DMR is an acronym for Digital Mobile Radio.
There are four operational areas to DMR:
The standard defines a two-slot TDMA channel access
method thus allowing two simultaneous voice or data calls on a 12,5kHz radio channel.
DMR was originally designed by ETSI for land mobile, commercial communications in the
66-960MHz band. This is evident in the user interface where numbers are used in lieu
of call signs. DMR modulates with 4FSK, indicating that it uses 4 frequencies
(compared to D-Star with 2 frequencies). This allows to double the data rate to 9600 bit/s.
The higher rate allows the transmission of 2 channels at the same time (2 time slots).
Be aware that you have to enter the talk-group number into the receive group list of many radios too, or your squelch will not open. This is a common error made by first time users and it is very frustrating.
The standard is divided into four chapters:
Australia has two server, located in a data centre somewhere in Australia.
Use the following links to monitor the status of the two core servers responsible for linking all repeaters currently supporting the VK-DMR network.
Talk Group 9, Time Slot 2 has a special use.
TG9-2 is used to dynamically select a specific reflectors. This provides access to the DMRPlus network of reflectors. A list of reflectors may be found at
TG9 on TS1 is local to an individual repeater. TG9 on TS2 is used to link an individual repeater to a reflector. In both situations, you would likely not hear anything unless you happened to be listening to that repeater.
To access reflectors, the radio must also be programmed with the TGs you are attempting to access
TG5000 checks your local repeater status. You then use the reflector number you wish to connect to as the tx TG – i.e. TG4400 for ref 4400.
Once you have connected, use TG9 to communicate via the reflector. TG4000 is used to disconnect your repeater from the reflector, or you can just let the reflector time out. Timeouts are normally set from 10 to 15 minutes after the last communication on that talkgroup.
Description Reflector TS Talk Group DMR DMR+ WWE 4629 2 TG91 2 TG9 VK-DMR 84800 2 TG8 505 4800 VK-DMR 84801 2 TG8 3801 4801 UNLINK 84000 UK Call 4400 2 TG2300 UK Chat 4401 2 TG2351 UK Chat 4402 2 TG2352 ????? 9900 2 TG9990 BM AUST 2 TG13 JA??? 2 TG53099
This table shows the North America DMR Talk Groups as defined by DMR-MARC Motorola Amateur Radio Culb) and their mapping to DMRPlus Reflectors. The DMRPlus reflector numbering system is an Open convention agreed upon by various interest groups.
|DMR+ Quebec (French)
|DMR+ USA (English)
|DMR+ Latin America (Spanish)
|DMR+ United Kingdom (English)
|DMR+ South Pacific (English)
|Southern Plains Regional
|Nova Scotia Provincial
|British Columbia Provincial
|New Brunswick Provincial
Examples of option stringsin the Options box on the configuration page: in the Options box on the configuration page.
The VK DMR network supports hotspots. Settings to join the VK-DMR+ Master server for connections into the VK-DMR Network: Dongles/openspot/dv4min 143/153 haven't worked for a while unfortunately. You can use TG9 on slot 2 to connect to any DMR+ reflector.i etc: • Server: he.vkdmr.net • Port: 8880 MMDVM etc • Server: he.vkdmr.net • Port: 55555 DMR+ reflectors are mapped to VK-DMR talk groups as described in the table below. Note that DMR+ reflector 4800 keys TG505 which is every VK DMR repeater. Hotspots can experience network latency due to the nature of the internet connection.
|VK DMR TG
|505 – VK wide
|3801 VK1 ACT
|3802 VK2 NSW
|3803 VK3 VICTORIA
|3804 VK4 QUEENSLAND
|3805 VK5 SOUTH AUSTRALIA
|3806 VK6 WESTERN AUSTRALIA
|3807 VK7 TASMANIA
|3808 slot 2 user activated chat channel
|3809 slot 1 user activated chat channel
Ben Fergus Goes back quite a way.
As far as I know the first amateur DMR network was DMR-Marc.
They started off Motorola only. Hence the name DMR- Motorola Amateur Radio Club.
They were very hostile originally to anything not Motorola. Very much against the general amateur ethos having a closed in system but at the time it was what it was.
Then along came DMR+ which allowed non Motorola repeaters. Hytera and then hotspots etc. It was more the network for experementing in the early days. However at the time you still only had commercial repeaters available so really it was still limited.
At some point DMR-MARC started to allow Hytera repeaters on the network but that was still only 2 commercial choices.
Then the major change was when MMDVM came along. It opened up the option of building a completely home brew repeater.
Around the same time along came Brandmeister and that gave a good network to run our new MMDVM repeaters.
The ethos of Brandmeister is in the name. A complete mix of brands and protocols on a completely open network and giving control to the repeater owners instead of all control being held by the network runners.
For quite a while DMR-MARC ignored Brandmeister and kept their closed ethos. But over time they kept loosing more and more repeaters and users to Brandmeister. Brandmeister grew at a huge rate simply because repeater owners wanted choice that DMR-MARC would not give them. A good percentage of repeaters were new MMDVM repeaters and another good percentage were repeaters poached from MARTC.
At some point VK-DMR forked away from DMR-MARC and I have seen a huge change in their ethos for the better since the split with a much more open network giving users much more choice.
I didn't think much of the VK-DMR network before the changes but since their change in ethos they have made some big changes which I respect.
This is an exciting time in digital radio with more choice than ever and do many avenues to learn and play with.
I have only concentrated on the main networks you will hear about, and it is a limited summary as I typing this on my phone while in a waiting room so I have left a lot out. But hopefully it gives you a bit of an idea of some of the history as I am aware of things.
OpenBridge is an open protocol to link DMR servers. Protocol designed in cooperation between BrandMeister team and Kurt OE1KBC.
OpenBridge is very simple protocol that allows to send call streams between servers.
Protocol is based on MMDVM protocol and supports DMRD packets only.
As with MMDVM hotspots, When using MMDVM repeaters to connect to DMR Plus
talkgroups, use TG8. Then to change reflectors, enter the Private Call
reflector code and transmit for a few seconds. An announcement through
the DMR Gateway will confirm the active reflector.
As a convenience, you can program the codeplug the keypad fast dial keys as follows:
The usual VK-DMR Net time is 0900Z on TG 5/TS1. The Net Controller and Co-ordinator is Peter, VK4NBL
Thanks to the tireless efforts of the co-rdinator, Peter VK4NBL, this net has become a pillar of the VK DMR fraternity in Australia and is very well supported with regular attendances close to the fifty mark.
Watch for announcements on Peters's Facebook page:
Peter selects a topic for discussion for each Tuesday night net and posts this on
The VK DMR Network Facebook Page:
Some local times for the net are:
UTC +8 AWST Australian Western Standard Time Perth Tuesday, 5:00 pm UTC +9:30 ACST Australian Central Standard Time Darwin Tuesday, 6:30 pm UTC +10 AEST Australian Eastern Standard Time Brisbane Tuesday, 7:00 pm UTC +10:30 ACDT Australian Central Daylight Time Adelaide Tuesday, 7:30 pm UTC +11 AEDT Australian Eastern Daylight Time Sydney Tuesday, 8:00 pm
IP Site Connect (IPSC) is a vendor specific repeater feature offered by
some manufacturers. Note that MototrboTM repeaters will only
interconnect over the Internet with other MototrboTM repeaters because it
is not part of the ETSI specifications and the manufacturers don’t want to
interconnect their infrastructures.
Motorola Solutions MototrboTM IPSC implementation allows up to 15
MototrboTM repeaters operating in DMR mode to be connected on a fully
meshed IP network, with one of the repeaters (or a c-BridgeTM) serving
as a Master and all of the others as Peers. Any traffic originating on one
of the interconnected repeaters is relayed over the IP network to each of
the other repeaters. The Peers will first establish a connection with the
Master and obtain the database of the other Peers along with their IP and
The more repeaters in this fully meshed IPSC network, the more IP network bandwidth required for each repeater. A single Peer connected to a Master requires 15 kbps for each time slot participating in the IPSC network, 6 kbps for link management, and 55 kbps for RDAC (Remote Diagnostics and Control) traffic; if both time slots are participating in IPSC, 91 kbps bandwidth is required; each additional Peer requires 36 kbps bandwidth. The Master requires an additional 3 kbps bandwidth for each Peer in the network. The MototrboTM System Planner has full details about calculating necessary bandwidth for repeater operators. To expand beyond the limits of basic IPSC network requires the utilization of a bridge to interconnect the different IPSC networks. These bridges require static IP addresses and larger IP network bandwidths than individual repeaters.
The c-Bridge TM supports individual managers for each repeater (micro- segmentation), which is an improvement over having the c-Bridge TM manager connected to a network of repeaters; this gives the ability to reduce bandwidth requirements and customize Talk Group availability for individual repeaters. The c-BridgeTM manager can serve as either a Master or Peer on an IPSC network. The c-Bridge TM allows for network connections to other IPSC networks, and other c-BridgesTM utilizing Control Center (CC) connections. The c- BridgeTM allows for the management of Talk Groups on an always-on, scheduled, or on-demand (PTT) basis. Models (upgradeable) are available to support 5, 15, 30, and 50 repeaters and they also support 100 CC connections between c-BridgesTM.
The c-BridgeTM also supports the interconnection of non-DMR audio sources utilizing an optional USB analog dongle and vocoder module. Remember, someone is paying for all of the infrastructure and monthly operating costs. If a club is operating your local DMR repeater, join and support the operation. If an individual is operating the local repeater, donate to support his ongoing expenses. Repeater operators should also be supporting their bridge operators. Besides the cost of the infrastructure equipment, there are also recurring monthly expenses for rent, utilities (power and Internet), insurance, and maintenance.
The specification for IPSC for the Home Brew DMR Repeater was initial written by DL5DI
and was based on specifications from Jonathan Naylor G4KLX for the repeater side.
Torsten Schultze DG1HT added requirements, and Hans-J. Barthen DL5DI added requirements
for the network/reflector side.
A copy of the specification is found here: DMRplus_IPSC_Protocol_for_HB_repeater.pdf (Local)
The purpose of analog bridge is to encode and decode PCM (analog audio) to AMBE
for use with https://github.com/n0mjs710/DMRlink and https://github.com/n0mjs710/HBlink.
Thanks to the work of Jonathan Naylor, G4KLX; Hans Barthen, DL5DI;
Torsten Shultze, DG1HT we have an open protocol for internetworking DMR
repeaters. Unfortunately, there's no generic client and/or master stacks.
This project is to build an open-source, python-based implementation. This is a
non-commercial license. Atribution is required if you use it.
For those who will ask: This is a piece of software that implements an open-source, amateur radio networking protocol. It is not a network. It is not indended to be a network. It is not intended to replace or circumvent a network. People do those things, code doesn't.
This work represents the author's interpretation of the HomeBrew Repeater Protocol, based on the 2015-07-26 documents from DMRplus:
The IPSC Protocol Specs for homebrew DMR repeater" as written by Jonathan Naylor, G4KLX; Hans Barthen, DL5DI; Torsten Shultze, DG1HT.
The DSD Wiki has lots of additional information about DSD including build
instructions and answers to the most frequently asked questions. The Wiki can base
be found here: https://github.com/szechyjs/dsd/wiki