How to Set Up Amateur Radio Digital Voice Hotspot With Pi-Star and mmdvm

Want to learn how to set up an amateur radio digital voice hotspot? Check out this post to learn how using mmdvm and Pi-Star setup —DSTAR, DMR, and other modes.

After setting up an SD Card with the Pi-Star image, booting it up, and then hitting http://pi-star.local in a browser on my laptop, I used the default user ID “pi-star,” password “raspberry,” to get to the dashboard page and set up the modes that you want to operate. For this part of the setup, I followed many of the existing guides and videos online, some of which I collected here, but the best guide I found was this one by KE0FHS.

mmdvm board

The OLED display only appears to be active when connected to Wi-Fi and is not active when on a wired connection. I set up mine on a wired connection first and was fiddling with the different display settings. When I had set up the Wi-Fi and rebooted the board with Wi-Fi, the screen started working. This is not totally obvious, but I think I read comments elsewhere that this is the expected behavior.

mmdvm board working on a Pi3, before moving to Pi Zero W

Some mmdvm boards are configured with a Tx-Rx offset (from photos online, usually indicated with a sticker on the board), but apparently, mine had zero offsets (it also didn’t have a sticker). From watching the board transmit using my SDRPlay when it was receiving D-STAR traffic from the reflector, I set it to transmit local, spot-on frequency. Pi-Star showed it on 438.800Mhz, and it was right on the money.

Setting up a DV/DR repeater memory on my Icom 880 radio with the correct settings was absolutely key to getting everything working. It’s been a few years since I’ve used D-STAR, and it’s a good job I kept some notes here — it would have taken hours to work this out again. Some of the key settings to get this working were:

  • The hotspot repeater name of ‘KK6DCT B’ needed to be set EXACTLY in the repeater name setting for the DV memory setting on the radio, otherwise keying up the radio wouldn’t even appear on the mmdvm status page. It seems that the transmissions are completely ignored by the hotspot (presumably because it’s not hearing traffic matching its own hotspot name, so this is probably intentional).
  • Using the GRP UR setting on the 880 to send BOTH RPT1 (KK6DCT B) and RPT2 (KK6DCT G) values was key to getting my transmissions sent out across the Internet gateway and to the reflector. I remember working this out before (link above), but this is key, as any of the other GRP * modes on the Icom 880 will not get your transmissions relayed out to the D-STAR network.

Once I had the above settings configured on my radio and transmitting on my Icom 880, I saw myself pop up on the REF001 activity last heard list, so we are looking good so far:

Just as I was typing this (8/14/18 12am local time), I heard JI3IBK (Op = Masa) call CQ on REF001. I returned his call, and we had a quick QSO and confirmed that my setup was good; audio quality was also good. So, I was pleased that it was all set up and working properly. I just had my first D-STAR QSO via my mmdvm hotspot!

The next steps are to solder the headers onto my new Pi Zero and move the mmdvm board from my Pi3 across to the zero. Then, I can put it in the custom aluminum case, and then my hotspot will be all set! 

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