Monday, January 25, 2010
A Communications Tool For D-STAR
I have been watching the D-Star protocol since it came on the scene and while it piqued my curiosity the data rates didn't impress me until you got up to 23 cm band. Even there you are only looking at 128kbs which is about the equivalent of an ISDN line and since the radios don't work full duplex you can cut that in half under the best of circumstances. When you combine that with the fact that even though D-Star was developed by the Japan Amateur Radio League currently only Icom is manufacturing equipment for use in the ham bands and that is another strike against it. I think if Kenwood or Yeasu would come on board with similar radios that would do a good deal to promote D-Star's use.
I got into packet radio about the time that dial up speeds started to double every few years and all of the sudden 1200 baud half duplex was looking pretty slow. Granted there was no WiFi at that time so it still held some magic in that I could throw together a rig, TNC, antenna, power supply and terminal and be communicating with other packet stations far beyond my simplex reach through digipeaters. Checking mail on the local BBS system and chatting keyboard to keyboard once in a while. Still I had been bitten by the Internet and its 56 kbs dial up connections. Man was that fast! Did you know that when the original ARPA Net, the forerunner of the Internet, was born it had a backbone that was 56K? Anyway I digress.
Now here we are all these years latter and amateur radio is still languishing in the 1200 baud world of packet and APRS with a smattering of 9600 baud activity here and there if you are lucky. Now I realize that many of the speed disadvantages we experience are due to bandwidth limitation on the most common used bands like VHF and UHF. HF is an entirely other matter all on its own.
The resurgence of public service side of ham radio has sparked a new interest in being able to transmit not only voice but data from point to point under less than ideal conditions. I am still somewhat disappointed in the fact that we have not established a wide area mesh network using protocols like 802.11N on the frequencies were we can run wider bandwidths and higher data rates. We however do have to live in the real world. So when D-Star came along providing the transmission of both voice and data on the same channel all in digital format that looked like an advancement to me. I was also disappointed in that fact that it uses a proprietary codex for the analog to digital conversion of the voice as I much prefer open standards that let everyone compete on a level playing field. I guess the problem is getting everyone to agree on what that "standard" is going to be.
So while surfing the other day I ran across D-Rats, a program that greatly enhances the capabilities of a D-Star equipped radio. It allows instant messaging style chat as well as file transfer from one radio to another including binary files with compression. There are other features that I won't go into here if you are interested I will provide a link to the D-Rats home page where you can get additional information. One of the best things about D-Rats is that it is multi platform and open source. So you are free to contribute to the project if you choose and it will run on Windows, Mac and Linux.
I have been a strong advocate for some time now that any software promoted for use in emergency communications should be free and open source so that a robust developers community could grow around it and improve it to the best possible level that it can achieve. I have expressed this opinion in person at meetings and in written form to the ARRL and other organizations. Perhaps one day we will have a data network that will rival the 3G networks currently in place for the cell industry but until that time comes I hope to see hams moving into the digital wireless world and learning more about networking and creating new technology that will enhance both the hobby and the communications industry in general.
Labels: D-Star digital voice D-Rats protocol bandwidth networks
