The more I fiddle with DMR, the more I think it’s an evolutionary dead end in Amateur Radio.
There is a lot of smoke and heat regarding systems like DMR, and D-Star, and even IRLP and EchoLink that allow amateurs to connect to far-off lands via repeaters that are linked via the Internet. I’m not going to sit here and make the stupid argument that linked repeaters “aren’t radio” because of the TCP/IP link that does all the heavy lifting so you can talk to some other ham in South Waziristan via your local 70cm repeater.*
But I am concerned more and more about the ability to deliver on the DMR promise of local, regional, and worldwide communication across TDMA repeaters that have two time slots, or “channels”. Even with the local, regional, and statewide talkgroups on TS2, and the others on TS1, there’s still going to be conflict when two locals are trying to have a QSO and someone on statewide or Midwest tries to have a different QSO. (Yes, I understand that there are lockouts and timeouts that prevent you from stepping on the other guy.) The only real answer I see to that is to have multiple repeaters in a given area and break up the talkgroups among them so that each time slot on each repeater has less of a load. But that defeats the purpose, I think. Another solution would be to split the bandwidth even further and go to four time slots of (effectively) 3.125MHz bandwidth each. The question is whether or not you could reliably and intelligibly transmit digital audio in 3.125MHz. (To clarify, DMR transmits TDMA 12.5MHz, but delivers the two time slots by interleaving the two signals to produce an “effective” 6.25MHz bandwidth per time slot.) And another solution, I suppose, would be to introduce trunking…which I don’t think anyone really wants to do, because it is horrendously expensive.
And let’s face it. If you really want to talk through the Internet with someone in South Waziristan, chances are it would be a lot simpler to fire up Skype.
The other concern that I have about DMR is the absolutely shitful programming software that is available for these really sophisticated radios. I’m pretty certain that the software is shit because DMR started life as a commercial radio solution (MOTOTRBO) and, as someone who had to purchase a couple of Motorola handhelds for a building management association I once worked with, I found that such radios sold in a commercial venue are damned expensive. On top of that, you don’t get programming software, because the vendor who sells them to you programs them for you. At a cost. And if you add channels, they reprogram them for you. At a cost. So even though the TRBO-type DMR radios have been around for some time, there’s been no particular reason for the manufacturers to come up with inexpensive, user-friendly programming software for them. And why would they do that? Buying a license for Motorola programming software appears to be a five-figure expense, from what I’ve seen on the ‘Net.
So Hytera/Tytera/TYT, who are the ones selling the comparatively-inexpensive DMR handhelds right now, but who also have a thriving commercial business where I imagine they also make big bucks selling programming software to vendors, have produced a piece of crap for end-user amateurs that requires a lot of work and sweat and blood to enter all the information you need just to program your shiny new MD-380 handheld. Among the shortcomings of this piece of crap are 1) you can’t cut and paste from one codeplug to another, and 2) you can’t re-arrange things like group or contact lists easily (or at all, really). In addition, the documentation sucks and the ancient MDI Windows interface is an embarrassment, and makes the thing really hard to use. Why couldn’t they have used a tabbed window?
Someone needs to get one of these radios to RT Systems and beg them to build a programmer for them.
Another problem: The fragmented nature of the DMR “network”. In Indiana, we have two competing networks, Hoosier DMR and Crossroads DMR. They don’t link and the operators apparently have no interest in making them link. But that’s the usual problem you get in any arena when personalities get involved. In the real world, if this were a commercial endeavor, there would be a national oversight body that would smooth over the personalities and make the system work. But this is ham radio, so forget about anything like that.
Anyway, for me, the warm fuzzy glow of DMR has sort of worn off. I’m seriously considering selling my MD-380 and buying a Yaesu FT-2DR. At least I could get a decent programmer for it, and still use it in analog mode (and on 2M).
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* I’m only leaving out Yaesu because System Fusion, while it does support Internet linkage via the WIRES and WIRES2 interfaces, seems to be aimed more at the concept of letting folks with analog and digital radios interact on a more local basis. So far I don’t see any real way to do that with DMR and D-Star.