This is intended to be a handy startup guide to the topic of DMR Radios and the linux environment, both from the end user, and infrastructure user point of view. It will likely become outdated if too much time is spent on technical details, so an overview that teaches concepts is what this really is.
DMR radios that support AES256 are starting to become available at price levels that more people are willing to invest in the technology. The most notable example at this point is the Baofeng DM32, which while styled like one of the Motorola APX radios, takes something of a left turn, and rather than using the P25 protocol, has opted for the more common and lower barrier of entry DMR platform.
Some quick discussion of what DMR is, DMR aka Digital Mobile Radio is a European (ETSI) radio standard that uses the TDMA (allowing for two timeslots), supports digital trunking, talk groups, encryption and a number of other modern radio features.
For many, a major attraction of digital radio, is the ability to link radio networks over the internet, systems like DMR MARC, and Brandmeister have globally linked DMR based networks, however a major feature of these systems is they can translate between different flavors of digital radio (P25, System Fusion, D-Star, DMR) and allow them to all talk together in a somewhat agnostic fashion. Both of these systems can use MMDVM hotspots, often running Pi-Star which can bridge a local area network to a DMR network using a MMDVM “Hat” that connects to some flavor of Raspberry-pi single board computer.
Over the last 7-10 years, as more interest has developed, Open-source reflectors (systems like Brandmeister, TGIF, etc are reflectors) using XLXd, in fact many of the major networks have moved over the XLXd.
Many regions don’t have any kind of native Digital repeaters, which would allow an onramp to the global Digital networks, hotspots are a handy way to bridge the gap until more of these systems come online.