Home / D-STAR, C4FM and DMR
On Polish repeaters, alongside FM, three mutually incompatible digital systems coexist. Each was created elsewhere and for a different reason; all three process voice with the same codec, yet a radio for one won’t talk to another. Below: where they came from, what really sets them apart, how many there are in Poland, and which one to start with.
If a single standard had been created, this page wouldn’t exist. Three appeared because each had a different parent and a different goal.
Written from scratch for radio amateurs by the Japanese association JARL, with a network in mind where the address is the callsign. The oldest, the most “amateur” in spirit — and the only one without commercial roots.
Yaesu’s answer to D-STAR: also for amateurs, but entirely proprietary. Built for maximum simplicity of entry — you buy a radio, enter your callsign and get on the air. No registration.
A professional standard, created for firms, security and services. It made its way into amateur radio through the back door when Chinese radios dropped in price to a hundred-odd PLN — and today it is the most widespread in SP.
The key differences on one screen. The “repeaters in SP” row comes from my database — multi‑mode machines are counted in every system they support.
| D-STAR | C4FM / Fusion | DMR | |
|---|---|---|---|
| Creator, year | JARL, 2001 | Yaesu, 2013 | ETSI, 2005 |
| Modulation | GMSK | 4FSK (C4FM) | 4FSK |
| Bit rate | 4800 bit/s | 9600 bit/s | 9600 bit/s |
| Voice codec | AMBE, 2400 bit/s | AMBE+2 | AMBE+2 |
| Channel | 12.5 kHz | 12.5 kHz | 12.5 kHz with TDMA |
| Calls per channel | 1 | 1 | 2 — two time slots |
| Addressing | callsign | callsign entered in the radio | ID number + talkgroup |
| Registration | yes — one‑off at the gateway | no | yes — DMR ID number |
| Network backbone | ircDDB + REF/XRF/DCS/XLX reflectors | WIRES-X (Yaesu) and community-run YSF and FCS | BrandMeister, DMR+, FreeDMR, TGIF |
| Data alongside voice | 1200 bit/s all the time — GPS, text, description | in DN mode, half the stream is data | short messages and GPS, depending on the network |
| Hardware | Icom, Kenwood | Yaesu | a dozen-plus manufacturers, from Motorola to Anytone |
| Cost of entry | high | medium | lowest |
| Repeaters in SP | 62 | 74 | 112 |
If all three use the same kind of codec, why don’t the radios talk to each other? Because a codec is only a way of compressing voice. What differs is everything around it: modulation, framing, addressing and the network protocol. It’s a bit like sending the same MP3 file once by post, once by fax, and once by carrier pigeon.
D-STAR’s biggest advantage isn’t visible in a table: callsign routing. You enter your friend’s callsign and the network itself finds which gateway they last transmitted through. You don’t need to know where they are or which group they joined. Data rides alongside the voice, so the display shows who’s transmitting and from where before they finish the first sentence. The price for that: a one-off registration and the most expensive gear of the three.
Fusion is unbeatable at the start: zero paperwork. You enter your callsign in the menu and you’re on the network. The radio switches itself between digital and analogue FM (the AMS function), so the same channel serves both worlds. In VW mode the entire bitrate goes to voice — and you can hear it straight away, as it sounds the best of the three. The downside: one company, one manufacturer and one ecosystem.
DMR wins on numbers: the most repeaters in Poland, the cheapest radios, the largest networks. You pay for it with a learning curve: you need to obtain an ID number, and you don’t program radios from the keypad — you load a ready-made codeplug from a computer, a file with channels, talkgroups and colour codes. In return it’s the only one that fits two independent conversations into one channel by splitting time into two slots.
Figures from the repeater database — 438 entries, up to date. The total is higher than the number of repeaters, because many machines support several systems at once.
You can hear the difference exactly where the table points. D-STAR gives the codec 2400 bit/s and sounds the most “telephone-like”. C4FM and DMR use the newer AMBE+2, and Fusion in VW mode can give the full 9600 bit/s to voice — the best-sounding option of the three, at the cost of no room for data.
A common feature of all three: no noise. The signal is crystal clear right up to the moment when error correction cannot keep up — and then, in a single step, it breaks up into metallic “R2D2” and goes silent. On FM you can hear the other station moving away; on digital it just disappears. But up to that threshold it is clean, where FM would have been noisy long before.
AMBE and AMBE+2 are the closed, proprietary, patented technology of the American company DVSI. In practice that means every amateur digital radio contains a chunk of licensed hardware or software that nobody outside can inspect or legally re-implement. For a community that’s been building its own transmitters for a hundred years, that’s a bit of a sore point — and that’s exactly why M17 was created: a fully open amateur standard with the free Codec2 codec. There isn’t much hardware yet, but popular hotspots support it.
A radio for one standard won’t receive another, but the networks can interconnect on the internet side.
The honest answer is: the one that works in your area. Check first what you have within range — only then buy a radio.
Go for C4FM. No registration, no codeplug — enter your callsign in the menu and you’re on the air. The radio will also handle plain FM on the same channel.
Go for DMR. Lowest price point and the densest network in Poland. Expect an evening spent programming a codeplug — or ask someone at the club for a ready-made one.
Go for D-STAR. Callsign routing, GPS position in the background of every transmission and the most “radio-like” approach of the three. You’ll pay the most and go through registration once.
Then the standard barely matters — buy a hotspot that supports all three, and choose the radio for ergonomics rather than the network.
I’ve written a separate guide from scratch: callsign registration, the four fields in the radio, DR mode, reflectors, a hotspot and your first QSO — all in Polish and step by step.
