brainwagon "There is much pleasure in useless knowledge." — Bertrand Russell


Rings ‘n things…

Last night, I took the scope out again and tried to get a few quick images of Saturn. My focus was really soft, but this was what I came up with after processing the video with Registax. It's actually pretty comparable to the level of detail that I could see through the Meade ETX 90 under the conditions we had, which wasn't too bad really.

I'll try to type up a longer post about this later.

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First astrophotography with the Microsoft Cinema HD webcam…

A couple of days ago, I mentioned that I had gotten a Microsoft Cinema HD webcam to convert for use in astrophotography. Today, I got my Meade ETX-90 out, and decided to give it a test on the daytime moon. Sadly, my mount's tracking capabilities seem to be pretty glitchy: the autostar seems to be resetting at odd intervals, probably a power issue. So, I just recorded some short video using SharpCap and letting the Earth's rotation carry the image across the sensor. Here's an example of the raw footage, recorded at 800x600.

Pretty wavy, awfully blue, and not that impressive. But luckily, processing with modern image stacking software can work wonders. I used VirtualDub to save the images as an image sequence, and then used AviStack to analyze and stack the resulting images, followed by some contrast enhancement and wavelet filtering. Here's the result:

Moon, through my ETX-90, after processing.

Since, I'm going to take pictures, I should probably learn some of the names of the major lunar features. The large, smooth area in the center is the Mare Nectaris. The large crater with the central peak is Theophilus, which overlaps Cyrillus. The tiny crater in the middle of the sea is Rosse, and for a sense of scale, is about 12km across. The crater near the top that seems to have the Mare Nectaris flowing into it is Fracastorius.

Some other footage I snapped resulted in some other nice images:

Another image, showing the region around Piccolomini A-E.

This shows the area further south (which is toward the top, which includes the crater Piccolomini, and it's associated overlapping satellite impact craters.

Not bad for a first try. I wonder what I could accomplish with real equipment.

Addendum: Try rewatching the video above, watching carefully for the Rosse crater in the middle of Mare Nectaris. It flickers into view just a few times in the five second capture, but is a clear and obvious feature in the processed video. Pretty neat.

Filed under: Astronomy 1 Comment

Happy Birthday Alan Turing…

Today would have marked the 100th birthday of Alan Turing. Turing's contributions in artificial intelligence and computing alone would have guaranteed his place among the greatest thinkers of the 20th century, but that was only a small part of his genius. His pioneering work on cryptography at Bletchley Park allowed the British to crack the German Enigma code, with the likely result of shortening the war by years, saving millions of lives. Tragically, he was persecuted for his homosexuality, and committed suicide before his 42nd birthday. The savior of millions could not find acceptance in the society he helped preserve.

In a 2009 official apology from the British government:

Thousands of people have come together to demand justice for Alan Turing and recognition of the appalling way he was treated. While Turing was dealt with under the law of the time and we can't put the clock back, his treatment was of course utterly unfair and I am pleased to have the chance to say how deeply sorry I and we all are for what happened to him ... So on behalf of the British government, and all those who live freely thanks to Alan's work I am very proud to say: we're sorry, you deserved so much better.
Prime Minister Gordon Brown, 2009

Amen. Happy Birthday, Alan.

Filed under: Amateur Radio 1 Comment

Adapting a webcam for telescope use…

Over the last few weeks, I've been a bit more intrigued by one of my old interests: telescopes and astrophotography. During the transit of Venus, I hooked up an old black and white video camera, and tried to take some snapshots, but wasn't really pleased with the results. So, I decided to try to adapt a webcam for telescope use. A bit of research online said that the Microsoft Lifecam Cinema HD was a good choice, and an adapter was available that should make a nice, lightweight camera.

The Microsoft Lifecam Cinema HD is very small, nearly ideal package, but you do have to do some modifications to get it into the barrel and adapt it for telescope use. You can find some of the rough instructions here: you need to disassemble the camera, remove the button and microphone, and then get rid of the lens and IR filter. When you are done, you reassemble it, and it slides into the Billet Parts adapter just as neat as you please and is held in place by an O-ring in front and the back screwing in the back. A very tidy package. Oh, and you probably want to get rid of the bright blue led that remains on the front panel. I took an Exacto knife and just cut it off.

Here are some pictures of the assembled package:

Here are a couple of the pictures I snapped from it after plugging it into a 6" f/5 reflector I have, and aiming it by hand up the hill. Without a tripod, it wasn't possible to focus it accurately, but it gives you an idea about what the capabilities are. The colors are wacky precisely because the IR filter of the camera was removed, and it's a very bright and warm sunny day here.

Twigs on the hill about 100 feet away...

Leaves against the sky, again about 100 feet away

I'll try to get it hooked up for some real imaging this weekend. Stay tuned.

Filed under: Astronomy 1 Comment

A few more notes on the OpenBeacon…

A few days ago I wrote about my experience building the OpenBeacon, and Jason Mildrum, NT7S, it's creator was nice enough to happen by my blog and leave a comment. In that original article, I said that the instructions were (and I quote) "barely adequate". Jason asked (perhaps more politely than was truly deserved) what I meant and how he could make the instructions clearer so that someone could build the kit with greater confidence.

A very class act, I must say.

First, I should mention that I find no mistakes in the instructions. I built it as described, and it worked the very first time. I don't think any experienced kit builder will have any difficulty getting the kit to work.

But I think instructions as they written make assembly a little less smooth than they could be. Here are my specific suggestions.

  • First, I thought it was odd that the BOM was the only place that you could find the component values. For instance, if you are marching down the component list, and you see you need to install Q4, you have to refer to a different document (in my video, you can see me hopping back and forth on my iPad) to find out what Q4 actually is. It really wouldn't be that hard to expand each of these with the actual component value in line.
  • It would be nice to clarify the general way idea of how it's going to be assembled. First the USB/Microcontroller. Then the oscillator. Then the power amp. Although I actually found it simpler to mount pretty much all the caps and resistors first, and then worry about the rest, but that's nit picking. It would also be nice to have a diagram showing the components installed in each stage to help you navigate a bit easier and check for errors.
  • I built the kit while working from the BOM as it was displayed on my iPad, but I kind of like instructions that have a checklist that you can check off as you do each part. Helps keep me organized.
  • Link the schematic on the same page. At one point I powered on the microcontroller, and D7 wasn't lit. I consulted the schematic, and then realized that it was driven by the 2N7000, which I had forgotten to install. It would be nice to have that handy.
  • The troubleshooting page is linked from the top of the page, which isn't typically where you need it (put a link at each place where you make a check perhaps). When a check fails, you won't have to search for where to go.

For all that, I'm nitpicking: I shouldn't have used the words "barely adequate". They are entirely adequate, just not as conveniently organized as I would like. I think a section describing a calibration procedure for the WSPR mode might be nice too.

My OpenBeacon is off the air until next week, but expect it back shortly, in a more temperature-controlled enclosure. And thanks to Jason for the cool kit.

Filed under: Amateur Radio 2 Comments

Still from a video snap of the Venus Transit

I did try to take some video of the transit, but the higher magnification created by the rather small imager in the video camera, combined with too much AGC and a lot of wind buffeting didn't make for very interesting imagery compared to the surprisingly excellent iphone snaps I had before. But just to give you an idea of what they look like, here are a couple of snaps...

Shot with my P23C video camera from Supercircuits...

Another, nearly identical image... same setup.

About all these are good for is judging the relative apparent size of the sun with Venus. But it was a fun outing.

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iPhone photos of the Venus transit…

Yesterday, I setup my Meade ETX-90 outside with a solar filter in the courtyard between buildings at work so that my coworkers could have a glimpse of this rather rare astronomical event. I had a pretty steady stream of people coming out to have a peek throughout the day. I managed to shoot some video of it as an experiment, but again, wind buffeting and the like made focus difficult and the overall image was pretty bouncy.

But David Munier, one of my coworkers spent a few minutes clicking away by holding his iPhone at the eyepiece, and came away with these two awesome pictures! Very, very nice! I normally call this style of astrophotography "ghetto astrophotography", but I think these are good enough to just call them astrophotographs.

Not bad, for an iPhone!

Even better! Great job, Dave!

The blue blobs are light flare from reflections near the eyepiece, but they look kind of cool!

I've got some more photos and stuff that I'll try to get up shortly, but until then, enjoy!

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First reception report for the K6HX OpenBeacon…

The honor goes to Chris, WB5FKC. Chris and I exchanged signal reports occasionally back when I last was on the QRSS kick a couple of years ago, so it was nice and fitting that he was the first to spot me again. The signal is pretty rocky, but the power level here is just 100mw, which is just 1/50th the power of the previous 5W that I commonly used for QRSS back then.

I don't know if I could have spotted this, but here is the screen grab that Chris sent me:

First spot!

I thought I would be transmitting about 35hz lower than is shown here. I'll have to look into that more.

Thanks Chris, and good to be heard by you again, OM! 🙂


My OpenBeacon is on the air…

Sometime last week, I got my Etherkit OpenBeacon kit in the mail. Like many of my projects, it was probably destined to sit on the shelf for some time, but in a fit of personal productivity (for a loose definition of productivity) this week I cleared a few hours of my time and got it assembled, and now is on the air with the cloud warming power of 100mw. I positioned it's signal in the middle of a bunch of QRSS signals as received by my IC-735, so it should be within the QRSS sub-band on 30m, but my IC-735 itself is rather poorly calibrated (off by 150 Hz or so) so I'm not as yet certain of it's exact frequency. But it should be in the ballpark. I'd love to here from anyone who hears it and can provide a signal report. It's currently sending DFCW3.

But I got ahead of myself. About the kit: it is a very nice PC board, well laid out and not too cramped. All components are traditional through-hole. It requires that you wind three toroidal coils: two ordinary ones with sixteen turns, and one bifilar transformer of ten turns. If you haven't wound coils before (and I've only wound a few) you probably will find that the most daunting part of the construction.

The instructions are.. well... I'd characterize them as barely adequate. They consist mostly of a BOM and a few rough pointers. If you look carefully, you can install things incrementally, but it's kind of a pain to do things that way. I began by simply installing all the caps and resistors, and then enough to test the microcontroller was functional. The board uses an ATtiny85 by Atmel, and runs software which allows it to appear as a USB device. That all worked fine the first time I booted it up, no great surprises. When I finished fleshing out the oscillator, I was slightly confused because it didn't appear to start, and I noticed that the red LED indicator wasn't on. A bit more careful examination of the schematic showed that unless the 2N7000 was installed that would probably be the case, so I ignored it and simply fleshed out the rest of the rig. In the end, it all turned out fine. I think they could be a bit clearer on how to mount the power transistor: the double line indicates the backside (non-label side) of the transistor. That would be easy to screw up if you weren't careful.

When I powered it on, I could hear it's signal about 4Khz low on my IC-735, even without any antenna hooked up. You have three adjustments: one cap controls the frequency, one controls the bandwidth of the modulated signal, and a trim pot controls the output power. By the time I finished this, I was a bit tired, and didn't have much desire to do detailed testing. I hooked up my SDR-IQ to accurately measure the output frequency, and tweaked it to be right around 10.140000 Mhz. The tuning is fairly twitchy, even small turns of the tuning cap can send the oscillator two or three hundred hertz from where you start. But with the SDR-IQ, you can watch fairly easily, and I soon had it on frequency.

I didn't have a dummy load or anything yesterday, but I put it on the air. I didn't see any sign of it on W4HBK's Florida grabber (most closer ones appear to be off the air for now), but I think it was all working.

Today, I wanted to make a more accurate estimate of the output power. I constructed a small dummy load out of 4 180 ohm resistors wired in parallel (yes, that's just 45 ohms, so sue me). I then clipped my handy Rigol scope on either side of the resistors, and measured the RMS voltage. Setting it to 4.5V into a 45 ohm load should make for 100mw. I also checked the limits: right around 300mw, just as described in the documentation.

Here are a couple of screen grabs that I made using Spectran while testing the beacon. The first shows it's default DFCW3 signal, the second, the somewhat less effective but still cooler looking Hellschrieber.

Spectran showing my DFCW3 callsign...

Testing the multi-tone Hellschreiber mode..

I also recorded part of me assembling it in time lapse mode on my iPhone. Not informative, but fun to watch. Sadly, my batteries died before finishing it, next time I'll use an A/C adapter on the phone. The utility I used OSnap! is nice, but very slow in constructing the video and uploading the results to YouTube.

I'll try to follow up with more information about this project in the near future.


No Saturn, but how ’bout the moon?

I thought I'd give my video camera a test. I considered Saturn, but by the time I got outside the weather was getting colder and blustery, and I wasn't feeling very good, so I just managed to snap some quick video of the moon. The wind was buffeting the telescope, and I was impatient, but I snagged some video and then used Registax 6 to make the best of a sorry collection. Here's the result of my amateurish efforts:

The video camera is probably a mistake: even with the mods that I put in, the AGC gets in the way, and the capture seems to have an interlacing problem that causes nothing but trouble. Perhaps it's time to get a decent webcam + adapter and try the same. Oh well. More when I get better.

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Prepping for the upcoming transit of Venus…

I've been pretty quiet on the blog, but I'm trying to get some projects going. This week marks a rather rare event: the Tuesday (for us in North America) transit of Venus across the front of the sun. According to this transit calculator, the transit will occur between 3:06 and 9:47 (well after sunset).

Back on Nov 15, 1999, I observed a transit of the planet Mercury across the sun. I snapped a few pictures, and created this rather unimpressive animated GIF:

Nov. 15, 1999 transit of Mercury in front of the sun

I don't even recall what crude webcam setup I had back then.

I think that I can do better this time. You may have seen my "ghetto" astrophotographs of the solar eclipse a couple of weeks ago. I shot those using a solar filter over my little Meade Maksutov. I though I'd press it into service again, but instead of doing the crazy "catch as you can" approach of clicking away with a hand held point and shoot at the eyepiece, I thought I'd dig up something better.

Better in this case was an old black and white security camera that I had bought from Supercircuits years ago with the idea of doing some video astronomy. I even modified the camera to allow the disabling of its automatic gain circuitry, which typically is useless for astronomy, as it causes the camera to overexpose everything you wish to see. More digging found the other necessary bits (various camera adapters and the like). I wanted to capture images to my laptop, so I needed a little Video->USB capture card. A quick trip to Fry's netted me a MyGico Capit card for the princely sum of $20, with a $15 rebate. It took me a couple of tries to get the drivers installed, but it seemed to work okay. I then aimed my rig out the window up my hill, and shot this picture of the fencepost at the back of my property:

My fencepost, viewed through the Maksutov/Video Camera setup

The focus wasn't perfect, but I could actually see an ant crawling around on it. Not bad. Not bad at all.

Except for one thing. The distance to the post is about 135 feet, and the post is a 4x4. A little math works out the field of view of this camera as being roughly .2 degrees. The sun is roughly one half a degree in size. This means that whatever I do, I won't get a full disk image of the sun. That's kind of a bummer.

Of course, I could have made a math error. I'll drag this rig out into the sunshine and see if I can shoot some pictures/vids of the sun today (should see some sunspots anyway) and see how close my math is.

I'll try to shoot some Youtube video that will further document this setup later. Stay tuned.

Filed under: Astronomy No Comments