Fact—there are currently more than 700,000 FCC-licensed ham radio operators in the United States. But it’s also true that only a fraction of these operators are doing something ham radio-related at any given time. Admittedly, I’ll spend several years away from the hobby, and then all of sudden … bam … some new technology or mode will come along and devour my every waking thought.
Five years ago it was D-STAR, a digital voice mode. This time it’s DMR (Digital Mobile Radio), an open digital radio standard. Unlike D-STAR, which was created specifically for ham radio, DMR has been used mostly for commercial and public safety applications. And now it’s being somewhat awkwardly retrofitted to the amateur radio paradigm.
The learning curve for DMR is a bit higher, but the low cost of entry makes it an easy gamble. It’s not that digital voice is difficult. It’s just that a lot of the documentation is hidden away in haphazardly organized “Files” areas spread across unconnected Yahoo Groups. And most of the groups require membership. So if you think you’ll learn about DMR or D-STAR by searching Google for technical information (you know, the way we do things now), you’re in for a frustrating experience.
My venture into DMR circled back through D-STAR and all the development I’d missed over the past several years. It turns out there’s a lot of symbiosis between the two. Mostly in the form of the little low-cost Raspberry Pi computers. My first goal was to marry the two modes in a single Raspberry Pi computer with as many options as possible. You can see the resulting hotspot pictured above.
The hardware consists of a Raspberry Pi 3 B board, a DVMEGA board seated on the GPIO pins, a DV4mini attached directly to USB, and the red DVAP attached to USB by cable.
Also pictured are the ultra-cheap Tytera TYT MD-380 radio for DMR, the Icom ID-51A Plus for D-STAR, and the Yaesu FT2DR for System Fusion.
The software starts with the latest Western D-Star image using Raspbian Jessie Linux, including ircDDBgateway and D-StarRepeater for use with the DVAP and DVMEGA, and the DV4mini application. Then I added MMDVMHost for use with the DVMEGA on DMR, D-STAR, and System Fusion. The SD Card image also functions on the Raspberry Pi 2 B board without any problems.
The DVMEGA board along with the MMDVMHost software is at the heart of this hotspot and can be used for all three modes. Using radio control alone, it connects to the BrandMeister DMR network, the YSF Fusion reflectors, and any D-STAR reflector. The DV4mini will handle D-STAR and DMR, but I’m mostly using it to connect to the DV4mini FCS System Fusion reflectors. It also technically makes this an APCO25 and DPMR hotspot.
Unfortunately, most DMR and D-STAR networks are closed-source systems. So for now, there’s really not much to do but hope for new developments and enjoy some interesting QSOs in the meantime. One exception is the D-STAR X Reflector network. It uses open source software and operates without any real central authority. I’ve set up two XLX reflectors, one for WARN and one for W8IRC. But without an automatic DNS distribution scheme, I doubt the X Reflectors can ever gain full traction as a mainstream competitor to the original DPlus network. I’m on board to try though.
(Originally published on June 21, 2016.)
Thanks to Andrew K4AWC for nudging me in the direction of DMR.