Also known as: DMR Tier II, DMR Tier 2
DMR Tier II is the licensed, conventional tier of the DMR standard. It is non-trunked — each repeater pair uses fixed frequencies — but carries two voice timeslots per 12.5 kHz channel via TDMA.1
Overview
Tier II is the workhorse of commercial DMR and the basis of amateur DMR repeaters. Because it is conventional, you tune directly to a known frequency rather than following a control channel; the two timeslots still allow two simultaneous conversations.
Technical characteristics
| Property | Value |
|---|---|
| Access | Two-slot TDMA |
| Channel | 12.5 kHz |
| Modulation | 4FSK, 9600 bps |
| Vocoder | AMBE+2 |
History
Tier II was the first widely commercialised DMR tier, popularised by Motorola’s MOTOTRBO line from the late 2000s.1
Deployment
Extremely common in business, utility, and amateur radio. Amateur networks bridge Tier II repeaters and hotspots over the internet.
Decoding it with GopherTrunk
GopherTrunk decodes both timeslots of a Tier II channel and renders AMBE+2 audio.
Color Code, time slot, and talkgroup are read off the air per call — you only
configure each repeater’s frequency. A single dongle channelizes a cluster of
repeaters at once; to cover many repeaters spread across a wide band, add one
role: wideband dongle per ~2 MHz cluster, all pointed at the same system. The
dmr-tier2-multi-repeater
sample is a worked “a bunch of repeaters, different CCs and slots” config; for a
single carrier see
dmr-simplex.
For trunked DMR, see Tier III. See Status.
Sources
-
Digital mobile radio — Wikipedia, for the ETSI DMR tiers, including the licensed conventional Tier II and its two-slot TDMA. ↩ ↩2