brainwagon

The federal government is currently considering the possibility of legislation banning the use of cell phones and texting. I’m mostly okay with that, because, quite frankly, it’s obvious that people aren’t very good at operating a cell phone or texting while driving, a fact which has been reinforced by study after study. But while many […]

Courtesy of hackaday, here’s a link to a list of nifty high altitude balloon projects: High altitude balloons – Hack a Day.

David Rowe is working on a very cool project that should be of interest to hams with an interest in digital communications. He’s creating an open source, low bit rate speech codec. His target is a usable 2400 bps codec that is free from patent issues, and that can be used in situations similar to […]

It looks like the launch of the South African amateur satellite is on track! The launch of SumbandilaSat is on track for 15 September 2009. In an interview with SA AMSAT, Johan Erasmus, SunSpace systems engineer speaking from Baikonur, said that the satellite travelled well and that all system performed to specification during the testing […]

From a thread on qrz.com, here’s a nice list of 1000 utility stations which broadcast on HF. Nifty. HF Reference Material

Just a place holder for a link to an interesting FM receiver that could be used for receiving NOAA polar orbiting satellites. It was an entrance in the Atmel 2004 Design contest. Very neat. Atmel AVR 2004 Design Contest

I haven’t been playing with the LEO sats much lately, but it’s good to hear that the South African amateur satellite SumbandilaSat is nearing launch. It has a 2m/70cm FM transponder, and a voice beacon. I’ll try to get more information as the launch date gets closer. SumbandilaSat launch scheduled for Sept 15

It’s late, so I am not figuring this out, but I seem to be getting quite a bit of ripple in the output of this demodulator. I bet that it is because I don’t know what I am doing. Oh well. More for later, I guess.

I tried to record the pass of the ISS as it came over, but I heard nary a peep (or beep) from it as it went over. Annoyed, I did a quick search, and found that the NOAA 17 satellite was just coming up. I retuned and hand tracked that, yielding the following rather nice […]

I’ve blogged about the experiments of Nyle Steiner before, but just recently got back to his Spark Bang Buzz website again, and found that he’s added a couple of interesting bits. In particular, he shows how to modify a common Cadmium Sulfide Photocell to act like a field effect transistor. The voltage gain provided is […]

IN

So, armed with the SSTV link that I dug out yesterday, and with a couple of hours this morning to tinker, I started working on an SSTV decoder. It’s not much different than the APT and WEFAX decoders I had written before, but they used amplitude modulation of an audio subcarrier, and most (all?) SSTV […]

Don’t you hate it when you remember seeing a webpage but can’t remember exactly how to get there? This one took me a bunch of judicious web searching to finally uncover again. It basically details how you might go about making an SSTV demodulator, some of the details of which I was a bit sketchy […]

The ISS should be operating SSTV on August 3 and 4, using the Robot36 mode. I’ll go ahead and see if I can catch some pictures from space that way. Should work well, after my success with AO-51. SSTV Aug 3 & 4 | ISS Fan Club. Addendum: If you want to test your SSTV […]

Well, it works! Using the information in the paper I linked earlier in the day, I spent some time and managed to code up a Robot36 SSTV encoder. Above, you see the image decoded by Multiscan on my Macbook. Here’s a link to the .wav file: