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


Association Of Rocket Mavericks

With all the pondering of satellites that I've been doing lately, it seems inevitable that I would have to develop some interest in rocketry. Here's a link to get you all started down the same path:

Association Of Rocket Mavericks

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SO-50 pass in the afternoon…

I decided I needed a break, so I wandered outside and caught the SO-50 pass from the parking lot using my TH-D7A and my trusty Arrow antenna. SO-50 has a reputation of being a bit finicky: I seem to always be struggling a bit with it, rotating my arrow can seem to either completely null the signal, or can bring it booming in, or sometimes, it just fades and is hard to locate. This pass, I also seemed to be not hearing the normal signs that I needed to tweak the Doppler until late, so it wasn't that good of a pass. Still, I managed to exchange calls with K7WIN Jeff and KC9ELU Mike (over 2000 miles). Audio follows:

SO-50 pass, Feb 26, 2008

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Try to get N3CRT on AO-51…

Got stomped. Oh well.

AO-51 Pass, February 23, 2008

Addendum: N3CRT tried to record it too. His recording is here.

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AO-16 attempt…

Well, I was going to try AO-16, but as it turns out, I forgot to charge my FT-817, so I only got six minutes of receive from it. Oh well, not too bad, after all, I needed the practice tracking the Doppler. This was the first time I got audio which wasn't complete crap. 😉 I even heard WA8SME in there! Howdy Mark.

AO-16 recording…

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Where is this fax from?

I'm a teeny bit confused. The strong source of HF-FAX transmissions that i've been recording and decoding is broadcasting at night on 8.502 Mhz. I thought (based upon some link i can no longer find) that the transmissions were coming from Australia. But this website which has a list of HF-FAX transmitters suggests that it's coming from Norfolk, VA.

There seems to be some genuine confusion. But for now, I'm going to assume it's Norfolk, not Australia.

Addendum: Or, maybe, it's the USCG in New Orleans. Sigh. In a way, that makes sense, because every map I seem to be getting shows the ocean off the Gulf of Mexico. It also matches up with this info from the USCG, which lists NMG as broadcasting on 8503.9, which means that I tune it on 8502.

Addendum2: Yep, it looks like New Orleans is where it's at. Here's a link to the schedule.. I've been doing my experiments around 11:00PM local, which is 07:00UTC. According to this schedule, at 07:25UTC, they rebroadcast the 72 hr surface forecast, which matches up nicely with what I received.

Addendum3: Here's a GOES IR image from New Orleans.


Addendum4: Here's the same image, in the pristine form you can get from the NOAA website:

Directly from the NOAA website…

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Strange Sounds From Saturn

One of the greatest science fiction movie of all time is without doubt the 1956 classic Forbidden Planet. One of the reasons it was so successful was the oddly futuristic electronic music of Louse and Bebe Barron, true pioneers in electronic music. What's really odd is that NASA's latest recording of radio signals from the Cassini probe around Saturn sounds remarkably like that music. Check it out:

Radio sounds from Saturn

Addendum: I'm apparently not the only one who noticed the striking similarity.

Thanks to Mark, WA8SME for calling my attention to this.

Addendum: Here's the spectrum of the sounds over time (going left to right in time, up in frequency).

Spectrum of the Saturn Emissions

Kind of trippy.

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More HF-Fax experimentation…

Worked a bit more on the code. It now sets the appropriate horizontal size and aspect ratio, and I tuned it to actually have the appropriate line length to keep the orientation straight.

Another decode…

It still doesn't find the sync pulse yet, but it will soon. Interestingly enough, the sound card is accurate to less than one sample in 11025, the difference between the nominal sample rate and the one that produces straight vertical lines is less than one half a sample per second. I find that pretty amazing.

Addendum: I mentioned yesterday that i was getting a much better signal from Australia than from Point Reyes. Here's an example of images that I'm getting from Pt. Reyes.

Bad image from Pt. Reyes…


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Evening programming…

Got home, and didn't feel like standing outside in the rain and wait for a satellite pass. But I did feel like doing something radio related. So, while sitting on the couch during Big Brother, and the first 10 minutes of a recorded episode of Boston Legal, I hacked together a simple program that did some of the heavy lifting in decoding an HF-FAX recording that I did yesterday. This was recorded from the Australian VMC station in Charleville. It doesn't do determine the sync rate, the aspect ratio, nor does it really work very hard to get the color ranges right, but it does give an image (and much better than the decoder that's part of cocoaModem). Witness:

HF-FAX image from Charleville, Australia

I'll undoubtedly get it working even better, but it's encouraging.

Addendum: It's odd, but I'm getting MUCH better signals from Australia than I am from Pt. Reyes. It's like I'm getting some kind of horrific multipath from the nearer site. Very odd. I'll investigate further some other time. In the mean time, I got another one, pulled it into gimp for a little fine tuning, and here's the result (there is an odd artifact that appeared in two images that I made, so something might be going slightly wrong, I'll have to check it out).

Another image received from australia, converted to a bilevel png file.

That's enough for tonight.

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Ditch the diet soda if you’re trying to lose weight

Ditch the diet soda if you're trying to lose weight

In a study to be published today, American researchers found that rats fed yogurt sweetened with zero-calorie saccharin later consumed more calories and gained more weight and body fat than rats fed yogurt sweetened with sugar.

Yep, I know, this story has nothing to do with radio. I'm back working on my diet again. During Ratatouille, I managed to get busy enough that exercise and diet began to take a back seat to other concerns, and I gained about 25 of the 70 pounds I had lost back. Sigh. I'm back at Weight Watchers now, and am down about five pounds in the last three weeks. Slow and steady.

But this report doesn't really surprise me very much: it's not at all surprising that when you refuse to feed your body with calories when it wants it, your metabolism shows and you are more likely to eat inappropriately later. We should all watch our consumption of refined sugars and starches, but substituting sugar free and fat free snacks is probably not good either.

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VP6DX Ducie Island 2008

On Saturday afternoon, I was tuning around with my FT-817, and heard VP6DX calling CQ on 20m SSB. He was working split, transmitting on 14.190 and listening on 14.245 (from memory, have the split frequency wrong). It turns out that he's part of a DXpedition: a trip by a radio amateur to go to a remote location and operate from their. It turns out that VP6DX is operating from Ducie Island, a small member of the Pitcairn islands in the south Pacific, with a total area of less than four square kilometers and no permanent inhabitants. Whacky! I wasn't really setup for transmitting, so I didn't bother trying to call him. Indeed, since the FT-817 only puts out five watts and my antenna is hardly optimal, I'm pretty sure it would be pointless, but I thought it was kind of neat to hear him.

VP6DX Ducie Island 2008 :: About Ducie Island

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More weather pictures….

Well, I decided to give NOAA 18 a try during a nice 18 degree pass. The resulting image was actually pretty good, although still spoiled in spots by some nasty interference (some of which sounded like a phone ringing, very odd). Still, I think this is th first image that I had that made it all the way up the coast to Puget Sound. Very neat.

NOAA 18 pass, South To North, on Feb 17, 2008

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Product detector and method therefor – Google Patents

Several recent direct conversion receiver designs that I have been looking at use something called a Tayloe mixer. It's an interesting way to construct a mixer. It turns out, it's covered by a patent.

Here's a link to it.

Text not available
Product detector and method therefor Daniel Richard Tayloe

I found the patent number while reading up on the QRP2001 design.

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Evening satellite passes…

Sigh. Just went out to try to work AO-51, couldn't hear anything from the satellite, nor could I raise it. It was only after I got back inside that I remembered that the powers that be had scheduled some days where the 1.2ghz uplink was active. Sadly, that means that while passing by California, not a single ham with the necessary equipment chose to work the uplink.

SO-50 pass coming up shortly.

Addendum: Got W5YM, AD7ZQ and XE2BL.

SO-50 Pass…

Addendum2: Spent some more time playing around with cocoaModem. Looking for PSK31 signals, I actually had the best luck on 80m, which was suprisingly un-noisy and had quite a few signals, even though I just had a 20m dipole up. Here's a screengrab:

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Well, I was playing around with cocoaModem a bit more, and decided to try to decode some of the HF-FAX images sent by the station here in Point Reyes. The quality isn't quite what I would imagine it should be, and there were a number of sync issues, so I'm not sure what's going on here. But here's the very first image I decoded: the bar in the center is when I tried to shift it into DIGITAL mode on the FT-817, which didn't work very well.

HF Fax Image from Point Reyes, my first

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Another night pass on AO-51…

Well, beneath a beautiful crescent moon and a stunning view of Orion, I set up to work AO-51 again. Sadly, on the eastern pass I suffered the usual fate of handheld users: totally dominated by users who feel that because they have more power, they don't need to yield to others. I usually have a little better time with the western passes, so I worked that. Interestingly enough, just as the satellite came up, I heard UT1FG calling CQ SATELLITE from BM83: a maritime mobile contact! Sadly, he was your classic alligator: all mouth, no ears. Somehow W6ASL managed to get his attention and complete a QSO, but he didn't respond to the dozens of other attempts that people made. Somewhere in the middle of this, I managed to get a QSO from VE4NSA in Manitoba.

AO-51, Western Pass, Evening of Feb 10.

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