Digital mobile radio

Digital Mobile Radio often shortened to DMR, is an ETSI Open Standard for Digital Handheld Transceivers, used by Amateur and Commerical users alike, DMR is one of the most popular DV (digital voice modes) used by amateurs, despite more amateur orientated modes appearing on the scene (C4FM, etc)

DMR uses Two Slot TDMA and the AMBE vocoder, the transmitted signals are roughly 12.5 kHz wide allowing them to fit into existing NBFM allocations.

DMR has three Tiers, I, II and III.

• Tier I systems are DMR radios which operate on the European licence-by-rule PMR446 band, similar to dPMR.

• Tier II systems are conventional or simplex, where radios on licenced frequencies communicate directly with each other, this is the mode that amateurs use.

• Tier III systems are not used by amateurs, and are trunking systems, meaning the radios communicate via a network similar to a mobile phone network.

Tier II DMR saw an explosion in use by amateurs in the 2010s, leading to the FCC to offically approve the use of the mode by amateurs in 2014. Despite being Tier II, Tier III-like functionality is often provided by internet connected repeaters or Hotspots operating on a network such as BrandMeister.