Last weekend I went on a two-night backpacking trip in the Sipsey Wilderness Area with ten scouts and a couple of other adults. We had a great time, with two nights with sub-freezing temps. For me this was a milestone, the first backpacking I’ve done in years since knee and shoulder surgeries.
I had forgotten a couple of things - The first was just how many stars (and other objects) you can see from earth when you are far away from light pollution. Adding to the clarity we had clear, cold air overhead from the front that had just passed through. The second thing I hadn’t thought about in a while was how much lower the rf noise floor is away from my house and urban areas. I had my Elecraft KX-1 along, and threw an antenna up into a tree. I ended up not trying to make any contacts because a) It hurt to take my hands out of my gloves and b) there was a CW contest on, and I was not very confident that I could copy well enough. So I spent several hours just practicing copying CW, and made some real improvements. I was amazed by what I could hear! Just like realizing that there are so many stars you normally can’t see, there were an incredible number of signals out there.
I need to get out more often.
On November 6th I’ll be helping Dave Freese, W1HKJ make a presentation about fldigi to the Huntsville Amateur Radio Club. Fldigi is an amazing open-source cross platform application for communicating using sound card digital modes on amateur radio.
Dave is really knowledgeable about the encoding and error correction used for the various modes, and I learned a lot by helping him with a similar presentation at the Huntsville Hamfest this year. Our demo was cross-platform between Windows and Ubuntu Linux.
There are some really interesting uses being made of fldigi and some companion applications - sending digital files error-free by amateur radio. This is useful for emergency communications in post-disaster situations, when information must be accurately transmitted. Some of these applications do not use point-to-point connections, and therefore allow a file to be received by multiple stations at once. That way, if any station fails to receive the file correctly, they can get a “fill” from any other station who did get it.
It’s possible to perform these file transfers simply by holding the microphone on an FM radio near the computer speaker, and to receive them with a computer microphone near the receiver!
This should be a worthwhile presentation for people with any level of interest or experience in digital sound card modes. For more information see Dave’s excellent web site. Don’t miss his sights and sounds of digital modes page, especially if you’ve been listening to the sounds on the ham bands and wondering what modes they are.
The presentation will be November 6th at 7:30 at the American Red Cross chapter house, 1101 Washington street, Huntsville, AL. This is the regular weekly meeting place and time of the Huntsville Amateur Radio Club.
I just noticed a couple of new Linux amateur radio projects. The first is a D-Star compatible repeater - More info Here and the project page is here . I see no mention of source code or a license for the repeater code, but it is apparently based on Centos. The second project is an APCO-25 decoder, and is clearly available under the GPL.
After months of suffering an intermittent HF noise problem, tonight I noticed it had settled into a cycle of 01:05 minutes off, 00:45 on. Hmmm. Streetlight? A walk around the neighborhood and I found it. Tomorrow, a call to Hsv Utilities.
Dave Freese, W1HKJ will be presenting a forum at the Huntsville Hamfest titled “Emergency Communications using HF Digital Modes”. Dave and a core group of contributors have been working for the last few years on a suite of open source applications for amateur radio. The fldigi application is the flagship of these.
Fldigi is a digital modem application which generates and decodes a number of digital modes using the sound hardware in your computer. Amateur radio using digital modes has been growing in popularity, and with good reason. These modes offer a variety of tradeoffs between rf bandwidth, data bitrate, error correction, and noise immunity.
These modes are all sent and received using audio frequencies that fall in the normal voice range used in amateur radio, about 300-3000 Hz. Some modes use very little bandwith, as low as 31Hz, allowing many contacts to take place within a frequency range that would be occupied by one voice contact. These modes are most commonly used with a text interface that resembles internet chat, but are also suitable for inclusion in a higher layer of protocol which allows further error correction, block sending, and retries. When used with a ‘stack’ like this, it is possible to send binary files over amateur radio error-free. This is useful for emergency communications. An example is to be able to send a spreadsheet listing items needed at a shelter, instead of reading and copying every line in the document by voice. The low speeds of these modes limit the usefulness to relatively small files, but a lot of information can be passed in small text files.
Fldigi runs on Linux, Free BSD, Windows XP, W2K, Vista, and OS X. At the hamfest, Dave will be demonstrating using windows and a Linux platform, and I will be helping him demo with my Ubuntu system.
The forum is at the Huntsville Hamfest from 14:00-16:00 on Saturday August 15th, in Salon 10. For more information about these apps, see Dave’s site
I’m presenting a forum at the Huntsville Hamfest about the ARRL Teachers Institute on Wireless Technology, and specifically about the amateur radio program under way at Bob Jones High School in Madison, AL. The forum is in Salon 5 at 10:00 Saturday morning
Two years ago, I started talking with teachers at BJHS about an amateur radio program. Over this summer break, eight teachers from the Madison school system attended the ARRL Teachers Institute on Wireless Technology. We are in the process of forming the amateur radio club at BJHS, and we have a lot of momentum going.
If you are interested in bringing amateur radio to a school near you, I think there are four key things that you need to do. The first is to have a contact within the school who understands the potential of the program and will support it within the school system. The second is to have the support of your local amateur radio club. Third, read the ARRL material about the program and make contact with Mark Spencer at the ARRL. Finally, make contact with individuals who have already championed this program in local schools. I was helped in my efforts by Ed Tyler, KI4GKS, who helped set up a program at Pell City High School.
I’ve committed to write a monthly article for our amateur radio club newsletter on Linux and amateur radio. I’ll be posting them here also. The first one is an introduction to how to run linux from a live CD or to install it.
I’d like to expand this so that I’m writing more often here, and then consolidating those pices for the newsletter, and also take the chance to get more information into the Ubuntu wiki pages for amateur radio.
