The Australian amateur radio DMR repeater network

Author: vk4du (page 1 of 5)

Welcome VK3RCQ Bendigo

Welcome to VK3RCQ Bendigo.

147.325 +0.6

Thanks to VK3WG and VK3TE

Maximising network efficiency

Slots and talk groups

One of the great advantages of DMR is its ability to support two simultaneous conversations on one repeater using Time Division Multiple Access (TDMA).  The two slot TDMA system is unique in amateur digital modes.

Our DMR network has many talk groups spread across the two slots.  Some of these are static – i.e. always on, and some are User Activated (UA) – they need to be keyed (“kerchunked”) up, and time out after a period of inactivity (normally 15 mins).

You can see the static groups on the IPSC server web page: http://rpt.vkdmr.com/ipsc/

The static groups are shown in the 5th and 8th columns alongside each repeater.

There are a lot of talk groups, and they can be confusing.  They are described at https://vkdmr.com/using-dmr/

Network loading

Although the network is quiet during the day, the user base has increased significantly (and continues to do so), so there will be occasions where there are two, sometimes three groups of users trying to use both time slots.

When user numbers were low, it didn’t really matter if you used a static talk group, but these days, a static group can hold up a time slot and make the network difficult to use for others. 

This is particularly the case with the State based 380x series talk groups on time slot 2.  If two stations are talking on, say, 3802, it locks the slot onto 3802 for all VK2 repeaters – other VK2 users are unable to use the main calling talk group – 505.

Whether you are accessing the network via a repeater or a hotspot, you should use talk groups that key up the minimum number of repeaters if you wish to chat with another station after QSY’ing off 505 – this will ensure that the maximum number of users can access the network.

If you are working a station on the same repeater, use TG9 on time slot 1 – this only keys the one repeater on one time slot.

If you are using two separate repeaters, switch to a UA talk group.  Most UA talk groups are on time slot 1, but there is one available on slot 2: TG3800.

As with all UA talk groups, TG3800 only connects the repeaters used in the contact – this keeps the other repeaters free on time slot 2 for stations to call on the main VK calling “channel”:  TG505.

UA “chat” talk groups are listed below:

TG53 TG3800

*3810 is intended for WICEN but is available for general use outside WICEN activities.

If possible, it is always handy to have the IPSC server web page running on a PC/tablet/phone – this gives you an overview of network activity.

TG5 on time slot 1 is a special case – it is intended for national broadcasts and nets, so is intentionally static.  It should not be used for other traffic.

Welcome VK4RJW Rockhampton

Welcome to VK4RJW Rockhampton.

438.8125 -7

Thanks to John VK4UE

Welcome VK2RCN mid north coast

Welcome to VK2RCN, Port Macquarie.

438.425 -5

Fills in a big hole on the NSW mid north coast.

Another repeater provided under the AR NSW Radnet project.


Thanks to AR NSW, Matt VK2FLY and the Oxley region ARC.

Welcome to VK3RYN Yallourn North

New VK3 repeater at Yallourn North has joined the network.

438.725 -7

Thanks to VK3AJ and VK3TE.

Welcome to VK4RBU Bundaberg

438.1 -7

Thanks Andrew VK4QF and the Bundaberg ARC.

Welcome to VK2RAG, Central Coast NSW

Welcome to VK2RAG, Gosford NSW.

Another repeater donated by AR NSW.

Well done to ARNSW, the Central Coast Club and Matt VK2FLY

438.85 -7

Welcome VK2RGL Forster

Welcome to VK2RGL, covering Forster/Myall Lakes in NSW.

The repeater was supplied as part of the AR NSW grant program – many thanks to AR NSW and Matt VK2FLY.

439.775 -5

Welcome VK4RSB, north Cairns

Welcome to VK4RSB, Trinity Beach, north Cairns.

Thanks to Steven and the team from the Cairns ARC.

438.1 -7 MHz

The repeater shares TG8 with VK4RBK Atherton.

Welcome to VK3RSA

VK3RSA at Emerald, Vic (eastern Melb.) has joined the network.

438.8 -7

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