brainwagon

There has been a lot of work in recent years toward making amateur level UAVs. This one is a tricopter, and is completely open source. They claim that it can fly for “under $100 in parts, not including the airframe”. Sounds like a very cool project. It splits the computational load between an onboard pic that handles rate damping, PWM of the servos, and sensor capture, and a ground station computer which creates an interface and runs the navigation. Nifty.

Vicacopter.

Another one of those nifty amateur balloon launches is scheduled for next Saturday, February 6:

The vehicle will be a 1200g helium-filled latex balloon. The expected burst altitude will be 90,000 feet or higher. The flight is anticipated to last about 2.5 hours from launch to touchdown.
Payload: In addition to ANSR flight computer/cross-band repeater and beacon packages, the balloon train will carry student-built packages containing a variety of scientific apparatus as well as digital cameras to photo-document the flight.

The posting includes links to the APRS tracking pages where you could monitor the flight over the Internet.

Arizona Near Space Research | Promoting science and education by exploring frontiers in amateur radio and high altitude balloons..

I’ve got the RFSPACE SDR-IQ hooked up as a receiver again, and using it to feed WSPR. There is a ton of loud RTTY signals swamping the 40m band in the vicinity of the WSPR signals, but I’m still getting some signals. Here is the reports thusfar this evening:

Excerpt

Addendum: Picked up CX2ABP in Uraguay:

Addendum: Overnight, I picked up LA3JJ and VK4YEH among others:

Addendum: Overnight, it appears that my monitoring PC decided to download some security updates and reboot. Hence, logging ceased about 3:15AM local time. I just fired it back up, and got 7L4IOU in Japan and VK6POP in Australia.

I admit it: I’m an old timer. When I first was learning about Unix and C programming, I was sitting in front of a TVI 912 terminal (if I was lucky) or an ADM-3A (if I wasn’t lucky) that was connected to a VAX-750. I’m not overly nostalgic, but I do continue to work in much the same way, except with lots of terminals open on a much larger screen, usually with a decent fixed-width font. As a throw back to these older times, I often use green text on a dead black background.

A few months ago, I found a truly nifty font that enhances my sense of nostalgia. It’s a very cool True Type font, which is carefully designed to match the old VT220 font, complete with the “scanline” appearance that I remember. It’s actually a pretty nice legible font as well. Perhaps you’ll enjoy it.

Hacking with Style: TrueType VT220 Font.

I subscribe to quite a few mailing lists relating to ham radio. A few months back, I decided to give the QRP-L a whirl. Unlike many lists like the EMRFD list, QRP-L had a fairly high NSR (noise to signal ratio), but hey, it’s a mailing list. It doesn’t take long to skip over stuff that doesn’t interest you. It’s not worth complaining that people spend more time talking about computer viruses and which sound card interface they use than actual interesting bits of homebrewing and QRP operation.

Today, I unsubscribed not just because it was boring, but because it is whining. Not just whining, but members seem to be piling on the idea that if someone doesn’t operate in a particular way that you approve, that they are entitled to maliciously jam your transmissions.

That’s illegal. It’s also first-order dyed-in-the-wool jackassery.

Goodbye QRP-L. It was nice knowing you.

On second thought, maybe it wasn’t that nice.

Anyone who is subscribed to the QRP-L has likely been subjected to a long string of complaints against WSPR in the past week or so. This began with a generic complaint against a “consistent carrier” on 7.040. This rapidly decayed into a long series of rants against WSPR. Since I’m rather more fond of WSPR than the average QRP-L member, I chose to defend WSPR’s place in the ham radio universe.

But amidst the general complaints, there are a few points which they make which we should all take to heart. First of all, in the United States we are not allowed to operate automatic beacon transmitters below 10m. This means that you have to be in control of the station, and operate it in a manner consistent with Part 97 regulations. I’m not sure what that really means in the context of this mode, but I suspect that it means that running your beacon all night while you sleep isn’t actually legal, as fun (or useful, I would argue) as it might be to see those spots from New Zealand that occur at 4:30AM local time when you wake up and have your coffee. I believe that all hams should endeavor to operate their stations in accordance to regulations, so I think that we as WSPR operators should be at the control point of our stations when transmitting WSPR. I also think that this point of legality isn’t adequately emphasized in existing documentation, so new users of the mode may be unaware of this issue, so it would be great if we had a more prominent notice on WSJT’s site, and on wsprnet.org.

Beyond simple legality though, I’ve seen that the QRP-ers have some basis for being irritated beyond the mere legality of this operation. In the last 24 hours, I’ve logged one particular station who has operated at 100w output power, and for quite a while, was transmitting about 50% of all slots, including many back to back slots. This resulted in spots with a SNR of +5 over distances of 12000km. This isn’t a WSPR, it’s a rock concert. I think its good to keep WSPR at QRP levels or ideally QRPP levels. And let’s keep our transmit percentage down to 20% or less. As WSPR has become more popular (and it has become much more so even in the last few months, with dozens of stations on 40m and 30m) we’ll need to reduce the time we spend transmitting to mitigate collisions.

And let’s be especially careful around 40m, okay? 7.040Mhz isn’t the best choice of frequency, frankly. Lots of old time rock bound QRPers still claim it as their own, and while nobody owns a frequency, we should be courteous to all hams.

I was waiting for sleep to come, and surfed over to the American Checker Federation website. As long-time readers of this blog might remember, I’ve been tinkering a checkers program together, which I tentatively named “Milhouse” to play checkers. This week’s problem challenge was a classic 2 on 3 battle where White is to move and force a draw from the down position:

It’s late, and been a full day, so I can’t really say that I understand this position. But Milhouse doesn’t get tired: when I load the endgame database, it immediately proclaim that the position is a draw. What’s more is that it identifies two different lines: their website suggests 23-26 as a drawing move, but 19-15 is also a draw.

Without the endgame database, White thinks it is down a man, but with a 25 ply search can’t find the draw. In addition to the two moves listed above, it thinks that 23-18 is also almost as viable. But 23-18 is a dead loss, presumably because it allows Red to king both of its checkers. Even with the database though, Milhouse can’t seem to find the win for Red in a 31 ply deep search. This seems like a good test case for future improvements to playing with the database.

Roger, G3XBM has a terrific blog and website, and is always tinkering things together that I find interesting and inspiring. This morning, I see that he’s got a small 2 transistor transceiver for 80m that looks like it could be really fun, and constructed from bits you’d probably find in your junkbox. I like the circuit a bit more than the Pixie, since it doesn’t use an LM386, but that does mean that you need a high-impedance earphone because the audio power developed on receive is pretty low. On transmit, it’s basically a simple crystal oscillator, tapped on the collector. I’m a bit hazy on exactly how it operates on receive though. Of course, that means that there is an opportunity for thinking and experimentation with LTSpice. Very nifty. I might have to breadboard this one up myself.

XBM80-2 An Experimental 80m CW Transceiver G3XBM.

I was bored, tuning around when someone on the #hamradio IRC channel mentioned that the “Cuban lady” numbers station was audible around 5.883Mhz. I was bored. I recorded 10 minutes of her. Now you can be bored too.

The Cuban Lady, V2A recorded 1/22/2010, around 11:15PM PST

For fun, I’ve got my new RFSPACE SDR-IQ running on my laptop using Spectrum Lab and monitoring the 30m QRSS beacon subband. I enabled its HTTP server, and now have set up a little cronscript to copy its display to my webserver once a minute. You can see an example display below (showing KC7VHS, AA5CK and WA5DJJ) or you can click on the link below, and get the live version on QRSS.info

K6HX QRSS Grabber.

I’m not sure why the frequency display on the right is wrong. Anybody have any ideas? I probably have missed something in the configuration of Spectrum Lab, but it’s rather like operating the Space Shuttle…

Well, we are beginning to get some lightning in the area, so my radio is disconnected, but before I did so, I managed to hook Spectrum Lab up to my SDR-IQ radio, and got these two DFCW signals: KC7VHS and WA5DJJ.

Joachim, PA1GSJ has decided to put up a blog for the KnightsQRSS. I recommend all those interested in QRSS operations to go ahead and subscribe, then we’ll have a common place to talk besides the mailing list.

That reminds me, I really do need to get my own site, QRSS.info working again.

KnightsQRSS.

Paul, M1CNK, has a very nice webpage that details his QRSS beacon, constructed as several different kits assembled as modules. Very cool.

qrssbeacon (wiltonpaul).

I’m saving a link to this page, because I think I may have something misconfigured in my own attempt to use the EMU-0202 sound card for software defined radio. It’s probably not of much use to you if you don’t have that sound card, but… I do, so I am saving this.

Genesis G40 SDR Radio Transceiver QRP Kit.

Jeff (KE9V) posted an interesting commentary on an article by G4ILO about why he’s not excited by software-defined radio. My comments are mostly directed to G4ILO’s original statements.

Before I begin the rant proper though, let me say that if something in ham radio doesn’t appeal to you, you should by no means think that I’m asking you to change your feelings. Everyone is free to explore and experience their hobbies in a way that maximize their own personal enjoyment, without any kind of justification or rationalization required.

But somethings I thought that G4ILO were just a little off target, and as someone who is excited by software-defined radio, I think its good that I air the counterview.

G4ILO begins with:

I say this even though I am a programmer of sorts. I have tried to learn how SDR works with the idea that if I could write my own SDR software it might become an aspect of the hobby I could get interested in. But I can’t. The math is totally beyond me and I just can’t understand how it works at all. The majority of radio amateurs without any knowledge of programming don’t have a chance. Which makes the limit of most people’s technical challenge in an SDR future that of getting somebody else’s SDR software to work. And after a lifetime working with computers frankly I don’t find faffing about with PCs very much fun.

In some sense of course, this is entirely correct. If we compare the number of users of PSK31 to the number of people who understand the modulation technique in sufficient detail to write their own working implementation, I’d say the ratio is likely 1000:1 or 10000:1. But I think it is odd to say that someone “doesn’t have a chance” at understanding software defined radio. I’ve managed to work it out. Most software defined radios are just big down converters, using the principles of phasing that are well exposed in the ARRL handbooks and in books like Experimental Methods in Radio Frequency Design. Once you understand how the digital down conversion works, you can work on designing good low pass filters. Again, the math is a bit heavy, but it isn’t completely impenetrable. Once you have those two bits, making a SDR that receives CW and SSB signals isn’t particularly difficult. The overwhelming majority of hams won’t ever do that, but so what? Isn’t it great that we are able to do so?

G4ILO continues:

A basic understanding of electronics is one of the prerequisites of getting a ham radio license. Although most of us could not design an Elecraft K3 and many of us choose never to design or even build any part of our station, most of us can understand how radio circuits work and quite a few of us can build simple circuits from a schematic. Some of us can even design circuits from scratch – a lot more of us I’d wager than could write their own SDR software.

Again, this may be true, but I also suspect that it is because there isn’t nearly the overlap between ham radio operators and experienced software engineers. The ham radio population as a whole isn’t actually all that computer saavy: there are exceptions naturally, but in general most software written by hams is pretty crufty. Designing feedback amplifiers and impedance matching networks isn’t particularly easier than writing software defined radio software: it’s just different. Everything is hard when you don’t know how it works.

I also expect that while most hams think they understand how lots of things in their radio work, the number who actually do and are able to design bits of their own radio gear effectively is quite low. Guys like SolderSmoke’s Bill Meara who’ve been hams for 20 years are still working to really understand mixers and amplifiers, and benefit greatly from luminaries like Wes, W7ZOI and Rick, KK7B.

The reason I don’t like SDR is that it reduces the majority of us to the role of appliance operators. That may be fine for those who are happy being appliance operators and just want the best technical solution for working weak DX or amassing the most contest points. But for the tinkerers and builders SDR doesn’t leave a lot to experiment with, because most of the interesting stuff happens in software, inside the computer, where we don’t have the tools or the knowledge to tinker with it. If you are using a SoftRock or a top of the line Flex you will be looking at the same software user interface. And I don’t find that a very enthralling prospect.

The majority of amateur radios are already appliance operators. That trend is at least 40 years old, and it shows no sign of slowing. Most of the gear that you can buy now already has a large software component, hidden deep inside the unit where it is not only difficult but literally impossible for you to examine it. The glory of things like the Softrock is that even if you have a modest understanding of electronics, you can figure out what how it works, and can use your ordinary every day PC to process the signals from it. If you only use Rocky, well, then you’ve built a $15 receiver that can do AM, FM, SSB and CW with varying filters. If you examine the circuit, you”ll learn how Tayloe detectors work, and why they are a good idea. If you spend a bit more of time, you might begin to understand how sampling works, what the Nyquist limit is about, and how you can construct good heterodyne filters in software.

And frankly, the idea that software defined radios don’t leave much room for experimentation makes me blow milk out my nose. If it isn’t the kind of experimentation that you are personally interested in, so be it, but there is lots to do. I’ve been working on my own code for detecting QRSS beacon activity. I’ve got a perverse interest in modes like Hellschrieber, and thought that making a compact, self-contained rig to do Hellschrieber would be a fun thing to do, and could be powered by something as cheap and inexpensive as a dsPIC. Even if you just like RTTY, you could probably make a small self-contained rig that could decode multiple RTTY signals simultaneously. Or, you can develop (or someone can) really nice PC interfaces, like the one from sdr-radio.com. I’d like to see a SDR kit or design that includes the analog capture as well (we should stop relying on sound cards, which have characteristics which aren’t always in tune with our needs) so we can sever the ties with our laptops. I’d like to see software defined radios with wide bandwidth available at VHF+ (but perhaps cheaper than the ones available from ettus.com).

Software defined radios aren’t a panacea. They don’t solve all possible problems, or even any given problem in the best possible way. They do however give hams a set of tools and techniques that are versatile and exciting, and I welcome their addition to ham radio.