Digital Mobile Radio (DMR) Primer
April 14, 2023
- Tom Janke N8TJ
- Stan LaMuth WB8QJZ
- Steve Sutton KC8WXM
- Dana West KC0MYP
- https://dmrtechnet.net/
To begin with DMR, you need an FCC license for Amateur Radio (HAM) –and to get that you will need an FRN number as that is the way that the FCC looks at individuals. https://www.fcc.gov/wireless/support/universal-licensing-system-uls-resources/getting-fcc-registration-number-frn
Then you will need to study for and take 1-3 test(s) for your License (Tech, General, Extra) www.HamExam.org www.HamStudy.org
You may take all the exams at once or progressively over time. Volunteer Examiners who already are HAMs (VE’s) administer the tests. After passing the test(s), a Call Sign is assigned to you within 1-3 weeks.
Once you have a license (DMR is fully available to a Technician or above), then you will need to register for a DMR ID (can be issued the same day or take up to 3 days to receive) at www.RadioID.net
With your CallSign and DMRid in hand, you can then go out to the BrandMeister (BM) website and sign up for an account there. https://brandmeister.network/
Once you are notified that you are active (this is a voluntary organization and so it is not necessarily quick, although it usually is same day), you will want to go to the SelfCare tab and turn ON your HotSpot security and create a HotSpot Security Password (different from your BM password –think simple, ie., all uppercase, or all lowercase. or all numeric -one or the other/not mixed).
DIGITAL MOBILE RADIO NETWORKS
This is one area where DMR is a bit different from D-STAR. Just as in the D-STAR playground, some DMR repeaters are standalone and used for local communication only; however, DMR and D-STAR diverge in how they handle it when repeaters are interconnected.
In D-STAR, repeaters can be linked to reflectors. In DMR, repeaters using static talk groups are linked together in network configurations that are decided by the system administrations, which can’t be changed by individual hams. Some repeaters also allow hams to temporarily subscribe to specified dynamic talk groups.
DMR-MARC and DMRPlus (DMR+)
Initially, there were two main worldwide umbrella networks for amateur radio, DMR-MARC (which years ago was the largest), built on MotoTRBO products, and DMRPlus (DMR+), built on Hytera products. The two networks didn’t interconnect initially. Eventually, the two teams started collaborating on building some interconnectivity, but the use of these two networks hasn’t been growing as much as some of the other newer networks in recent years.
Brandmeister
More recently, a new worldwide network, Brandmeister, was launched. It grew to be the largest amateur radio DMR network in the world. Brandmeister users can key up to (a.k.a., temporarily subscribe to) and use any talk group. It’s also a very friendly network for hotspot users.
On the Brandmeister wiki, they say:
“If you are an amateur radio operator working in digital voice modes like D-Star, DMR, C4FM, APCO25 or others (not all are supported yet!), you do not need to know much about Brandmeister, and it’s very easy to operate on its infrastructure.”– Brandmeister Network Admins
“Brandmeister” is a play (in German) on the words “brand new master server.”
It’s a decentralized, worldwide, community-driven network being developed by an international team:
| Master | Domain | Location | Donations | |
| 3102 | 3102.repeater.net | Dallas, Texas | Donate | |
| 3103 | 3103.repeater.net | San Jose, California | Donate | |
| 3104 | 3104.repeater.net | Chicago, Illinois |
They are joined by teams in countries worldwide that are bringing master servers online, as well as by other teams putting repeaters online. As of July 2019, there are 47 BrandMeister DMR Servers deployed, connecting hundreds of repeaters in more than 43 countries.
As of early 2017, BrandMeister was just a bit more than a year old: development work began in 2014, and the first master servers went online in November of 2015. It’s spreading as fast as a wildfire, which I guess is appropriate since, in German, “Brandmeister” (little “m”) means fire chief.
From the Brandmeister wiki:
BrandMeister is an operating software for master servers participating in a worldwide infrastructure network of amateur radio digital voice systems.… Brandmeister allows you to connect to MOTOROLA DMR-MARC and Hytera DMRplus networks, this means you can operate with other DMR amateur radio operators on both infrastructures at the same time.
Brandmeister has a really nice, robust User Dashboard that includes activity meters and a real-time “last heard” page.
TGIF Network
Another relatively new network is the TGIF network. It has a small but loyal following with hams around the United States.
TIME SLOTS
When there are so many puzzle pieces that need to be fitted together to set up a DMR radio successfully, it’s challenging to figure out where to begin.
DMR uses Time Division Multiple Access (TDMA) to generate its signal instead of the Frequency Division Multiple Access (FDMA). Specifically, DMR uses 2-slot TDMA (the slots are numbered 1 and 2, or TS1 and TS2).
What this means is that calls on two different channels can share the same frequency simultaneously. Each call is sliced up into chunks of a few milliseconds, and the slices from the two calls are interleaved on the signal. This happens so fast that we hear what we perceive of as a continuous transmission even though it’s coming in chunks, looking like this:
This also means that when you program a DMR channel, you must specify both the frequency and the time slot, so that your radio and the repeater can encode and decode which chunks on the signal belong to the channel you’re using.
COLOR CODES
Another fundamental piece of the puzzle is color codes (CC). Think of the as the digital version of a PL tone like you find on analog repeaters. When you want to use a DMR repeater, you need to program in the appropriate color code to open it up and have the repeater respond that it’s hearing your transmission. There are 16 color codes, 0 – 15. Why are they called color codes? Nigel, G8IFF educated us on the answer:
“[I]n the early days of DMR being a Motorola commercial system, the radio programming was done by Motorola who sold you a “plug” containing diodes that you plugged into a socket on the radio’s circuit board. No user programming in those days. The color code was so called because it was indicated by a colored dot printed on the code plug you were supplied with.” Nigel, G8IFF
Just as with analog radio CTCSS tones, you need to get the appropriate color codes from the organization operating the repeater in order to be able to use the repeater. When you program a DMR channel, in addition to the frequency and the time slot, you must specify the color code; otherwise, you won’t be able to access the repeater.
The magic formula to accessing a DMR repeater…
Frequency + Time Slot + Color Code
Let’s take a look at an example of a local Lansing, Michigan DMR repeater.
Frequency: 442.0875 (+5 MHz)
Color code: 1
Time slot: 1
The above programming will get you onto the wide-area MI State time slot 1 of the KB8SXK repeater located on top of the old McLaren Hospital on Greenlawn Avenue.. It’s a part of the Mi-5 system.
Frequency: 444.7875 (+5 MHz)
Color code: 2
Time slot: 2
The above programming will get you onto the KB8SXK time slot 2 of the Lansing repeater located on top of the old McLaren Hospital on Greenlawn Avenue. This repeater is also a part of the Mi-5 system.
TALKGROUPS
Finally … let’s talk about talk groups!
Of course, the whole point of getting onto a DMR repeater is to talk to other hams, and you do that by visiting a talk group, which enables one-to-many communication, sort of like a conference call or a chat room. Anything transmitted to a talk group is transmitted to everyone listening to (linked to) that talk group.
There are worldwide, nationwide, regional, statewide, area, and local talk groups, as well as language-based talk groups. For example, on Brandmeister:
- Talk group 91 is Worldwide
- 93 is North America
- 3100 is U.S. Nationwide
Note: 3100 is an example of a talk group that is bridged across networks; it is U.S. Nationwide on the DMR-MARC, DMR+, and Brandmeister networks. - 3126 is U.S. State of Michigan
- 3169 is U.S. Midwest Region
- 9 is for using local communications on a single repeater
- 2 is used when repeater owners decide to link multiple repeaters in a region together
In addition, there are the TAC (Talk Around Channel) channels (U.S.: 310 – 319; worldwide: 901 – 903). TAC 310, 311, and 312 are bridged between different networks, and Brandmeister is a guest on these channels. Hams that want to have longer chats in order not to tie up main channels that are more widely shared can use the TAC channels.
But what about the difference between static talk groups and dynamic talk groups?
Talk groups are either static (always activated) or dynamic (user-activated). When you activate a dynamic talk group on a repeater’s time slot by keying up, it typically remains activated while there are transmissions on it, then drops from the repeater after some period of inactivity, for example, after 10 or 15 minutes. You don’t need to manually unlink from a talk group.
When you’re using a simplex hotspot on the Brandmeister network, there also are auto-static talk groups that you can setup on your hotspot. For more info, see the article Brandmeister dynamic, static, and auto-static talkgroups.
On many repeaters in Michigan and across the country, the talk groups you can use on a given time slot are specified by the repeater administrator, including any dynamic talk groups you want to use. Please see MNDMR talk groups to understand how most MNDMR repeaters are programmed and what talk groups they allow on TS1/TS2. If you want the freedom to use any talk group you’d like, you might want to invest in a Pi-Star hotspot.
The Pi-Star website also hosts a current and complete Brandmeister Talk group List, including descriptions and a link to the Brandmeister Hoseline page, where you can listen to activity. Wondering what hoseline is? https://hose.brandmeister.network/ is live audio feed database where you can monitor any talk group on Brandmeister using your computer, tablet or phone but you’re unable to talk. You can only listen.
ZONES
Zones are an organizational tool, like file folders, for the channels in your DMR radio; in other words, a zone is a group of channels.
The channel selector on many DMR radios lets you choose from 16 (or more) channels. In order to get past that limitation, you can use zones. For example, a typical DMR radio that could handle 64 zones capable of storing 16 channels each, for a total capacity of 1,024 channels.
You can organize your zones however you want, for example, you might want one or more “Home” zones for channels that correspond to your favorite talk groups that you can reach via the repeaters that are within range of your home. You might want a “Commute” zone that corresponds to the talkgroups you most often use via the repeaters that are in range as you drive to and from work. If you use a hotspot, you might want some “Hotspot” zones for the talkgroups you key up via your hotspot. You might want some other zones that correspond to the groups of talk groups your club uses, or to nets you frequently participate in. Some people set up zones based on repeater locations.
It’s pretty easy to use zones: you create a zone, name it, and then add channels to it. Optionally, you can change the order of the channels within the zone.
SIMPLEX FREQUENCIES
Just as you can use analog transceivers in FM mode, you can use DMR-capable transceivers to talk directly from radio-to-radio simplex. These are commonly used North America DMR simplex frequencies and are recommended for all DMR users in the United States to have programmed:
Admit criteria: Always or Channel Free
Time slot: 1
Color code: 1
Talkgroup ID: 99
UHF simplex channels:
- 441.0000 MHz
- 446.5000 MHz
- 446.0750 MHz
- 433.4500 MHz
VHF simplex channels:
- 145.7900 MHz
- 145.5100 MHz
DMR NETS
A good resource for finding DMR nets across the United States is the Ham Radio DMR Nets Telegram group. It has a quite comprehensive list of active DMR nets. Each net is displayed an hour before it goes live, making it easy to find out what’s currently on the air: https://t.me/HamRadioDMRNets
CODEPLUGS
“Codeplug” is a common name used for a radio configuration file that sets the frequencies, color codes, timeslots and talk groups into channels which are organized into zones. Code plugs can be shared to minimize the time and errors to configure a radio. Michigan-focused code plugs for popular radios are available here.
DMR Nets in Michigan:
- Monday 7:45pm-8:30pm DMR Tech Net on TG-3126
- Monday 8:30pm-9:15pm Michigan One DMR Net on TG-3126
- Monday 9:15pm-10:00pm Post DMR Tech Net on TG-TAC310
- Saturday 7:00pm-7:15pm Arrow DMR Net on TG-3126
- Sunday 6:30pm-7:00pm UP Net on TG-31268
Michigan DMR Talk Groups:
TG-3126 Michigan statewide
TG-31260 Michigan WX/ARES/EmComm
TG-31261 Mi-5 Statewide 1
TG-31262 Mi-5 Statewide 2
TG-31263 Mi-5 Event 1
TG-31265 Mi-5 Event 3
TG-31267 West Michigan Talk Group
TG-31268 Upper Peninsula Talk Group
TG-31269 West Michigan Technical Group
DMR Resources:
https://www.michiganonedmr.net/ to find Michigan Brandmeister repeaters & it’s a good DMR resource
https://dmrtechnet.net/ a good DMR resource
https://radioid.net/ to request a free Digital Radio ID & update your digital contacts list
https://brandmeister.network/ good resource guide to Brandmeister repeaters
https://support.bridgecomsystems.com/product-support good support page for Anytone radios
https://www.repeaterbook.com/ to find Michigan DMR repeaters (listed later in this document)
https://www.radioreference.com/ to find Michigan radio frequencies (Police, Fire. Air, etc)
https://www.youtube.com/@BridgeComSystemsInc
https://www.youtube.com/@HamRadio2
https://www.youtube.com/@HamRadioCrashCourse
https://www.youtube.com/@ARRLHQ
https://www.youtube.com/@HR4NT
https://www.youtube.com/watch?v=ts2nkCDIS4s&list=PL0R9jy9LZw_2Je-1Td9Xb2S8-Vl_bFTGG
This book is a guide to Digital Mobile Radio (DMR). It will help you to become familiar with the complex terminology used by the DMR crowd, purchase and program a DMR radio, and make your first few calls. It also includes sections on how to configure and use a DMR hotspot, using DMR repeaters, and talk groups. The book takes a practical approach, providing the information you need to get started with this exciting digital voice technology. Before you know it, you will be able to talk with amateur radio operators all over the world.
The Parrot TG channel (TG9990) allows you to talk to yourself to verify connectivity and strength with a hotspot/repeater, and every TG that we connect to, we MUST disconnect-from using the SKY TG Disc channel (TG4000).
Tom N8TJ:
Novice 1977 as WD8NPM.
Currently most active on: DMR 3126 Brandmeister, 80m, 40m 20m CW.
Other interests: motorcycles and northern MI.
tom@dmrtechnet.net
Stan WB8QJZ:
I was licensed as a Novice in 1973 as WN8QJZ. I upgraded to Technician C and then to Amateur General Class. Primary interests include portable HF QRP operation and VHF/UHF experimentation including Slow Scan Television reception from the International Space Station . I hold a Commercial General Radio Telephone License. I retired from Michigan Technological University as a Senior Telecommunications Engineer and was the operator and chief engineer for the university’s Ku Band Satellite Earth Station. stan@dmrtechnet.net
Steve KC8WXM:
Was in the U.S. Army 2nd of the 4th Cav. Crew chief for OH-58C Helicopters. Was sent to Saudi/Iraq during Desert Shield, Desert Storm.
Hobbies: Camping, Hiking, Hapkido, Amateur Radio.
Commander of American Legion Post 194 in Petoskey.
steve@dmrtechnet.net
Dana KC0MYP:
In 1977, I passed the FCC 3rd Class license with broadcast endorsement to work at WVIC 94.9-FM/730-AM. After graduating from Michigan State University, I moved to Colorado and worked at Radio Shack for 19 years. In 2002 I earned my Technician class license and upgraded to General in April, 2022. Technology is great–when it works! Currently using three Anytone 878 handhelds and two Anytone 578 mobile radios with BT01 bluetooth mics. I’m most active on Brandmeister DMR Talk Group 3126 Statewide Michigan. dana@dmrtechnet.net