Operating on a DMR-MARC repeater .. some basic notes.

Most, but not all UK DMR-MARC  repeaters are connected to the global DMR-MARC Network and not every DMR-MARC Repeater has all the same  Talkgroups  available, in fact it’s up to the repeater keeper which talkgroups they wish to carry.  As you look at the list of possible talkgroups  it is quite obvious that not every talkgroup makes sense to be carried on your local DMR-MARC repeater. There’s little sense in say, carrying a purely foreign language talkgroup here  in the UK for example., so you see a choice of relevant Talkgroups has to be chosen for the area the in which the repeater will be located in, pretty simple and logical stuff.

If, in the Morecambe Bay area there were a good number of Australian ex-pats – (there isn’t!)  it would be nice to carry, for example,  Talkgroups 5054 and 5056  maybe,  so they could talk back home., although I’d have to turn my DM4600 upside down …

Let’s talk a little more about where to operate, and on which Talkgroup, and why – and even why not – with some points to consider thrown in.. there are probably many more than i can think of here – so if you know better – Please let me know and educate me, as stated at the end of the post 🙂

If you want a main line to what’s happening try  Yahoo Groups MotoTrbo  (Yes, i think Yahoo groups sucks too)  and DMR-MARC’s Index page  which has some news and updates on it, athough i personally find it rather static and lacking in news, especially for British DMR-MARC users.

For GB7MB specific news there is this site (of course) and a Facebook site at GB7MB’s Facebook page  and in addition, there is a larger, but more general digital voice page on Facebook’s UK Digital Amateurs  which, at nearly 200 users may be among the biggest UK only DMR group on Facebook. The Facebook groups are run by same core people that run this site and also the GB7MB repeater.

First thing, the DMR-MARC network is in a state of flux, this is not necessarily a bad thing, it just means that it’s growing, and changing to meet the needs of it’s users, and in fact, i think it demonstrates the very flexibility of the technology, quite well.
As for  operating DMR-MARC, things that were deemed ‘fine business’ a few months ago, may not be anymore, and it’s important to understand why exactly. and ignoring what frequency this might be on, lets take a look at what a typical British DMR-MARC repeater might carry as it’s talkgroups.

Talkgroup 1       – calling,
Talkgroup 2       – Europe Continental,
Talkgroup 8       – regional repeater,
Talkgroup 9       – Local repeater,
Talkgroup 13      – Worldwide English, and
Talkgroup 235    – UK Wide.

As talkgroups can essentially be thought as virtual channels, lets rename these talkgroups for our discussion purposes here…

channel 1      – calling,
channel 2      – Europe continental,
channel 8      – regional repeater,
channel 9      – local repeater,
channel 13     – Worldwide English,    and again to
channel 235   – UK Wide

Talkgroup 1 (channel 1)
Now that it looks a bit more like what we’re used to, it then makes sense to see channel 1 as the worldwide calling channel, and, as with any calling channel, transmission lengths should be limited, here on DMR-MARC  it’s 2 minutes maximum (imagine a 2 minute CQ call on s 20 !)
You call on it, and if you get a response, you QSY away – as you would on any calling channel. Remember that when you TX on Talkgroup 1 (channel 1) be aware that you’re opening all other repeaters that carry that talkgroup worldwide  That’s why it’s really important to not hold a conversation on there !

Talkgroup 9 (channel 9)
All UK repeaters (that i’ve seen) carry this one .. and transmissions you make on here are NOT being sent to any other repeaters, it’s just like a normal, repeater without Echolink, IRLP or anything connected. a standard system like you are used to, but it’s DMR (so it’s better, right?)   Most traffic is on here, and this is where most locals hang out. Usual GB3-type FM repeater usage happens here. you can of course use this as any repeater, call for friends, have QSO, mobile, HTs, etc etc. That’s what it’s for 🙂

Talkgroup 8 (channel 8)
This is called the Regional Repeater talkgroup, not like Talkgroup 9, but it’s there for things like roaming and such like, maybe a few DMR repeaters connected together in a geographical area, like a common channel between GB7MB, GB7LP, GB7HM and GB7PN could be for example. Not much roaming is used in the UK, apart from a few instances in Yorkshire. It may become much more used as more DMR repeaters come on the network.

Now.. Where to go when you get a reply – it’s not always immediately obvious which talkgroup to move to (or change channel to) on DMR-MARC repeaters at first, but as a general guideline, use the smallest area coverage talkgroup that you and who you’re talking to have access to.

All new users make mistakes of course, and other more experienced users should go easy on new users and inevitable mistakes they may make, and if you hear someone on the wrong talkgroup, do not go in guns-blazing,  instead politely offer friendly advice on whats going on (or send them to read this)  – we’re only human, and we were all new users once over..  remember, was anyone impolite to You when you made a mistake as a new user ? if so, break the chain and be polite, or we’ll end up with repeaters full of people all too scared to TX on them..

But if you repeatedly hold QSOs on the wrong talkgroups, and willfully ignore advice given from the other more seasoned users, the Keeper, Sysop, or DMR-MARC Guys or people who run the gateways, you are spoiling the network for hundreds of other users – so dont be surprised if you get told off, or worse, as this is considered abuse of the system and network.

To Chat from (say) GB7MB in Morecambe Bay to someone in Blackpool, you would just stick to Talkgroup 9 – obviously there is no need to open other repeaters (by using abother Talkgroup (channel) up at the same time if your mate is also using GB7MB.

To chat from here on GB7MB to someone in London, Wales, Scotland, the Midlands etc – in fact any UK station out of RF range of our local DMR repeater, which TG should we choose ?
Well – talkgroup 9 is not going to be much use if we want to talk to someone in the Midlands (or wherever) because of course, our repeater ‘s RF up on 439mhz just wont normally carry that far of course, so we need a networked Talkgroup now  – so it’s an easy choice – UK Wide 235

To chat from GB7MB here to someone in sunny California, you could  use  TG 13 WorldWide English

To chat with Japan from GB7MB – you could choose TG 13 WorldWide English too – because unless you’re fluent in Japanese, you would be speaking to JA1XX in English .. so you get the idea.

For someone in Spain to chat to someone in Argentina, their local repeaters would likely both carry TG14 Spanish Worldwide,  and we’d never hear them here in the UK, as our repeaters do not carry TG14 ..    nor would it make sense to.

Imagine a foreign language local QSO, perhaps taking place between two stations in the same beautiful Spanish village, of course it’s no problem, they are on their local repeater, using their local, non networked talkgroup, and they could even go simplex.   Now consider instead, of them using their local talkgroup they change talkgroup to something that *is* networked, and wrong for that QSO  – like TG13 English Worldwide,  the QSO is now coming out of ever repeater on the planet that carries TG13 English Worldwide.
They shouldn’t be on that TG because,

A:   it’s not English,
B:   it’s not a worldwide QSO,
C:   it’s not even a European-wide  QSO
D:   it’s not even a Spanish country-wide QSO
E:   it’s not even regional – it’s all within one repeater

So as you see above, our example Amateurs should not be be using any other networked talkgroup, which here in Blighty, is what we use our TG9 Local for.

I Hope this makes a little more sense to talkgroups and things,  This is as i understand it, (and i’m not very bright) so please excuse any mistakes or incorrect information, as this is writen to try to help some new users a little bit . If you have any ommissions or obvious erriors i have made, MESSAGE me here at MBARS and i’ll correct this information as we go along. With apologies to all fictional Spanish DMR users. i could do with a holiday.


All work, text and images © GB7MB

21 Comments so far:

  1. You are more than welcome to link to the article. You may use the article as long as you link back to our site and give the appropriate credit to the author.

  2. Thanks Steve – glad it helped a little, there will be more articles coming soon. we aim to get at least one new post a week up here.


    • Hi Gary, Very nice of you to let us know our site may have helped a little.
      DMR is a very interesting mode, and many Amateurs are enjoying this mode and see it as the way forward, as many serious companies have invested heavily in the technology, and it’s growing and changing as users need, so it’s a far from extinct or dead-end mode, like some amateur only ones, so i think it’s a valuable mode to have access to, and should remain so into the not too distant future 🙂

  3. Thank you for a clear explanation of something I ‘ve been struggling with for a while! Now I feel confident enough to try DMR!

  4. good explanation answers everything for new commers this should be made known to all via magazine articles i,e Radcom and practical wireless ect lets get the knowledge out there

    • Hi Jim … That’s very kind of you to say, before we ‘went digital’ a few years ago now, we were unimpressed with the contradictions, obsfucation, half truths, country-specific and / or just plain misleading info spread across the many sites we joined and visited as we attempted to learn what we needed to, and in some small way, we vowed to filter the info and make it useful and valid for British Amateurs, and hope we could save them the time and headaches that we went through, and with an accessible style too. A few people have found our tiny site useful, and that’s great to hear, I’m not sure there’s quite enough useful information on here (yet) to warrant being referred to in the paper media, but they are welcome to point people here, we welcome feedback.. especially positive feedback Jim, I wish i had more time to devote to writing articles, but we will keep on doing what we’re doing… Thanks Jim !

  5. Hi GB7MB group. I am totally new to DMR,..I have just obtained an Anytone AT-D868UV DMR radio (retirement gift). I have managed to load the Moonraker codeplug files into it, by following an online manual, but other than that, I am a complete blank page as regards operating procedure on DMR. At my home QTH i can only access the Isle of Man repeater (the screen says CA TS1 CA Douglas ), and I can hear Calls and have answered them, but I’m lost when they ask me to move to a particular group/channel ??,…i have no idea how to do this, or even what the are, and difference between them,….how do I QSY to where they ask me?,….very confused,..de Ron G4FBC

    • Hi Ron !
      Welcome to the site, and i hope you’re making progress with DMR.

      When people program codeplugs, some names to certain things, like the channel name that is displayed on the screen – can be named to pretty much anything, it’s up to the person who made the codeplug, the same is true about the Talkgroup names (not their number) – though most are trying to be adopt to some kind of standard –

      Here is a link to a page giving you a list of talkgroups, and their uses.
      Phoenix Standard Talkgroupd

      In the case of your screen you tell us about, i’d say that ‘CA’ refers to the repeaters callsign – GB7CA
      and the TS1 means time slot 1 – there are two timeslots to choose from, but generally most channels or talkgroups on timeslot 1 are non-local – so are routed away from the repeater yu are working through, over onto a network of other repeaters which all carry the same talkgroup. Generally slot 2 talkgroup and channels are mainly local, though there are other talkgroups alocated to slot 2, but these are mostly just for neighbouring repeaters, so you can talk out of your local repeater to one of your neighbouring ones without jumping onto a timeslot 1 talkgroup – which are generally busier and for UK wide or international calls. It’s all about making the best, most efficient use of the 2 slot system … each DMR repeater can be thought of as a 2 channel repeater – like 2 completely different frequencies, both usable independently, but the really cool thing is it’s all done on one frequency – by switching between them very fast indeed so no-one notices – and 2 ‘virtual’ channels are formed out of one 🙂

      The ‘CA TS1 CA Douglas’ screen you mention doesn’t seem to give any information to which talkgroup it is set to.
      This is very important, because either you’ll not get heard at all, or your CQ call will be routed maybe to the wrong talkgroup, – so it’s crucial that codeplugs are programmed to display this, so you know where to aim your calls 🙂

      To my logic, a DMR rigs display should display, repeater, slot and talkgroup.
      for our repeater, we program our codeplugs to display ‘GB7MB Local tg9 s2″
      which on Phoenix repeaters, is where most like a normal FM repeater is, no other areas or connections, just local mobile-to-mobile GB7MB morecambe waffling 🙂

      For a QSO within the UK, but all connected DMR repeaters, It is customary to call on ‘UK wide calling’ (think all-uk s20) – so calling on UK wide opens up ALL DMR repeaters that carry the ‘UK wide calling’ talkgroup – so it’s only fair to ‘QSY’ to another talkgroup like the “talkgroup 80 UK-wide, user-activated” it’s a bit of a mouthful i agree, but it means you can both QSY to and can chat there without opening all the other repeaters up 🙂

      Many Many codeplugs I’ve seen are incorrect, wrong, badly set out or badly labelled or just confusing.
      There are a few articles on this site which may help a little Ron, please do let us know if we can help,
      though a local DMR repeater keeper or a local DMR user is much more likely to understand your requirements for DMR operation over in Douglas.


  6. Mark,….still confused,..really need someone to show me ‘hands on’ how to do this, nobody local to me has DMR,..nor any radio clubs near……only thing i’m hearing anything on is ”CA 235 UK WIDE CA DOUGLAS” above this, the display says ”DIG CH-1128 T1 R”

  7. Hi Ron,
    I shall try to find the Moonraker codeplug for the Anytone D868UV, and i shall have a look, and see if it’s okay for your area (as i see on qrz.com) although if i also saw on my radio’s display :
    CH-1128 T1 R I would also be confused, as CA refers to GB7CA, 235 refers to the Talkgroup (channel) but the CH-1128 T1 R seems meaningless to me.
    In the ”CA 235 UK WIDE CA DOUGLAS” – mentioning CA twice seems redundant, and if you know GB7CA is *in* Douglas, i think that’s irrelevant too, but that’s just my take on it.
    The 235 is the ‘Talkgroup’ – which, correctly, is used for inter UK usage, mainly like a calling frequency.

    I am looking at the GB7CA website now, and it shows which talkgroup (channels) they carry on there, here’s a list in the format (repeater name) (talkgroup number) (talkgroup name)

    CA 235 UK WIDE
    CA 1 Worldwide
    CA 2 Europe
    CA 13 Worldwide English
    CA 9 Local secondary
    CA 80 User activated UK wide
    CA 81 User activated UK Wide
    CA 113 User activated English
    CA 119 User activated Any language
    CA 123 User Activated Worldwide Any Language
    CA 822 User Activated Special link between CA, BR and PN
    CA 2351 User Activated Yaesu Fusion CQ-UK Wires-X Link
    CA 4400 User activated to DMR+ reflector 4400 (10 minute timeout)

    Timeslot 2
    CA 9 Local Primary

    CA 801 link to South East repeaters . (AK, AS, CK, CF, CL, CT, EK, EP, EX, GF, HA, HR, IK, LO, NS, SC, SE, SK, TH, WL, WS)

    CA 810 linked to South West repeaters (AV, BK, CT, EL, FI, IT, KM, SU, TC, WL, WW)

    CA 820 linked to the North-West repeaters (BR, CA, FO, HM, LP, MB MR, PN,)

    CA 830 linked to Midlands repeaters . (CT, FW & SK)

    CA 840 linked to East England repeaters
    (AL, CL, CT, DS, FU, HA, MK, ND, PE, PY, SK, WS)

    CA 850 Links for Scottish repeaters

    CA 860 linked to North East England repeaters (HS, HX, LE, RE, RV, TD)

    CA 870 linked toWales and Marches repeaters (HM, PN)

    CA 880 linked to Northern Ireland repeaters (OM, HB, LY, UL)

    CA 9990 is a special test channel, where you can test your audio,
    which replays what you transmit back to you.

    there are a few more, and it’s bit of a complicated looking list i grant you, but if you break it down, it’s pretty logical.

    To put a call out for another local on the GB7CA repeater you would use CA 9 local (primary) and, to call CQ all over the UK, you would shout up on ‘235 uk wide’ – then both change to another, like 80 user activated.

    If the channels are named something different, that’s up to whoever wrote the codeplug, if you know which repeater you are on, the talkgroup is the most important thing to know.

    Not sure if the TDMA and timeslot thing makes sense, it’s a pretty abstract concept for many of us, but it may be less confusing to just think of the 2 ‘timeslots’ DMR has, as being a completely separate repeaters.

    The talkgroup is the thing we’re interested in, it’s simple enough once you know it’s just a bit like a way of organizing radio traffic just like CTCSS or different groups on a communal FM repeater.

    Why different talkgroups matter is you get different users on each, different talkgroups can be routed across the internet, into other repeaters or into computer servers and dongles and hotspots, some aren’t routed at all, and just stay on the repeater like an unconnected FM repeater used to be (like when i started in the late 70s!) – these talkgroups which stay on the repeater only are called (usually) Local and for some obscure reason i still can’t fathom out, are on talkgroup number 9 (maybe they were fans of the Beatles)
    What goes on talkgroup 9, stays on talkgroup number nine !

    I think i may have to do an article to illustrate this a little better, it will take a while to do the graphics though, but i’ve wanted to, for a while now.


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