A quick lesson on DMR for beginners, without going into the technical aspects.
DMR (Digital Mobile Radio) is one of the more popular digital voice modes available to Radio Amateurs. It's a commercial radio mode, which has been adapted by Amateurs. One of the reasons for its popularity is because the equipment can be quite inexpensive, compared to the other digital modes. But like anything, there are noticeable quality differences between the cheap radios and the expensive radios. The direction you wish to go is up to you, and it's nice to have options.
DMR is just a mode, like FM, USB, D-STAR, P25, etc. A DMR repeater can be stand-alone (local coverage only), or it can be linked via the Internet to other DMR repeaters, and that's the focus of this post.
For those new to DMR, there are essentially two parts to be aware of. The first is the "talkgroup", and the second is the method of access.
Talkgroups are somewhat similar to radio channels, where each channel has a particular theme, ie. a geographic location or a special interest. For example, the talkgroup "BC-1" is intended for people wishing to communicate in British Columbia, or for people outside of BC who wish to contact somebody within BC.
The method of access can be a repeater or an RF hotspot. To continue our example, the BC-1 talkgroup is available full-time on most repeaters located in British Columbia. So if you're on your local repeater and you're on BC-1, you can communicate with anybody anywhere who is also on BC-1. For areas where there are no linked DMR repeaters, you can use an RF hotspot connected to the Internet, and use your radio to communicate with your hotspot to access BC-1.
In BC, the method of linking the repeaters is primarily done via one of two networks, BC-Trbo or Brandmeister. The talkgroups available on each repeater are controlled by the repeater owner, although Brandmeister provides for some flexibility.
BC-Trbo repeaters have a set list of talkgroups available to use; some are always-on and some are PTT-activated. The repeater owner determines which talkgroups are available, and which of those talkgroups are always-on and which are PTT-activated. Always-on talkgroups are always activated on that repeater. If you switch to an always-on talkgroup, you'll hear the traffic. PTT talkgroups require a key-up to activate. If you switch to a PTT talkgroup, you won't hear anything until you key your microphone. This activates the talkgroup for a set amount of time, ie. 15 minutes, after which it times out. If you're actually conversing, the talkgroup will stay activated until 15 minutes after your last key-up. If you're not conversing, but wish to continue to monitor the talkgroup, you'll have to key up again within 15 minutes.
Brandmeister repeaters have static and dynamic talkgroups. Static talkgroups are always-on, and are determined by the repeater owner. Dynamic talkgroups are determined by the user (you), and are PTT-activated. The advantage of this method is that you now have access to hundreds of talkgroups, which may not be available on BC-Trbo repeaters. The dynamic talkgroups are only active for a set amount of time, ie. 20 minutes, and require a key-up within that time for continued monitoring.
Some talkgroups, like BC-1, are available on both BC-Trbo and Brandmeister networks. So you could be on the Port Moody VHF DMR repeater which uses Brandmeister, and you would be able to communicate with somebody using the Whistler UHF DMR repeater which uses BC-Trbo.
Although some talkgroups are cross-compatible between networks, the talkgroup number might be different. For example, the Canada talkgroup is 302, whether you're on a BC-Trbo repeater or a Brandmeister repeater. BC-1 is 3027 on BC-Trbo, and is 30271 on Brandmeister. BC-2 is 103027 on BC-Trbo, and is 30272 on Brandmeister.
To access a talkgroup, on either network, you would need to pre-program it into your radio. So for example, you might program the BC-1, BC-2, Canada, North America, and World-wide English talkgroups, for your local repeater. If you have more than one local DMR repeater, you might program a duplicate set of talkgroups for another repeater, in case your primary repeater goes down or is otherwise unavailable. If you travel, you could program duplicate sets of talkgroups for DMR repeaters in the areas you're planning on visiting, giving you access to the same talkgroups you always use, no matter which DMR repeater you're using. And if you're travelling to an area without DMR repeater coverage, you could use a hotspot and program a duplicate set of talkgroups for use with your hotspot; as long as you have WiFI or cellular data, you would still be able to access your regular talkgroups.
Programming a DMR radio is a little more involved than programming an analog radio, but it's not too difficult to figure out. I do recommend you take the time to learn how to create a profile for your radio, and not just copy an existing "canned" profile from somebody with the same radio, although that's certainly an option to get on the air quickly.
To get started, you'll need a DMR ID number. This is available at no cost from http://radioid.net/ . Apply for your ID as soon as possible (ie. right now), so that you'll have it when you start to program your radio.
DMR provides a handy and relatively-inexpensive method of communicating with other Radio Amateurs almost anywhere in the world, when HF is not practical or possible. It's just another tool in the box, and who doesn't want a new radio to play with?
Greg