The Road Back to Radio – Digital Voice

DV Hotspot

Hotspot for DMR, D-STAR, Fusion, and P25

There are more than 700,000 FCC-licensed ham radio operators in the United States, but only a small fraction are actively engaged in the hobby at any given time. Although I’m often one of those inactive people, every few years I get interested in some new area of the hobby.

Five years ago it was D-STAR, a digital voice mode. This time it’s DMR (Digital Mobile Radio), another digital voice mode mostly used for commercial and public safety applications that’s being somewhat awkwardly retrofitted to the amateur radio paradigm. While the learning curve with DMR is a bit higher, the low cost of entry makes it an easy gamble. It’s not that digital voice is necessarily difficult, but a good portion of the documentation and know-how for both modes is hidden away in haphazardly organized “Files” areas spread across a lot of unconnected Yahoo Groups, most of which require membership. Anybody approaching DMR or D-STAR with simple and reliable methods like scouring Google for technical information is in for a frustrating experience.

Roadblocks aside, my venture into DMR circled back through D-STAR and all the development I’d missed over the past several years. There’s a lot of symbiosis between DMR and D-STAR activity, 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 box with as many options as possible. The result is the 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.

The software starts with the latest Western D-Star image using Raspbian Jessie Linux, including ircDDBgateway and D-StarRepeater for use with the D-STAR DVAP, and the DV4mini and DV4MF2 software for the DV4mini. I added MMDVMHost for use with the DVMEGA on DMR. The SD Card image also works fine on the Raspberry Pi 2 B board.

Also pictured are the ultra-cheap Tytera TYT MD-380 radio for DMR and the not-so-cheap Icom IC-92AD radio for D-STAR.

The DVMEGA can be used for D-STAR instead of the DVAP, but it’s being dedicated to DMR so that both modes can be used at the same time. The DV4mini doesn’t get much use in this setup, but it covers a few things that can’t be done with the other hardware. For one, it makes this a System Fusion C4FM hotspot, yet another digital voice mode for amateur radio, created by Yaesu. I’m leery of spending the kind of money Yaesu is asking for a Fusion rig until somebody can convince me that activity will actually grow there, so it’s just DMR and D-STAR for now.

Since most DMR and D-STAR networks are closed-source systems, there’s really not much else to do at the moment other than hope for new developments and enjoy some interesting QSOs with other hams in the meantime. The one possible exception to this is the D-STAR X Reflector network that uses open source software and operates without any real central authority. I’ve set up an XLX Reflector and have another dxrfd-based X Reflector in the works, but without an automatic DNS distribution scheme, I’m doubtful that the X Reflectors can ever gain full traction as a mainstream competitor to the original DPlus network. I’m on board to try though.

Edit 2016-08-02: I just bought a Yaesu FT2DR System Fusion rig, so the DV4mini is now getting lots of use again in the hotspot.

(Thanks to Andrew K4AWC for nudging me in the direction of DMR.)