↩2

See also

Learn it step by step

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