Tim's DMR (Digital Mobile Radio) Notes and Useful Web Links

A plea to DMR operators around the world:

  • PLEASE set your mic gain / Tx audio level! You can monitor yourself on Brandmeister. Try to get your audio into the green bit on the level indicator. Very many people have hopelessly quiet audio and one or two have end-stopping audio. This makes listening to two or more people very difficult - constant messing with the Rx volume and getting your ears blown off, particularly when wearing headphones!
  • PLEASE try to avoid holding long QSOs on wide-area calling channels, most DMR help sites include reminders of this. I did this once or twice when I was new to DMR, and now I feel guilty!

    • 14.05.2022: Firstly a huge thanks to the many website authors who have tried to explain DMR for the benefit of novices. I am a professional engineer and it still took me around 2 weeks to get comfortable with what was going on. I believe this was to some extent due to me not finding a website that explained the key concepts of DMR, in particular that it is talk-group centric, not RF frequency centric like conventional radio. I will produce a picture that shows the DMR connection hierarchy in a way that should help new people to get their head around it quickly.

    Codeplug Stuff for DMR Repeater GB7PY at Madingley, West Cambridge

    21.05.2022: GB7PY is connected to the UK Phoenix network and it has taken me ages to figure out exactly what the repeater can do on TS1 and TS2. There is general documentation on https://www.dmr-uk.net/index.php/layout/ showing 'typical' TGs used on the 2 timeslots, but there is no guarantee that this is what the local sysop of GB7PY has actually done in terms of TG to TS mapping and which TGs are statically linked.

    By trial and error, and watching activity on the Phoenix-k Live Dashboard and Phoenix-a Live Dashboard I have concluded the following:

  • On TS1 you can access TG 1, 2, 13 and 235 (statically linked) as well as TG 2350*, 2351, 80, 81, and 82 (user linked and last for 15 mins).
  • TG2350 appears to route through to Brandmeister (why?) but all of the other groups seem to be local to Phoenix.
  • TGs 235 and 2351 seem to be unrelated to those on Brandmeister despite the TG numbers being the same.
  • On TS2 you can access various Phoenix TGs, such as 830, 840, 841 and probably others. These are again local to Phoenix (no link to Brandmeister).
  • Conneting to non-Phoenix TGs through TS2 does appear to route through to Brandmeister. This is useful.
  • This includes TGs 235, 2350-235x, i.e. this will connect to the Brandmeister version of these TGs.

    • Codeplug Stuff for a Half-Duplex HotSpot connected only to Brandmeister

    My HotSpot consists of an old Raspberry Pi model B+ (single core, from 2014) with a 'Jumbo' MMDVM hat from ebay. Software is Pi-Star. I have elected to use 438.8 MHz for both Tx and Rx and to use TS2 for everything.

  • It is possible to connect to any Brandmeister TG simply by programming a channel on your radio with the HotSpot RF parameters and the required TG.
  • I have not yet found any Brandmeister TGs that route through to the Phoenix network.

    • More to come...

    Last updated: 24.8.2022