I’m still working on “the code”, but this weekend is the CQ Sweep Stakes, and all the bands are alive with Morse code contacts. I recorded about 10 seconds of audio, and then converted it into a spectrogram so you could see the dozen or more simultaneous signals that are all present in a small bit of the 40m band. It’s chaos!
Try clicking on the image above for a closer look.
While waiting for my K1EL keyer kit to show up, I was twiddling my thumbs, and remembered that I had an Arduino microcontroller board sitting around. I originally bought it for an aborted robotics project, but haven’t touched it in months. I redownloaded the development environment, and a few minutes later, I had it happily blinking a Morse beacon message on pin 13, as well as typing the beacon message repeatedly out on its serial port.
It’s a trivial program, and the Arduino is capable of much, much more. When I get home, I’ll solder together a simple keying circuit and try it out on my FT-817.
Addendum:
Here’s the code running while hooked to my FT-817.
There is a new Google Earth app out for the iPhone. It’s pretty cool. Grab it from the Apple App store. Nuff said.
Addendum: Okay, it wasn’t really enough said. It has a great interface, which uses the touch screen and tilt sensors in the iPhone to control the panning of the display.
I don’t get much from Europe with my low antenna, but DF0HQ on 40m was booming in pretty well!
At various times I kind of wanted to write an mp3 decoder. Don’t ask why. Anywhoo…. here’s a link:
… languages which don’t implement tail recursion properly. You have no excuse. Seriously.
I’m looking at you, Python.
For the next week or so, Richard Garriot will be aboard the ISS. Richard’s dad was the first astronaut to use ham radio to talk to radio amateurs from orbit, and Richard will be operating ham radio during his stay, including the ability to send slow scan television images directly from the ISS. To get a bit of a head start, AMSAT configured AO-51 to transmit SSTV images, which I tried to record using my hand held yagi. As you can see, it wasn’t that great, but the ISS should have about 20x the radiated power, so I still might luck out and get some good images.
You can look at images as they are downloaded via the ARISS SSTV blog.
Still, it’s kind of cool.
I didn’t get a chance to watch the online webcast, but the SpaceX launch of flight 4 of their Falcon 1 launch vehicle managed to reach earth orbit, becoming the first privately developed vehicle to do so. They don’t have video up yet, but when they do, I’ll try to link it. Congratulations to the team.
Addendum: Here’s the Youtube!
I’m still playing around with GMT to generate some maps. I’m not sure I’ve really got it figured out, but here is an attempt to draw a world globe with some of the great circles that connect me to the various stations that have received my WSPR beacon messages.
Addendum: Robert pointed out that I didn’t give a link to the GMT tools. Consider this to be the remedy. They are kind of a quirky set of tools that can be used to create very nice output in a number of different projections, but they aren’t the simplest to figure out. I first learned about them from the book Mapping Hacks which is well worth owning.
Perhaps I’ll see some of you there.
Yesterday, I took the wife and the future daughter-in-law to Travis AFB for their airshow. It was a blast. Lots of cool planes, culminating in a nice show by the Air Force Thunderbirds. I snapped a lot of photos, this one probably being the best.
Courtesy of BibliOdyssey: Early Microscopes, a collection of very cool etchings showing, well, early microscopes.
Hellschreiber is a method of sending text over radio. It basically is a kind of primitive fax machine: it sends each character as a 7×14 matrix of dots. If the receiver hears a signal, it plots a dot, otherwise it plots a space. Each character is scanned left to right, bottom to top, and are sent at 2.5 chars per second.
But all this playing around with QRSS makes me want to try for something different. I wanted to send a character every 20 seconds or so, so I represent each of the 14 rows of the character by a oscillator. Each oscillator is spaced 1Hz apart. All rows for a column are thus sent simultaneously, and we send each column for three seconds.
If you don’t have any noise, it’s really easy to decode:
Same message, with lots of noise…
Here is what the audio sounds like with the noise in place. I can barely hear the signal most of the time, but it does sort of warble in every once in a while.
I’ll have to try an on-the-air test sometime soon.
Addendum: You can see little spurs at the beginning and end of each column. That’s because each of the oscillators snaps on to full volume. That generates a little click, which contains lots of energy. Slowing on that pop would help keep the signal narrow. But the reality is that in practice, it probably doesn’t matter at all.
