An Introduction to DMR
DMR is Digital Mobile Radio
An open standard created as defined by the European Telecommunications Standards Institute or ETSI
What you need to know
Like NXDN, where there is the NXDN Forum comprising of 30 members such as radio and accessory manufacturers, DMR has a DMR Association
The DMR Association was established in 2005 and is made up of 40 members including JVC Kenwood, Icom, Motorola, Tait, and Hytera to name a few.
According to the DMR Association, the key benefits of DMR are:
- Doubling the capacity of existing licenses
- Backwards spectrum compatibility with legacy systems
- Efficient use of infrastructure equipment
- Longer battery life
- Ease of use and creation of data apps
- System flexibility through simultaneous use of TDMA Channels
- Advanced controlled features
- Superior audio performance
- Security of supply through a fully open standard
While the DMR protocol does not specify what vocoder to use, the Association voted to use the DVSI AMBE vocoder to ensure interoperability. And just like P25 and NXDN, manufacturers can add their own equipment into the DMR setup making the end user reliant or locked into a manufacturer’s equipment. Thus removing the interoperability part of DMR.
Like P25 and NXDN, it uses the proprietary AMBE +2 vocoder by DVSI
DMR uses color codes in the same way that analog signal uses PL or DPL, P25 uses NAC, and NXDN uses RAN codes.
Like P25 and NXDN, DMR is a pure digital type of transmission. There is no analog on a DMR signal
And like P25 and NXDN, DMR supports Encryption
Like P25 Phase 2, DMR uses TDMA or Time Division Multiple Access
DMR uses a two time slot TDMA carrier to split the conversation into two parts on the same frequency using 12.5kHz bandwidth
DMR is broken down into 3 tiers.
According to the DMR Associations Standards webpage:
DMR Tier I
License free use in the European PRM446 band
Simplex use only – no repeaters
Maximum of half a watt
No repeaters, or telephone interconnects
Must use fixed antennas
Suited for Personal use, recreation, small retail that do not require a large coverage area
The European PMR446 band operates on 446MHz and it is very similar to MURS or FRS here in the US.
DMR Tier II
Licensed Conventional Radio
Covers 66Mhz – 960Mhz in the EU Spectrum
Targeted for those who need spectrum efficiency
Offers advanced voice features
For High power communications
ETSI Specs require TDMA 12.5khz bandwidth
DMR Tier III – we will talk about this more next week.
Licensed Trunking Radio
Covers 66Mhz – 960Mhz in the EU Spectrum
Uses two slot TDMA
Offers advanced voice features
Offers Short messaging limited to 128 characters
Also 288bits for data in various formats
So what information do we need when programming DMR conventional into our scanners?
A radio capable of picking up DMR
We need the receive frequency.
Optional Color Code and TS
And the Talk Group
You will also need to program in the LCN (Logical Channel Number) into the scanner for each traffic channel. Usually the LCN’s are paired for each TDMA channel. Ex, Ch 1 & 2 are the same freq, Ch 3 & 4, so on and so forth.
Scanners that support DMR:
If you pay for the Whistler Offical Upgrade:
GRE PSR-800, Radio Shack PRO-668, and PRO-18
Via a Free Whister Upgrade:
WS1080, WS1088, WS1095, and WS1098
Out of the Box:
Whistler TRX-1 and TRX-2
With paid upgrades:
Uniden BCD436HP, BCD536HP, SDS100, BCD325P2, BCD996P2
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Links and Sources from this session:
Wikipedia https://en.wikipedia.org/wiki/Digital_mobile_radio
ETSI TS 102 361-1 v 2.4.1 https://www.etsi.org/deliver/etsi_ts/102300_102399/10236101/02.04.01_60/ts_10236101v020401p.pdf
DMR Association https://www.dmrassociation.org/
Radio Reference Wiki: https://wiki.radioreference.com/index.php/MOTOTRBO
Bonus Material:
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Download our new e-guide, “5 Thinks You Need to Know Before Buying Your First Scanner”. This free PDF is about 30 pages long and has 5 things you should look for, plus a few extra bonus items to make sure you make an educated purchase.
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