There are various terms more specific to DMR that could cause some confusion. We hope to have covered them all. They are listed alphabetically to assist in finding them as you browse other pages however you may need to look up another term in the list that is used in an explanation. If you know of any we haven’t listed, please advise via the feedback form so we can add it.
Admit Criteria – This is a setting in the CPS that decides whether to allow your transmission to go out on a repeater thus helping to reduce “keying over” another user if the TimeSlot is busy. Unfortunately it does not work 100% on all radios which can lead to you being forced to leave a gap before being able to transmit.
Always On Talk Group – This is the opposite of “User Activated” where activity on a talk group can be heard without needing to be activated by the users (providing the talk group is available on that repeater).
Automatic Packet Reporting System (APRS) – This is a system which reports your position via analogue gateways and DMR repeaters, feeding into aprs.fi in order to show your position and movement. It’s not available on all radios and can be disabled. Note that not all DMR networks support APRS.
Channel – This is an entry containing details of a simplex channel or repeater – frequency etc. For DMR repeaters, you add a channel for each talk group on that repeater.
Cluster – This is a small group of repeaters in a region which have talk groups to connect them. More on these via the “Networks” menu.
Code Plug (CP) – This is the programming file that contains all the radio settings, repeater information, talk groups, contacts and other stuff to make the radio work. Some code plugs can be generated from CSV (Microsoft Excel) files which saves having to type in a lot of the information. For some radios there are also 3rd party editors to help with manipulating the code plug.
Colour Code (CC) – This is the DMR equivalent of a CTCSS tone using numbers from 0 to 15.
Contacts – This is user data against a DMR ID – your name, call sign and location. You can obtain this information to add into your code plug so that you can see peoples details on the screen otherwise you would just see their DMR ID. The number of contacts you can add to a code plug varies by radio. Some radios upload this to a different memory in the radio via a CSV file and can hold up to 100 000 contacts (there are around 160 000 contacts as at late April 2020).
CPS (Customer Programming Software) – This is used to read and write code plugs to/from the radio. Some CPS are better setup than others which makes a difference as to how easy it is to work on the code plug. Motorola CPS is not free but the majority of others are available via the manufacturers website. Also ensure to try use the latest CPS as there may be changes to improve different functionality. Some manufacturers such as Anytone will release an update package which will include the latest CPS and Firmware as well as instructions and other relevant documentation.
DFU Mode (Device Firmware Upgrade) – When doing a radio firmware update, the radio needs to be in DFU mode otherwise it could render the radio temporarily unusable until reloaded. Different radios have different ways of getting into DFU mode and therefore it’s best to find out first. It usually involves pressing one or two buttons whilst turning the radio on. Note that some radios such as the Anytone range, require a “MCU Reset” in order for the firmware upgrade to take effect. Once done, you need to reset the time zone, time, date and reload your code plug.
DMR ID – All users on the DMR networks require a DMR ID number which has their details attached to it. This is added into the code plug and also hotspots. You can register for an ID via this link (https://register.ham-digital.org/). Please note that it can take a few days for the ID number to be issued. You only need one ID and using more than one hotspot you can add an additional digit to the end of your ID to identify each hotspot on the networks. Note that should you get a new call sign or have a change of details request, there are about 30 local admins around the world who will take care of the registrations, changes and questions. You can contact your country admin with your query here https://register.ham-digital.org/contacts.php
Echo Server (Parrot) – This is a facility accessible via a few talk groups and reflectors for testing your audio and also checking access to a network or repeater. It’s also ideal for checking mic gain. The user puts out a call and maybe says a few words. A few moments after de-keying, the audio is played back. This only comes back on the specific talk group and is not played out over the network.
Hotspot – This is a personal low power simplex device that is connected to the internet (via LAN, Wi-FI or Mobile Data) and provides access to DMR and other digital networks (depending on the device) and use a variety of software to operate. This topic is expanded on under the “Hotspots” menu.
Experimental Firmware – Not sure why we still refer to this as experimental as it’s been around some time and is fairly stable. This is a 3rd party firmware (not available for all radios) which add’s extra features and tools such as a last heard list, dual backlight settings and the ability to upload the entire DMR ID database of contacts which is done by the firmware program. It’s very handy as it offers a function called “manual dial” for talk groups, reducing the amount of programming required. There are a few different versions – more on this under the “Experimental Firmware” menu.
Live Monitor (Last Heard) – This is via the internet or a mobile phone application where you can see the traffic on a network. This can be handy to see who’s on and where the activity is in regard to talk groups.
Manual Dial – This feature allows you to press a button then dial a reflector (or talk group if supported) using the keypad (pressing the PTT for 2-3 seconds to activate) therefore eliminating the need to have everything programmed in the radio. It’s best used for hotspots and Brandmeister (which has 1400 talk groups as at late April 2020).
MCC (Mobile Country Code) – This is a 3 digit code assigned to all countries. The first digit indicates rough geographical location. Europe is 2 and the UK is 234 and 235. You will notice that DMR ID’s are allocated based on this so you know the operator’s country. Wide area talk groups are allocated based on this (Europe is 2, North America is 3…) and Brandmeister talk groups all start with 235. Here’s a link to the listing – https://www.insys-icom.com/icom/en/knowledge-base/cellular/mcc
MCU – This is the Main Control Unit – the computer chip in the radio that’s responsible for running the most of the functions and services used. Many of the more recent models of radio, particularly Anytone, require that the MCU is reset each time the radio firmware is updated. This ensures that any changes that have been made to the system are correctly identified by both the radio and CPS.
MMDVM Repeater – This is becoming a more popular term due to progression of various bits of software. Pi-Star, which is a great bit of software for hotspots has become more popular as the driver behind many repeaters. Repeaters can be built using a case, 2 radios, a Raspberry Pi (usually a 3B+) running Pi-Star and several other bits of kit, making it a lot more affordable than commercial kit and it allows Keepers to change networks/modes and run dual networks/modes. 37 repeaters on BM UK and 17 repeaters on Phoenix UK are MMDVM. This is one reason for the breakaway from DMR-MARC, was to allow other repeaters to access networks and thus Phoenix UK came to life, still having a connection to DMR-MARC but allowing greater flexibility on the types of repeaters used (amoungst other features).
Networks – There are two main networks which allow local, regional, national and international connectivity – Brandmeister and Phoenix – more on these via the “Networks” menu.
Nuisance Delete – This feature (not available on all radios) allows you to temporarily mute a repeater/channel in the scan list.
Pauses – Due to various aspects of the mode, it’s vital to leave a 3-4 second pause between overs. Not only does it allow others to join in the QSO but (1) helps keep the link timing between the repeater networks and hotspot users (2) allows people to access another talk group on the same slot (3) allows users to unlink the reflector or talk group on a hotspot (4) allows for hold off timers to be terminated, to name a few.
Promiscuous Mode – This feature is not available on all radios. It allows the radio to pick up activity on any active talk group as long as you have the frequency and colour code in the channel. Anytone refer to this feature as “Digi Moni” – this function allows you to monitor a single TS or both TS then decide if you want to match the CC and/or TG.
Reflector (Ref) – These are similar to D-Star and Fusion rooms which can be manually dialled on most radios with a keypad using numbers from 4001 to 4999. Reflector 4000 unlinks you from any reflector you have been using. Using reflectors on DMR Plus will connect to various talk groups on the Phoenix UK network. On Brandmeister, not all reflectors are connected to talk groups [Note that Brandmeister plan to swithc off all reflectors by the end of 2020]. Just to note that reflectors on DMR Plus and Brandmeister are not linked – They may have the same number, but they are separate networks. When using a reflector, one goes to TG9 and manually dials the reflector to link. You then remain on TG9 to have a QSO.
Technical note: A Reflector is similar to a talkgroup in as much as it is a routing system, but this time the routing request/information, rather than being sent via RF into a repeater (though this is possible on some networks), it is transmitted via an internet connection from a Hotspot or similar. This time the routing request is sent as a one-off ‘Private Call’ to a network server which then detects it as a private call and subsequently routes the call to the designated location. Once the route has been established, there’s no need for the reflector routing request to be sent again and therefore the call reverts to its normal mode of operation – i.e. via the talkgroup applicable to the hotspot.
Roaming – A useful feature (not available on all radios) especially when mobile, which allows a user to roam across repeaters much like a mobile phone moves masts – all based on signal strength. Phoenix has specific talk groups for this referred to “Regional” talk groups between 801 and 880 however any talk group that is “always on” could be setup for roaming.
RX Group Lists – Now some people use these and some don’t as I believe for quite some time there has been a lack of understanding what they do. The easiest way is to advise how I have them setup for the Phoenix UK repeaters. I have 2 groups – “Phoenix TS1” and “Phoenix TS2”. Within each list are the talk groups applicable to each TS (time slot). Then when I create a channel (representing a talk group) for a DMR repeater, I link them to one of the lists depending on which slot the talk group is located. What this now does, if I turn to TG235 (slot 1) and activity comes up on another slot 1 talk group, it will pick this up and I can hear the traffic. Also for scanning, instead of needing to scan every channel for a DMR repeater (which exceeded the scan limit on many radios), I only need to scan a channel from each slot as each channel picks up transmissions from any active talk group on the slot.
Rx Only – This feature prevents you from transmitting on a channel – it’s ideal if you add in the PMR446 or other channels that you can legally monitor but not transmit on.
Time Slots (TS) – This allows the repeater to operate as two repeaters in one box thus reducing the bandwidth requirement on DMR. Various talk groups are assigned to a specific time slot. Brandmeister tend to use slot 1 for talk groups and slot 2 for reflectors whereas Phoenix UK use slot 1 for national/International and slot 2 for local/regional talk groups. A QSO can take place on both slots simultaneously without interfering with each other however only one talk group can be used on a slot at a time. There is a setting in the code plug to define which slot a talk group is on and only local TG9 is allocated to both as this talk group only goes out of the local repeater. More on this via the “Technical” menu.
Talk Groups (TG) – These are loaded into the contacts section of the code plug. They cover local, regional, national and international links much like a telephone exchange directing your QSO to a different location or number of repeaters depending on which you use. TG9 for instance does not link to any other repeater, TG235 covers all UK repeaters and TG1 covers all repeaters on the network worldwide. Just to note that talk groups on the various networks are not linked so TG235 on Brandmeister is not linked to TG235 on Phoenix UK. There are cases however where reflectors are linked to talk groups (DMR Plus and Phoenix), talk groups are linked to other modes (TG2351 on Phoenix is linked to Wires-X CQ-UK Room). There are a good many reflectors and talk groups on Brandmeister that are linked to other modes. However, there is no link between the various clusters, Brandmeister and Phoenix in the UK.
Technical note: A talkgroup (TG) is an integral part of the DMR network. It is essentially a routing information packet (Group Call) sent with the voice data everytime you press the PTT. Its purpose is to tell the network server which group you want to connect to and is usually sent from your radio to the repeater via RF and thence onto the network server.
User Activated Talk Group (UA) – These talk groups cannot be heard on a repeater unless someone activates them by pressing the PTT. As repeaters rely on the internet with some not on hardwired internet (they use prepaid dongles) and also to free up repeaters for others to use, its common practise not to have a lengthy QSO on wide area talk groups such as TG235 (UK Wide), TG1 (Worldwide), TG2 (Europe) and TG13 (English Worldwide) due to the vast number of repeaters that are linked to these talk groups thus User Activated (UA) talk groups can be used. An example is getting a contact on Phoenix TG235 which covers all repeaters on the network within the UK. Once the contact has been established, one can then move to a UK Wide UA talk group (TG80-84) to continue the QSO – this will limit the QSO to the repeaters you and the other party are using. It’s always best to key up and listen for a few moments to check if someone else is using the talk group. Either join in or go to another (there are 5 for the UK). Anyone else can join in or listen by keying up the talk group on another repeater across the UK. Talk groups that are not user activated are referred to as “always on” as you can use them and hear traffic without the need to press the ptt first to open the talk group.