DMR Radio

[pkveazey]

Well, I'm starting to get a better handle on how this digital VHF/UHF stuff works. When I think about all the Talk Groups, they seem to be like web site chat rooms. They work pretty much the same way. They are both on the internet and they have specific numbered names. Once you set up to listen to a particular Talk Group its like watching what people post on a chat room. Our local repeater is set up to use LOCAL, STATEWIDE, MID-ATLANTIC, SOUTHEAST, USA, and WORLWIDE. It also has a couple of others. As long as the internet is up and running, you can talk all over the place. If the internet goes down, you can throw that DMR radio in a drawer and forget about it. I'm getting used to the Robbie the Robot voice thing. Some of the DMR radios have a very robotic voice quality and some of them have hardly any at all. The price of the radio doesn't seem to enter into the equation. Some of the newer cheap radios sound natural enough that I can even recognize some people's voice. Some radios are so robotic that I have no idea who it is until they give their call sign. I'm told that Yaesu's Fusion radios are easier to operate and don't sound very robotic at all. Hmmmmmmm….. Well, that's all well and good but most of the newbies are not using Fusion or Icom's DSTAR. If you are going to get into Digital VHF/UHF, you're going to have a bigger audience with DMR. I've also noticed that most of the DMR repeaters are using UHF and there are a few VHF DMR repeaters here and there. I may try to add one or two VHF DMR repeaters into my memory bank.

[Jackalope]

   PK, you are correct regarding Yaesu Fusion, it's extremely easy to use, and of all the digital voice modes, it has the best fidelity, such as it is.  In the event of a nationwide internet outage, DMR radios could still operate in conventional FM mode, so they would still have some functionality.  DMR radios can also be used in digital simplex mode, which offer some minimal privacy.  DMR radios tend to be less flexible when they're being programmed, and it's not easy to program the radio while on the fly.  DMR radios use what are known as code plugs, which contain all the frequency and data information needed to make the radio operate properly.   The code plug nomenclature comes from Motorola radios, which have always had complicated programming.  Regional codeplugs are becoming more popular, so that should improve the usability of DMR radios.

 Dstar is a cool digital mode too, and it offers lots of versatility.  Though Dstar programming isn't quite as difficult as DMR, it still takes time and a good understanding of the radio in use.  As mentioned earlier, System Fusion is very easy to program, a user can be using the radio within a minute or so.   Digital modes convert audio from analog to digital, so your voice audio becomes essentially data.  So digital modes, in addition to voice transmissions, permits the user to transceive other types of data, i.e. text and images.

    As PK pointed out, without an internet connection, digital modes lose a lot of their versatility.  APRS is another mode that uses conventional FM or DMR, but it also permits the transmission of data.  At this point in time, the various digital mode radios cannot directly communicate with one another, while using their digital capabilities, but there is a way around this limitation, which I'll discuss in a bit.  All the various digital modes have their pros and cons, and the modes seem to be region specific.  For instance, there's lots of DMR activity in the northeastern U.S., while Dstar seems to be a southern US. mode, but there are lots of exceptions.  In my immediate area, Yaesu Fusion is the mode of choice.  Pricing is also a factor in the popularity of the different modes, and DMR is surging due to low priced radios produced in China.

   A hotspot allows radio users to use the internet for radio connections.  A hotspot takes a local digital radio signal and transmits through the internet.  What's neat about the newer hotspots is that they are mode transparent.  So a Dstar radio user can use a DMR talk group, or a DMR radio user can access a Dtar reflector or repeater.  So the type of digital mode in use, is less important when using a hotspot.

    I imagine that in the near future we'll see a radio that will be digital mode transparent.  If hotspots can be mode transparent, then radios should soon follow.  Conventional FM still has the best audio, but it takes a lot of bandwidth.  Digital radios are supposedly the solution, since they allow more voice/data channels to fit within a specific bandwidth.  The digital modes were originally intended for urban areas, where agencies/groups were running out of available empty frequencies.  In the American public service portion of the radio spectrum, all users were forced to narrowband their signals, and digital modes were part of the solution. 

    There's lots of new developments in the digital modes, and prices are finally starting to drop.  It's a great time to be active in amateur radio!