Introduction to DMR
Digital Mobile Radio (DMR) is an open digital radio standard for Professional Mobile Radio (PMR) users by the European Telecommunications Standards Institute (ETSI) Standards TS 102 361 parts 1 to 4 and used in products sold in all regions of the world. The applicable compliance standards are EN 300 113 and EN 300 390.
Products built to the DMR standard also comply with the FCC mandates in the United States for the use and certification of 12.5 kHz and 6.25 kHz narrowband technology for systems covered by Part 90 regulations.
The DMR standard operates within the existing channel spacing used in land mobile frequency bands globally. Its primary goal is to specify a digital system with low complexity, low cost and interoperability across brands, so radio communications purchasers are not locked in to a proprietary solution. DMR provides voice, data and other supplementary services. DMR is a two-slot, Time Division Multiple Access (TDMA) system offering voice, data and a range of other features and applications.
In 2005, a Memorandum of Understanding (MOU) was formed with potential DMR suppliers including Tait, Fylde Micro, Selex, Motorola, Vertex Standard, Kenwood and Icom to establish common standards and interoperability. While the DMR standard does not specify the vocoder, MOU members agreed to use the half rate DVSI Advanced Multi-Band Excitation (AMBE) vocoder to ensure interoperability. In 2009 the members of the MOU set up the DMR Association to work on interoperability between vendors equipment and to provide information about the DMR standard.
DMR Tier I, II and III
DMR Tier I
DMR Tier I products are for license-free use in the 446 MHz band in the European Union.
This part of the standard provides for consumer applications and low-power commercial applications, using a maximum of 0.5 watt RF power. With a limited number of channels and no use of repeaters, no use of telephone interconnects, fixed/integrated antennas, and a talk timer of 180 seconds, Tier I DMR devices are best suited for personal use, recreation, small retail and other settings that do not require wide area coverage or advanced features.
In North and South America the 446.0 - 446.2 MHz band is part of the amateur radio 70 cm band and requires an amateur radio license.
DMR Tier II
DMR Tier II covers licensed conventional radio systems, mobiles and hand portables operating in PMR frequency bands from 66-960MHz.
The ETSI DMR Tier II standard is targeted at those users who need spectral efficiency, advanced voice features and integrated IP data services in licensed bands for high-power communications. ETSI DMR Tier II specifies two slot TDMA in 12.5 kHz channels.
DMR Tier II is based on the following ETSI standards.
DMR Tier III
DMR Tier III covers trunking operation in frequency bands 66-960MHz. The Tier III standard specifies two slot TDMA in 12.5kHz channels. Tier III supports voice and short messaging handling similar to MPT 1327 with built-in 128 character status messaging and short messaging with up to 288 bits of data in a variety of formats. It also supports packet data service in a variety of formats, including support for IPv4 and IPv6.
You can use the following to decode a DMR Transmission.
- GRE \ Radio Shack \ Whistler
- Using modified Whistler firmware. See the Whistler Official Upgrade (WOU) article
- Firmware CPU 3.8 & DSP 2.9 or better use.
- Directly out-of-the-box Whistler announcement.
See their respective wiki articles for additional details:
- Firmware 1.07.06 or better, updates via the USB Mini-B port.
- Firmware 1.11.15 or better, for both models via the microSD, or the USB Mini-B port.
Using a computer it's possible to use DMRDecode to view and decode system and channel data with a receiver - either the Discriminator output of a scanner OR with a variety of Software Defined Radios (SDRs) devices. Using DSD or DSDPlus to further decode data and voice
- Radios with no trunking support
- Radios not yet released