*Some Thoughts On DMR Radio*
29 September 2019
The use of VHF/UHF amateur digital radios for preparedness purposes has been questioned because of the perceived dependence on the Internet. This article will attempt to address that issue as it relates to DMR systems. But first, Digital Mobile Radio (DMR) is not a generic term for digital radio systems but is a specific commercial radio specification that originated in Europe. So DMR, D-Star and Fusion are completely different systems. The three systems are not directly compatible and radios from one system will not talk to the other systems.
DMR probably has the largest diversity of equipment, all of it mostly compatible with Motorola's MotoTrbo systems; there are numerous manufacturers ranging from relatively expensive Motorola radios to inexpensive imports. D-Star was promoted by the Japanese government; Icom is most associated with it but there are a few other manufacturers. System Fusion is proprietary to Yaesu and requires their equipment.
One of the confusing things about DMR is it was designed as a commercial radio system, not amateur radio, so nothing about it uses our familiar ham terminology. But it is completely compatible with ham use, it just requires accepting the oddities of the system.
For everyday use, much of the ham DMR world lives on the Brandmeister network (link below), which is a group of repeaters and servers located around the world which are linked via the Internet. So you can carry on a conversation with people all over the world. The types of conversations vary, and there is a wide range of "Talkgroups" dedicated to specific topics. Keep in mind, despite the Internet linking in the middle, this is real Amateur radio on both ends, so amateur rules apply. That may limit some political or controversial topics.
It's important not to be mislead by the Internet aspect - first of all, the radios (HT or mobile) are real radios that work just fine without the Internet connection. They can be used simplex (radio to radio) or through a DMR repeater, just like using an analog FM radio. Plus, most models aimed at the ham radio market are dual use DMR and analog FM so they can also be used simplex with conventional FM radios or via your standard FM repeater. So if you are within range of a DMR repeater or within simplex range of another DMR radio you can do real DMR without Internet - no computer required. The same is true for making analog FM contacts using DMR radios which support FM.
If you want to take advantage of Internet linking to distant repeaters (and the Internet is available) but you are not within range of a linked DMR repeater you can use a personal Hotspot to link to a DMR network over the Internet. Typically a Hotspot is set up as a very low power UHF "mini-repeater" hooked to the Internet that you connect to via a UHF HT set to low power. It is frequently used by people who do not have access to a local DMR repeater, or who use the Brandmeister network enough to use a Hotspot to avoid tying up their local repeater. Like any other repeater access, it can be used for one-on-one QSOs or group round-table conversations. Hotspots can also be used as a bridge to connect DMR radios to networks supporting other digital systems.
As an example of the utility of a linked system, there is a regional DMR group that has a number of linked DMR repeaters. They have generously configured Internet accessible servers that allow Hotspots access to their network. A no-cost membership in their club provides Internet access, but it is limited to people in the region to reduce congestion. One of their Talkgroups is the I-5 Corridor talkgroup, which attempts to provide complete I-5 coverage from the Canadian border south to California. This, combined with a mobile DMR radio, could prove very useful for someone traveling the I-5 corridor who wants to "call home" occasionally. If Internet linking is not available the DMR repeater coverage at any given location might still be available for local use in highway emergencies.
At the end of the day, they are still radios and if the Internet goes away you can talk to other DMR users in your local area over simplex just as easily as you can with a Baofeng. Better, actually, because blister pack radios, conventional FM rigs and low cost scanners won't receive/scan DMR. Many DMR radio models will also communicate with conventional analog FM rigs giving you the best of both worlds. There is a learning curve involved, but once the terminology and concepts are learned DMR becomes another tool in the toolbox.
There's a lot more but there are plenty of resources on the Internet that will help demystify DMR. Here are a few quick references:
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