DMR explained with a few words

When I first started with DMR my head started spinning and my consumption of pain killers against head-pain raised dramatically. After a while – understanding the concept – I can say that my analogue Yaesu FT857 is more challenging in terms of settings, than my Anytone DMR radios. Well I am deep into Computers since 1980 which is an advantage for sure. But if you are familiar with Excel (or Ron’s CSV Editor which I prefer due to simplicity), you are nearly there.

DMR is not complicated, it is complex. The other problem you will find is that many information’s in the internet is either wrong, outdated, not very clear or goes too deep into details which are not important for the programming of a radio by the Codeplug (CP) -Software. Basically the whole thing consists of a channel list (analog and digital frequencies named by repeater or the use of it), Zones where you group your frequencies logically (i.e. by country or region), a Talkgroup-list of Talkgroups (TG) you are interested in (World, local, regional, country, state, county, language or specific use like emergency comm.)

You personally need an CCS7 Identifier, a seven digit number which represents you in the DMR (and DStar) network. For Europe and Africa, you can register here. North America, South America, Asia and Oceania must register here. In both cases you have to upload a scan of your License.

DMR user details are available in a CCS7 Database which is ready for download in the internet. Downloaded and imported to the radio, you will see each station with additional information like Call-Sign, Name, City, State, Country.

Further more you have to deal with two Timeslots (TS) named TS1 and TS2 as on one frequency two QSO’s simultaneously can be held, a color code which has to be the same in your frequency list as the correspondign repeater you want to use.

Finally you will find static talkgroups and dynamic talkgroups associated to TS1 or TS2. Which talkgroups are associated to which Timeslot you can find out on the website of your repeater or at the Brandmeister / DMRplus pages of the desired country. The difference is that a static TG is always there, if you want to join a TG which is not static (=dynamic), you choose the talkgroup of your liking in the radio, select it, press PTT and you are subscribed (dynamically) to it with an inactivity timeout of 6-10 min. if you do not have a qso, otherwise you have to press the PTT again. Both kind of TG’s can be on any TS.

 

Was it that hard ?

 

More useful information can be found on the useful links page

 

Time Slot’s and Color Codes…what the hell..?

A timeslot is relatively easy to explain. It divides the digital transmission on the frequency in two channels, named TS1 and TS2. Analog communication can only do one communication on a channel at a time. In DMR two conversations can happen at the same time as the digital packets need less “space” (see graphic below). Depending on the setup of your repeater you will have i.e. static TG’s in TS1 and dynamic TG’s in TS2. Which are static and which are dynamic depends on the sysop and recommendation of i.e. the Brandmeister community. If you want to use a specific TG, simply select the TS2, the TG you want and press PTT for a short time. Depending on the time-out value the repeater sysop has set, you are now in this TG dynamically and without any activity of you (i.e. a QSO), this dynamic TG will be removed after 6-10 mins.

Same with color code. The color code you have set for a digital repeater in the Channels List of your codeplug must correspond with the color code this repeater uses. Most repeaters use color code (CC) 1.You will find the CC’s typically in the repeater lists in the internet for your region, state or country. Here is a worldwide repeater list as an example I have created, which covers all Brandmeister repeaters worldwide which I could find. Due to inconsistencies in the database I dumped the records which made no sense, therefor I am pretty sure it is not complete, but it is a start for you. Keep in mind that if a repeater works on multiple frequencies, it can not have the same name for both frequencies, you have to modify such an entry in your codeplug channel list or in the channels.csv file if you are importing from there.

In the above graphic the 12.5 kHz Bandwidth of a channel is subdivided into 2 TS’s. DMR Radio one and three use TS1 and DMR Radio two and four are using TS2 simultaneous on one channel frequency without disturbing each other.