Digital mobile radio

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Digital mobile radio (DMR) is a digital radio standard for voice and data transmission in non-public radio networks. It was created by the European Telecommunications Standards Institute (ETSI),^[1] and is designed to be low-cost and easy to use. DMR, along with P25 phase II and NXDN are the main competitor technologies in achieving 6.25 kHz equivalent bandwidth using the proprietary AMBE+2 vocoder. DMR and P25 II both use two-slot TDMA in a 12.5 kHz channel, while NXDN uses discrete 6.25 kHz channels using frequency division and TETRA uses a four-slot TDMA in a 25 kHz channel.

DMR was designed with three tiers. DMR tiers I (Unlicensed) and II (Conventional Licensed) were first published in 2005, and DMR III (Trunked version)^[2] was published in 2012, with manufacturers producing products within a few years of each publication.

The primary goal of the standard 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. In practice, given the current limited scope of the DMR standard, many vendors have introduced proprietary features that make their product offerings non-interoperable with other brands.