D-Star Information

One of the reasons I enjoy Amateur Radio is being able to talk with people in different parts of the world. At the moment I'm living in an apartment where I'm not able to put up a permanent antenna, and I don't really like the idea of setting up a temporary antenna every time I want to work HF, so for the most part my radio activities are limited to local repeaters, where I'm talking to the same set of people all the time. Not that I don't enjoy talking with the locals, but it's also nice to talk with new people as well.

D-Star

D-Star is a system which uses digital signals to carry voice and data signals over the air. It uses special digital radios which connect to digital repeaters, most of which are connected to a world-wide network of repeaters. D-Star users are able to send commands to their local repeater which cause it to connect to other repeaters around the world. While connected, any transmissions into one of the connected repeaters are heard on the RF output of BOTH repeaters, making it possible to connect your local repeater to some other repeater, and hold a conversation with somebody who may be literally on the other side of the planet.

There are also computer systems called "reflectors" which are connected to the network, and allow multiple repeaters to connect together at the same time, passing audio signals between all of the connected repeaters. Reflectors have made it possible for me, in Florida, to hold a single conversation with people from Texas, Ohio, Scotland, and two different provinces in Australia, at the same time, while driving to work in the morning.

DV Dongle

There is a device called the DV Dongle which allows a computer to connect to the same network used by repeaters and reflectors around the world, and talk to other D-Star users without using a radio at all. This make it possible for people who may not live near a D-Star repeater to still participate in D-Star and talk to others around the world.

The dongle actually contains the "vocoder" chip which translates between a digital audio stream, and a stream of numbers suitable for transmission over the air, or over the internet. This chip is currently the only legal way to do this translation, since the ABME algorithm is patented and the owners don't want to allow anybody to develop their own implementation of it.

I have two problems with this- one with the owners of the algorithm, for not allowing others to develop their own implementations, even under "non-commercial only" terms, and one with the JAL, who developed the D-Star protocol, for choosing an encumbered algorithm to begin with. However, what's done is done, and until somebody comes up with an alternative, we are unfortunately stuck with it.

Robin Cutshaw, AA4RC, who designed the dongle and sells them through amateur radio dealers (such as Amateur Electronic Supply) makes a free Java program called DVTool which allows you to connect to a repeater or reflector, and talk with other people, without using a radio.

Because the program is written in Java, it can be executed on any system with a Java runtime. However, Java doesn't have universal support for sound input, and requires an OS-specific module to handle the sound coming from a microphone. For this reason, it can only be run under Linux, Mac OS X, or Windows.

dvwatcher

I normally use DVTool on Mac OS X, although I have also used it on a Linux netbook as well. Robin's directions for the Mac tell you to just double-click on the DVTool.jar file, and that does work. However, you can also run it from a command line, like so:

$ java -jar DVTool.jar

When you do this, it prints diagnostic information to the terminal session where you ran the command. Part of the information it writes, at the beginning of each incoming transmission, is the call sign sent by the radio which is transmitting (every packet sent by a D-Star radio has the sender's call sign embedded in the header.)

I have written a program which works as a "wrapper" around the Java tool. It runs the program, reads the diagnostic output, and prints it to the terminal window (so it looks just like running the program directly.) However, when it sees the line which identifies the transmitting call sign, it uses QRZ.com to look up the name and address associated with that call sign, and prints that information to the terminal window as well. I think it's rather cool to see the person's name and location before they even start speaking.

When the program looks up a call sign on QRZ, it remembers the data in memory, so it doesn't overload QRZ's servers with requests. It also writes that information to a text file on your system, and when it starts it reads that text file back into memory, so in theory it should never have to look up anybody's call sign more than once.

This is a sample of what the program looks like when it's running. This was taken during the Ozark Mountain D-Star Net on Reflector 1C, on 2009-10-04. The timestamps are local time on the computer itself, which in this case was EDT. (Pardon the background image, I use semi-transparent terminal windows and the Mac OS X screen capture widget captured the background along with it.)

If you are interested in playing around with it, here's the most recent version of the script. Enjoy.