Digital Radio

How it all begun…

On a business trip to Plano, TX., USA, I had the chance to visit a local Ham Radio store and could buy some stuff, which I have to order in the US to be shipped to Germany normally. Being there I also got me an Icom ID51E plus2 handheld and a ZUMspot kit, to have both connected for digital radio, as the propagation at HF is lousy at the moment (2019). I took the whole package, radio, ZUMspot and the programming software for the handheld. Back home here in Germany, when I passed my license-exam, I took the ID-51 and the ZUMspot (based on a raspberry pi zero and a digital radio “hat” plus pi-star image) out and installed it. Actually no problem, as D-Star is relatively easy to set up. Of course the internet and uncounted articles therein were quite helpful.

As the ZUMspot worked pretty well and everyone is talking about DMR and Brandmeister, I thought it would be a good idea to try this too, to make my decision which system I will finally use most. This was the moment the drama started.

In Amazon I ordered a Retevis RT90 DMR mobile radio. Unpacked and spend a week on it. Finally I sent it back, as the radio does not give me the opportunity to use a proper VFO on VHF and UHF, just channel lists to be programmed through the codeplug software for this radio. Speaking about this software, it is really bad and crashes repeatedly. The radio itself, despite a very ugly display, does the DMR Job well. But in total this bought was a fail.

Therefor I snooped around and found that many many people are using the Anytone handhelds D868uv and D878uv respectively. The 878 also offers Bluetooth for PTT and i.e. headset, GPS and APRS. Also in the crystal-ball of Youtube a mobile radio was presented (D578uv) with similar features as the 878uv but more powerful. As of 9/2019 the delivery date for the D578uv was not clear and already shifted from April to August, than to September, I bought the handheld as the D578uv, shall be based on the software of the D878uv which means that the codeplug’s shall work. And another handheld will not harm, right ?

(Update: Got my d578uv plus in October, works like a charm in my shack. Now – as of Jan 2020, I will order another 578 for my car. The Yaesu FT857d will be installed in the trunk of my SUV for Emergency communications on HF)

Once received, I got it up running with a codeplug from the Dutch OM PC5E, who has a ton of information about DMR and Brandmeister on his website which you can find as . Due to the fact that I live in Germany, 30mi (45km) away from the Dutch border and about 100mi (160km) away from the border of Belgium, his Codeplug (CP) covering Belgium, the Netherlands, Germany with Roaming etc. was from heaven sent, to get the radio up in basically no time and to learn. With this CP my learning curve was that steep, that I could program a (my point of view) more versatile one for whole Europe after 3 weeks, planning to write a CP-Generator together with a friend, who is not an OM, but an excellent programmer. 

Codeplug running is one, happy with the radio is another, but now the nifty thing started. Running DMR and D-Star on one ZUMspot drove me nuts. Another thing is  that there are too many “Prophets” which give incorrect information. That basically made me retry and retry over and over again.

Finally what I found out are basic operational things, no one really tells you because of gadget-blindness, what is missing in all explanations about reflectors, repeaters, colour codes, timeslots and talkgroups. It is so damned simple, that it hurts, but makes totally sense:

  • A ZUMspot uses one antenna, for transmit and receive. That means it can either transmit or receive. Simply Simplex !
  • A ZUMspot can only transmit or receive in one DMR timeslot (TS2) per Design. If you have two talkgroups static booked, each talkgroup (if active) blocks the other.
  • A ZUMspot can only transmit or receive one Digital Radio System at one time. If you enable DMR ….AND…. D-Star, they block each other. If one of each transmits or receives, the other one is unusable.

Now, set it up for DMR and D-Star, set static groups for DMR. What you get is….FRUSTRATION !!! This could be read as “A ZUMSPOT IS BAD”, no a ZUMspot is a pretty cool and superb working piece of a mastermind. It is you who tried to do more than this thing can handle (and the prophets did not tell you = even worse they suggested the misuse between the lines).

How a ZUMspot is to be used ? Simple, use it for one system, no static talkgroups in DMR, in Simplex mode (one Frequency for TX/RX). I use it now in the car, with the DMR handheld and I am very happy with it. When I want to change the Talkgoup (TG), I select the TG, press PTT and I am dynamically in this talkgroup, each PTT press in this TG gives me another 10mins of dynamic allocation. Fair enough for a hotspot in the car.

At home I use 2 (!!) dual hat hotspots, one for DMR, on for D-Star. The DMR one can handle two Timeslots (TS) and has one transmit and one receive circuit (That is what Dual hat hotspot means, two independent circuits for TX/RX which can handle 2 TS. Given that I can transmit/receive on TS1 and TS2 which gives me 2 channels each for transmit/receive = 4 channels of communication. 

On the following pages I will explain the installation of the ZUMspot in the car and the two dual hat hotspots at home for the two system. Of course if I would use the two systems also in the car, I would install a second ZUMspot there.


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