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.

Examples:
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.

-Hax-

All work, text and images © GB7MB

17 Comments so far:

  1. 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.

    -Hax-

    • 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 🙂

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

  3. 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 !

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