Diving into D-STAR – 1

By Toshen, KEØFHS (Updated May 2018, CC BY-SA)

D-STAR logo
The D-STAR logo is a
registered trademark of Icom

Why bother?

When I first dove into D-STAR, I knew nearly nothing about digital voice and quickly found myself drowning in a big bowl of bewilderingly murky information soup. If it's so bewildering, why even bother?

I'll jump a bit ahead here and share one tidbit: at one point early in my exploration of D-STAR, I linked to a reflector and heard a guy in San Diego, California chatting with a chap in Yorkshire, England. That was the moment I became hooked. Just think of it: worldwide communication with a Technician class license, a bit of effort and learning, and some fairly simple equipment!

Of course, the real goal isn't to just listen but to actually chat with people. This is the story of how I got there.

Today's amateur radio experimenter is as likely to use a keyboard as a soldering iron for experiments, and as a digital enthusiast, I can only cheer and encourage you to get involved and have some fun.

– Don Rotolo, N21RZ, Vocoding: Creating Digital Voice⇗, CQ Amateur Radio

1) What is digital voice?

The simple answer is that digital voice (DV) uses digital rather than analog audio. But what does that really mean? For me, it was all quite murky when I first started looking into it, and it took me quite a bit of exploring and head scratching to begin figuring it out.

This section provides an introduction to the basics of digital voice and hotspots, including links to some helpful websites, articles, and other content, in case you want to dive in more deeply. You also can find all the links together on the Notes page at the end of this article: Links to helpful resources⇗.

1a) Alphabet soup

As I began flailing around in the digital voice murkiness, one of the first things I figured out is that it's actually a bit like a big bowl of alphabet soup … it's absolutely crazy how many acronyms are floating around!

Bowl of alphabet soup with digital voice acronyms floating in it
Alphabetsoupese by Toshen, KE0FHS
Derived from an original photo⇗
by Leo Reynolds⇗. Some rights reserved⇗.

Even worse, sometimes the acronyms are spelled out differently, which makes searching for information more challenging. Other times, it isn't easy to determine what an acronym actually stands for, for example, I've seen DCS defined as Digital Call Server, Digital Communication Systems, and Digital Call Service, and I'm still unsure which is correct. Perhaps it stands for Darn Confusing Stuff? ! 

Since there's no avoiding this craziness, you just have to accept it as part of the price of admission. And don't worry, by the end of this article, you'll be speaking "Alphabetsoupese" as fluently as is possible!

1b) Multiple systems

The next thing I understood is that D-STAR is just one of several competing digital voice systems being developed, though it's one of the earliest, and the first to be developed specifically for amateur radio use.

The logos of D-STAR, DMR, System Fusion, NXDN, P25, and FreeDV

The Japan Amateur Radio League began development work on the Digital Smart Technologies for Amateur Radio (D-STAR) standard in the late 1990s and published it in 2001. It started to gain traction in the U.S. around 2006.

The D-STAR standard has been adopted primarily by two first-tier amateur radio equipment makers, first by Icom, the D-STAR trailblazer, and more recently by Kenwood. By now, it's being used by tens of thousands of amateur radio enthusiasts worldwide.

It's also an open standard (with the exception of the vocoder chip, which is discussed in the following note: Alphabetsoupese – example 1), so it's being used for lots of experimentation, and that means there's a bunch of interesting homebrew and small manufacturer hardware and software available.

Other digital voice systems being developed or adapted for use by hams:

1c) Transceivers, repeaters, and reflectors (oh my)

Just as you can use analog transceivers in FM mode, you can use digital voice-capable transceivers in DV mode to talk directly from radio to radio simplex 1 or via a repeater (as long as it's a digital voice repeater).

Diagram of DV HTs connecting via simplex and via a DV repeater
[1] The U.S. DV simplex frequencies are 145.670 (2 M) and 446.225 (70 cm).

It gets even more interesting when digital voice repeaters are bridged together, enabling groups of two or more people, even far flung, to participate in something that's like a conference call.

Diagram of DV HTs connecting via DV repeaters to a reflector

Linking together in this way to participate in a call or net is a big part of what playing around in the worldwide D-STAR playground is all about.

In the D-STAR world, this technology is called "Reflectors" (transmissions are reflected to all repeaters linked to the reflector), while DMR calls it "Talkgroups" and System Fusion calls it "Rooms." D-STAR also has a new open routing system called QuadNet Smart Groups that bridges users together in a similar fashion.

Here, too, there are multiple systems being developed and used simultaneously. Within just the D-STAR world, there are four main reflector systems as well as the open routing system:

  1. REF – The DPLUS reflector system, a closed proprietary system developed by Robin Cutshaw, AA4RC, is the first generation of D-STAR reflectors and still much in use, especially in English-speaking countries. An example is REF001⇗ in London, referred to as D-STAR's "Mega Reflector." REF directory⇗.
  2. XRF – The Dextra X-Reflector system, originally created by Scott Lawson, KI4KLF, is the second generation of D-STAR reflectors and is open source. An example is XRF720⇗, which links several Colorado statewide D-STAR repeaters. XRF directory⇗.
  3. DCS – The Digital Call Server reflector system, a newer closed system developed by Torsten Schultze, DG1HT. DCS directory⇗.
  4. XLX – The XLX reflector system, being developed by Jean-Luc Boevange, LX3JL, and Luc Engelmann, LX1IQ, is an open system and the newest, which they describe⇗ as "the first and only multiprotocol Reflector system until now and supports all standard D-STAR protocols like DCS, Dextra and DPlus fully transparent."
  5. Smart Groups – The QuadNet open style routing system, is based on an idea called STARnet by John Hays, K7VE, and first implemented by Jonathan Naylor, G4KLX, as StarNetServer. Tom, N7TAE, Colby, W1BSB, and the QuadNet⇗ team is now taking this idea to the next level with their new Smart Group Server: "A routing group is kind of like a reflector, but it is actually more like a repeater without the RF transceiver. A routing group can have many individual users 'subscribed' to it. Anyone subscribed to a group will hear all traffic on the Group."

To learn more:

Same difference

While there are some differences between the three main digital voice systems being used by hams—D-STAR, DMR, and System Fusion—they share many similarities. Given their shared similarities, perhaps the most surprising thing is that they don't talk to each other. They are like three side-by-side playgrounds, all with similar swing sets and slides, but with arbitrary fences separating them.

For an update about progress being made breaking down the fences between the digital playgrounds, see: Constellations: a big leap for digital voice⇗.

If you want to learn more about the comparisons of the digital voice systems:

1d) Hotspots (Personal access points)

This is where it gets really exciting and fun, at least for me. One more piece of the puzzle is figuring out how to get onto the digital system when you're not within radio range of a digital voice repeater.

Fortunately, there are innovative hams creating hotspots and software that enable a ham with internet connectivity to link directly to reflectors or DV repeaters, bypassing the need to transmit from the radio to a DV repeater first. Basically, these hotspots act as your own personal repeater and gateway.

Diagram of DV HTs connecting via personal access points to a reflector and a DV repeater

There's another nice aspect of the hotspots: since you link directly to a reflector via a hotspot, you don't tie up a DV repeater the way you would if you use your radio to send a command to the repeater to link it via its gateway to a reflector for your personal call on that reflector. This may make a hotspot interesting even for someone who lives within range of a DV repeater.

1e) A Wild West frontier of amateur radio!

Digital voice, especially in the area of hotspots, is like a Wild West frontier of amateur radio. There's lots of experimentation going on, which means both excitingly rapid progress as well as some abandoned dead-end branches of exploration.

One of the challenges of trying to learn all of this, especially for someone like me who isn't a SuperNERD, is that while there is some quite good information available online scattered around in various places, there's also some outdated and incomplete information out there. Because of this, I found it unfortunately much too easy to take some wrong turns along the way.

In this article, I share mostly the right turns I've taken, but will warn about a few potential wrong turns, like …

Be aware of the date!

Be aware of the date (or lack of date) of any material about digital voice radio that you come across, including this article (see the "last updated" date at the top). In an area that's changing this rapidly, information can be quite time sensitive.

If the material is much more than a year or two old, it may contain information that is wrong or at least partially outdated. Even if it's still technically correct, it may have been superseded by more current information posted elsewhere.

Example: There is a tip that is still live online today (as of Mar 2018) in an undated D-STAR article ranked highly in search results—which I mistakenly presumed meant it was relatively current—claiming that you can access X-Reflectors with the DVAP/DV Dongle devices running the DVAPTool/DVTool software by making changes to the "hosts" file.3

I didn't even know what a hosts file is when I first came across that tip. After figuring out what it is and how to change it, I spent a lot of frustrating time trying to make the workaround actually work before learning via another website that an update made to the DVAPTool and DVTool software in early 2012 intentionally blocks that workaround.4 That tip is more than five years out of date!

Fortunately, I was able to use what I learned about the hosts file for other tasks, so not all the time I spent on this was wasted.

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