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 The other problem you will find is that many information’s in the internet is either wrong, outdated, not very clear or goes too deep into details which are not important for the programming of a radio by the Codeplug (CP) -Software.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.

My Digital Radio Setup

How it all begun…

When I was on a business trip in Plano, TX, I visited a local Ham Radio Outlet (HRO) and bought an ICOM ID51E for DStar and a ZUMSpot. Back home in Germany I made it to work within a few days as this was completely different from my analogue experiences in HF/VHF/UHF so far. But the activities here in Germany on DStar were not overwhelming and in a lot of publications DMR was pushed heavily. The ID51E still exists but I am now mostly on DMR-Brandmeister, which I really like.

Due to the fact that the ZUMspot can do both, I ordered an Retevis RT90, but we both did no click into each other. I got it working, but the software was not stable, crashed very often and the radio could only be run via Codeplug, no VFO Operation possible.

As I bought it at Amazon, I could send it back within 30 days, but I was already highly frustrated after 14 days and simply sent it back. I promised myself to do some more researches which radio could suite me best and came across the ANYTONE radios. I had a look at the AT-D868UV and AT-D878UV Plus (with Bluetooth and Bluetooth-PTT) and ordered it at a distributor here in Germany. Received, unboxed, Software installed. WOW !!! THIS IS COMPLEX AND COMPLICATED ! (Actually it isn’t when you have understood the basics, which I will explain in another post)

 

During my researches I came across the website of a Dutch HAM, PC5E who is dedicated to a lot of different DMR radios of many manufacturers. I downloaded his Anytone codeplug for Germany, Belgium and the Netherlands and studied what he had done to get the Anytone UV878UV running. Playing around with it I understood the concept of codeplugs. Not in depth and not using all features of the Anytone, but enough to get it running. Now, 6 month after buying the AT-D878UV I create Codplugs for others, using my blueprints and being the proud owner of one AT-D878UV Pro and two AT-D578UV Pro (one in the car, one in the QTH).

Beside the radio’s I own four hotspot’s. One ZUMSpot, which I do not use anymore, as it was making problems (not investigated on it) when I visited a friend in Canada (12/2019) and I will later take care of it. I use two MMDVM (China-Clone) Dual-Hat Hotspots mounted on two Raspberry Pi 3B, one for DStar, one for DMR and a brandnew SharkHF openSPOT3 for use in the car, hotel or anywhere I do not have a proper repeater or do not know the repeater frequencies. The openSPOT3 is typically connected through a LTE wifi hotspot or my mobile phone in tethering mode.

At home I use the Dual-Hat Hotspot for DMR to have TG91 (world) and TG262 (Germany) on Timeslot 1 and Timeslot 2 in static mode as the German Brandmeister Repeater OM’s only have TG262 static, TG91 is set to dynamic, which means you get kicked out every 6-10 minutes (I personally don’t understand that and think it is a shame not doing TG91 static – it is contrary to the idea of amateur radio). With this fact in mind I use my portable radio to monitor TG91 via the hotspot and the D-578UV in the shack to monitor TG262. Both, TG262 (TS1) and TG91 (TS2) are set to static on my hotspot(s).

The other Dual-Hat hotspot at home is dedicated to DStar. Both Dual-Hat Hotspots run the pi-star software.

Here at home I use a DIAMOND X30 about 10m (30ft.) over the ground and  under the roof for the AT-D578UV Pro and a special construction at the car for a Diamond NR-770H which can be flipped to a horizontal position which is useful for parking garages. In the car I use the Bluetooth PTT switch, mounted to the gear-stick and a typical BT-Headphone for a mobile phone. This does the job more than well. Same for the handheld AT-D878UV , BT-PTT-Switch attached like a wrist watch (with a wrist watch band) to my right arm with the same BT-headset from the car. In the QTH I use a callcenter style BT-Headset with the PTT-Switch on the desk or in the pocket.

BT-PTT Switch with a wrist watch band  BT-PTT Switch as delivered

 

+ QTH use: AT-D578UV Pro with a callcenter like BT headset and the BT PTT-Key either in the pocket or on the desk
+ Portable use: AT-D878UV Pro with a BT headset for mobile phones and the BT PTT-Key with a wrist watch band
+ Mobile use: AT-D578UV Pro with the same BT-headset for mobile phones, BT PTT-Key mounted to the gear-stick

For the handheld I use (depending where I am) the DIAMOND SRH805S which is only 3.5 cm or 1.5″ long (!!) which works very well, the manufacturers antenna and a DIAMOND SRJ77CA Antenna, about 40.5 cm / 15.9″ long. With the SRJ Antenna I could easily reach repeaters in Canada 30km / 19mi away from the livingroom of my friends house.