What is DMR
Digital mobile radio (DMR) is an open digital radio standard for PMR users specified in the European Telecommunications Standards Institude (ETSI) and used in products sold in all regions of the world.
The DMR standard operates within the existing 12.5 kHz 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 into 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. The specification covers the RF frequency range 30 MHz to 1 GHz and uses 4 level FSK modulation.
DMR Tier I
DMR Tier I products are for license-free use in the European PMR 446MHz band. This part of the standard provides for consumer applications and low-power commercial applications, using a maximum of 0.5 watt RF power. There have been no commercial launches of DMR Tier 1 products to date.
DMR Tier II
DMR Tier II covers licensed conventional radio systems, mobiles and hand portables operating in PMR VHF/UHF frequency bands. 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. A number of manufacturers have DMR Tier II compliant products on the market. TIER II is the standard used by Ham Radio.
DMR Tier III
DMR Tier III covers trunking operation in the VHF/UHF frequency bands The Tier III standard specifies two slot TDMA in 12.5 kHz channels. Tier III supports voice and short messaging handling 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. Tier III compliant products were launched in 2012.
Hytera introduction to DMR technology.