More fun on HO-68! During a low elevation pass, Mike DK3WN and Henk, PA3GUO made the very first SSTV contact via HO68 – linear transponder. Images were transmitted between the two radio stations in Germany and The Netherlands. Signals were transmitted to HO-68, which was 1200km above earth and about 8000km distant from the radio [...]
Archive for month: December, 2009
I keep thinking that I should build one of these, but have never gotten around to it. Bookmarking this interesting link for future reference: Build Your Own 3D Scanner: Optical Triangulation for Beginners. Build Your Own 3D Scanner: Course Notes View more documents from Douglas Lanman.
I don’t really have the hardware to effectively transmit to satellites in linear transponder mode. To really make it straightforward, you probably would like to have a computer to handle the Doppler tracking and antenna pointing, and a full duplex SSB transmitter (or a pair of ordinary ones). That’s more than I am willing to [...]
Well, I went ahead and built the Gilbert cell mixer from the Elmer 101 pages in LTSpice. I’m not sure I understand the biasing that it uses, but it does seem to work. I’ll think about it more later.
This morning I got another chance at HO-68, the newest Chinese amateur satellite that was operating in FM mode. I wasn’t sure what the problem was: I had the PL tone setup right and the signals seemed strong enough. On this pass, I fought to try to find a slot to transmit, and finally at [...]
I was surfing around the web today looking for an LTSpice model for the NE602, and came across the Elmer 101 FAQ, which is basically an explanatory supplement for the Small Wonder Labs SW40. I haven’t read this carefully yet, but it looks awesome, including much discussion of how the various circuits were designed and [...]
I like trebuchets. Former Pixarian and RenderMan engineer Dan apparently located some plans for building small trebuchets from the Hila Science Camp: The Hila Trebuchet. And here’s a short YouTube video showing him test firing four of them. Cool! Bonus video (unrelated to the above): Dan also posted a link to this video, showing video [...]
As I was chatting on the QRP Echolink conference tonight, the subject of code practice oscillators came up. I think it was Bob, AD7BP who first mentioned the NT7S Code Practice Oscillator which I hadn’t seen before, but seemed like a very simple and easy to assemble circuit. We also discussed the fact that [...]
I’ve mentioned before that I’m a pretty big fan of Sherlock Holmes. Every couple of years, I dust off my copy of his stories and read them, or load them as audio books onto my iPhone and listen to them all over again. I could go on and on, but let’s just say “I’m a [...]
Okay, I’ll admit it: I like cooking, and I’ve begun to read a bit upon the subject of so-called “molecular gastronomy”. I was also watching Iron Chef America, and saw (not for the first time) a chef use the “sous vide” technique of cooking: where a protein is sealed in a vacuum bag and placed [...]
Yep, it’s Christmas again, and I’m such a geek, I can imagine all sorts of things that link it back to radio stuff. If you follow the link below, you’ll find that one of the first (if not the first) audio broadcasts was made on Christmas Eve, 1906, by Canadian scientist Reginald Fessenden. These first [...]
The new Chinese amateur radio satellite, formerly XW-1, now designated HOPE-1 or HO-68, made a pass with its FM transponder active around 10:00AM local time here. I was unable to get a signal through, no doubt in small part to some incompetence on my part, but also judging by the amount of doubling and piling [...]
Yes, Christmas is upon us again, and this year we are treated to a movie release about a character near and dear to my own heart: Sherlock Holmes. While I am rather fond of Robert Downey Jr., Jude Law, and even Rachel McAdams, I can’t help but think that this reinterpretation of the classic stories [...]
Checker expert Jim Loy has a number of quizzes on his website, including the following one that I found as part of my earlier post on the Double Cross opening: Quiz #10 – Double Cross. Here are the moves that milhouse chose with a hard time limit of 30 seconds per move, along with the [...]
I noticed that Martin Fierz released a new version of his Checkerboard program, so I thought I’d set it sparring against my own program, milhouse. The Cake engine it ships with walks all over my program, but it managed this win against Simple Checkers. [Event ""] [Date ""] [Black "Milhouse"] [White "Simple Checkers"] [Result "1-0"] [...]