M1FJU

Quite a few radio amateurs, it would appear from my on-air and face-to-face encounters with some them. In this post, I address what appear to me to be the two main obstacles to getting involved for those who are reluctant to do so. First of all, though, what is DMR? DMR stands for “Digital Mobile Radio”. It is an ETSI standard for digital voice communication, promulgated originally by Motorola, for use with mobile and/or handheld radios in the business environment. See here for more information. It is now widely used, also, by amateurs, mainly on the 70cm band (UHF) but also on the 2m band (VHF). Now for those two obstacles:-

Ideological obstacle: “DMR relies too much on the Internet. It’s not real radio.”

It is a myth that DMR relies on the Internet. I, too, would consider such reliance a bit of a downer, if it were true! In fact, people can communicate directly with each other using DMR equipment over the air just as they can with analogue radios. Similarly, they can talk to each other, using DMR, through a single in-range repeater, just as with analogue. The chief advantage of using DMR (or any other digital voice mode) in this way is that the background noise typical of analogue voice reception is completely filtered out during the decoding of the digital audio signal and its conversion back to analogue. The chief drawback is the greater cost of DMR radios (which typically do analogue, too) compared with that of analogue-only ones.

On the other hand, there are people who do want to talk reliably to the world, or parts of it, beyond the range of their local repeater. To make this possible, the repeater must be linked into some sort of network. The simplest (and usually the cheapest) way of doing this is to make use of the Internet. This applies equally to analogue (think Echolink, etc.) and digital modes. Digital modes, though, have more built-in features, flexibility and versatility for use in this way.

In practice, most DMR repeaters, if not all, have links to and through the Internet but neither they nor you need to use those links for local communications through a single repeater.

If you want to take advantage of these Internet links, you have that choice. You must still use an actual DMR radio (not a direct Internet connection) to transmit and receive, so part, at least, of your communication path is always over the air. But what if you can’t reach a DMR repeater from your location? Well, you can buy or build your own “hotspot” which acts a private gateway between your radio and the Internet, typically via your home router..

Practical obstacle: “DMR is overly complex and it is difficult to set up a DMR radio for use.”

I can’t argue with the first part of this statement. DMR is, indeed, complex when compared with amateur-specific digital modes like System Fusion (Yaesu) and D-Star (Icom and Kenwood). This is because DMR was designed originally for business use and has a plethora of concepts and features that it was considered businesses might need or want. Here is a list:-

Channels, Slots, Colour-Codes, Zones, Scan Lists, Monitor, Roaming, Radio ID, Talk Groups, Receive Group Lists, Private Contacts, SMS, GPS Location, Encryption, Call Log, Recording, Emergency Facilities, Digital (CSV) Contact List.

The good news is that you need to understand and set up, on your radio, only the items I have underlined, in order to get started on the air with DMR. There is much information – too much, perhaps – already on the Web about DMR, and more to follow on this blog but I recommend that those starting out should concentrate only on these underlined items, initially, to avoid information overload! Encryption is forbidden on the amateur bands, so I have stricken through that item. The other items are optional. Some are more useful than others, for radio amateurs, and some are applicable to simplex mode only, as repeater operators typically have restrictions on the kinds of traffic they can deal with.

A feature of setting up a DMR radio is the installation of a so-called, badly-named “code plug”, using a PC and a suitable cable. This is not such a horrible process as it sounds to many newcomers to DMR. You do not have to write actual computer code to “program” your radio, of course. It’s more like using an elaborate version of Chirp to fill in data tables and upload them.

If you choose to get the most amateur-friendly brand of radio to launch your DMR experience, you can even get on the air (analogue and/or DMR) via its menu system, without even going near a PC! You won’t want to use this approach too often, though; you’ll eventually succumb to the code-plug approach because it’s much less tedious.

Later posts will cover the practicalities of DMR in more detail.