New to DMR; need a little help understanding some basics

kn4vqy
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New to DMR; need a little help understanding some basics

Post by kn4vqy » Thu Jan 02, 2020 7:54 pm

Hi all,

As the title says: I'm new to DMR. I used the factory firmware for a bit, which was fine, but started using openGD77 on recommendation of a friend. I love all the extra features, but I just can't figure out something that is probably basic to everyone.

I have programmed channels into my home hotspot zone and a couple of local repeaters. When I am in a zone I can hear talk from *any* talkgroup, which is kind of cool. But what if I want to just talk in *one* talk group and not hear the others? I feel silly, but haven't figured that out yet.

Thanks in advance!

Mike

edit: adding my codeplug
GD-77 KN4VQY 01-02-2020.dat
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G4EML
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Re: New to DMR; need a little help understanding some basics

Post by G4EML » Thu Jan 02, 2020 10:25 pm

The current OpenGD77 firmware does not have the ability to filter talkgroups yet. This is something that may be implemented in the future.

However even if it did have this facility it may not do what you are expecting.

DMR has two timeslots and each timeslot can only transmit one talkgroup at a time. (in the case of a simplex Hotspot there is only one timeslot.)

If your repeater or Hotspot is sending out multiple talkgroups on a timeslot then nothing you can do with your radio will stop that. It can only send one at a time and this is normally done on a first come first served basis. You could possibly mute the talkgroups you didn't want to hear but your repeater or Hotspot would still be sending them and occupying the timeslot so you wouldn't hear anything during that time.

The only way you can change this behaviour is by modifying the 'always on' talkgroups that your repeater or hotspot is configured with. In the case of a repeater this has to be done by the repeater owner. In the case of a hotspot it has to be done on the self management web page of the network.

VK3KYY
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Re: New to DMR; need a little help understanding some basics

Post by VK3KYY » Thu Jan 02, 2020 11:40 pm

Colin

Thanks.

I think its a common misunderstanding that with a hotspot or a repeater that somehow it transmits all TalkGroups and you can choose on the radio which TG you want to listen to.

This is not the case.

DMR MARC repeaters are normally configured only to one or two TalkGroups per timeslot.

e.g. My local DMR MARC repeater is configured for TG 505 and TG 3803 on Timeslot 2, and TG 5 and TG 8 on TimeSlot 1.

In this configuration, if there is traffic on the network on both TG 505 and TG3803, its first come first served on TimeSlot 2, so I don't get to choose which QSO I can hear, its just whichever the repeater is transmitting.

Hence filtering on TG 505 in this instance if the active QSO was on TG 3803 would just result in me hearing nothing, even though there is a QSO on 3808 being transmitted.


If you run a hotspot and connect to the Brandmeister network, you can configure the Brandmeister server to route multiple TG's to your hotspot, but the same First Come First Served principal applies.

e.g. If you setup both TG 91 and TG 505 to be routed to your hotspot, you'll find that because TG 91 is a very active worldwide TG, that you will end up only hearing TG 91 because the traffic won't stop for long enough on TG 91 for the network to re-route any potential QSO's on TG 505 to your hotspot.

Hence you'll find that most people with hotspots only set one static route TG, and just change this route if they want to listen to another TG.

With BM, on simplex hotspots, they have a shortcut system where transmitting on TG changes the routing to that TG, but its not very reliable and often the routing reverts back to an old TG you were listening on a few minutes ago.

G4EML
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Re: New to DMR; need a little help understanding some basics

Post by G4EML » Fri Jan 03, 2020 1:03 am

There is a legitimate reason to filter talkgroups on the radio but it is more to do with not being disturbed than selecting what you hear.

If for example your local repeater has both local and country wide talkgroups always active and you are waiting for a call from a local station you may wish to monitor for local calls only and not be disturbed by the wide area conversations.

NA7Q
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Re: New to DMR; need a little help understanding some basics

Post by NA7Q » Fri Jan 03, 2020 1:45 am

I don't always want to have my radio silenced to a single talkgroup. But it is a GOOD idea to have this ability to do so.
Some folks don't want to be disturbed by having to hear all the full time TGs, or having to hear TGs others may key up on the repeater.

My repeater is part of a 60 repeater large area network. Every repeater has at least 1 or 2 (or more) full time TGs per slot. So some folks want to only monitor Local 1. But if they have to hear it all, they'll be hearing all the full time TGs, Local 1, Washington 1, Oregon 1, Cascades East 1, PNW 1, and potentially something else that gets kerchunked on the repeater for the PTT TGs. Same story for slot 2. It at times can be busy, and many of us want to, or do turn off radios when we can't silence them with listening to only a single TG, but we'd like to still listen to that one TG without the extra traffic.

I think if there could be future improvements, this would be a good one. Just my 2 cents.

kn4vqy
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Re: New to DMR; need a little help understanding some basics

Post by kn4vqy » Fri Jan 03, 2020 3:12 am

After reading your reply, I watched the little screen on the MMDVM hotspot. It said "listening to XX" where XX was the talkgroup number. Usually it is listening to TG 91 (WW) because it has so much traffic. I switched to another TG, waited for a break in chatter, then keyed up to the other TG. This caused the hotspot to listen to that TG instead. Seems like problem solved. But I don't know how it will behave on a local repeater yet. Am I doing things right? Is this what everyone else is experiencing?

Mike

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m1dyp
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Re: New to DMR; need a little help understanding some basics

Post by m1dyp » Fri Jan 03, 2020 3:19 am

I do this on my hotspot. it seems to work fine, no local repeater here
73 de Ken :D

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kd2lh
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Re: New to DMR; need a little help understanding some basics

Post by kd2lh » Fri Jan 03, 2020 3:23 am

The talkgroups routed by the voice over IP infrastructure (like Brandmeister or DMR-MARC) can be either dynamic or statically configured.

In Brandmeister, this is done through one of their browser interfaces associated with the hotspot. Using a key, some hotspots (like those running PiStar) allow you to control this from the hotspot admin dashboard itself.

When the hotspot is configured statically for a talkgroup, it is always forwarded by the VOIP infrastructure.

When the hotspot is operating dynamically, and it receives incoming RF for a given talkgroup, that talkgroup will continue to be forwarded by the VOIP infrastructure to the hotspot through the conversation and not reset until there is no local RF activity on that talkgroup for a timeout period.

Repeaters are generally configured by the owner to support specific talkgroups on their two timeslots. Note that the timeslot is a repeater to radio or hotspot to radio RF link characteristic, and not something configured within the VOIP infrastructure.

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m1dyp
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Re: New to DMR; need a little help understanding some basics

Post by m1dyp » Fri Jan 03, 2020 6:02 am

:D :D :D
73 de Ken :D

VK3KYY
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Re: New to DMR; need a little help understanding some basics

Post by VK3KYY » Fri Jan 03, 2020 7:18 am

kd2lh wrote:
Fri Jan 03, 2020 3:23 am
When the hotspot is operating dynamically, and it receives incoming RF for a given talkgroup, that talkgroup will continue to be forwarded by the VOIP infrastructure to the hotspot through the conversation and not reset until there is no local RF activity on that talkgroup for a timeout period.
On BM with a Simplex Hotspot, the default seems to be an infinite time-out on the TG assigned by transmitting on that TG.

However with a Duplex Hotspot (on BM) there is a definite time-out period, but I don't know what the default value is.

IMHO. The BM dynamically allocated route system on Simplex Hotspots is somewhat buggy, as if you change TG and transmit for a second or two, the dynamic route will appear to have change, and you can sometime even transmit an over of 30 seconds or more, only to find that in the next minute, the dynamically allocated TG reverts back to the TG prior to the TG you are currently on.
This bug/feature causes a lot of confusion on BM.


Even using the BM Selfcare dashboard to remove a dynamically allocated TG, e.g. TG91, its very common for that dynamic route to be reactivated within 30 seconds, and you end up hearing the traffic on TG 91 again.
And it can take multiple attempts of removing the TG91 dynamic route from the Selfcare dashboard before it finally stops routing that traffic to your Hotspot.

Also. On the BM Selfcare dashboard, if you roll over the dynamic route with your mouse, it shows a message saying that transmitting on TG4000 will remove the dynamic route. However this has never worked for me.

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