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.12
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 on that one carrier. Each slot is independently addressed by color code, talkgroup, and source radio ID, all embedded in the burst so a receiver reads them off the air. A single repeater can therefore host, say, a dispatch talkgroup on slot 1 and a networked amateur talkgroup on slot 2 at the same time.
Technical characteristics
| Property | Value |
|---|---|
| Access | Two-slot TDMA |
| Channel | 12.5 kHz |
| Modulation | 4FSK, 9600 bps |
| Vocoder | AMBE+2 |
| Squelch / identity | color code, slot, talkgroup, source ID |
History
Tier II was the first widely commercialised DMR tier, popularised by Motorola’s MOTOTRBO line from the late 2000s and quickly matched by other DMR Association members.12 Its two-slot efficiency and open standard let it displace both analog repeaters and older proprietary digital systems.
Deployment
Extremely common in business, utility, security, and amateur radio. Amateur networks (such as the large worldwide DMR talkgroup systems) bridge Tier II repeaters and personal hotspots over the internet, so a low-power handheld can reach global talkgroups through a nearby repeater.
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
-
DMR Association — the DMR manufacturer association, for the TS 102 361 basis and Tier II conventional interoperability. ↩ ↩2