brainwagon

I hooked up my MFJ antenna analyzer to my dipole, and wrote down the R and X measurements (resistance and reactive impedances) from 7.0 to 7.35Mhz. WIthout further comment, here is the graph.

While working on my Morse practice generating program that I have tentatively called mscript, I decided that I wanted to support “Farnsworth” timing: basically sending characters at one rate, but then increasing the spacing between characters and words so that the overall rate was slower. The idea (as near as I can tell, completely untested but still probably sensible) is that by learning the sound of characters at a fast rate, you don’t plateau as readily.

It isn’t hard to figure out the timing of traditional Morse code: A dit lasts one time period. A dash is three times as long. All elemtents (dots and dashes) within a character are separated by one period. Characters are separated by three periods. Words are separated by seven periods. Using this, the word “PARIS” takes 50 time periods, so the length of each period is 1200 / WPM milliseconds when WPM denotes the desired speed in words per minute.

But how does his timing change with the Farnsworth spacing? Well, inside a given character, the timing all remains the same. We’d like to extend intra and interword spacings to slow the overall code down to a different rate. We’d also like to preserve the 3/7 ratio between those two intervals. The math was eluding me, so I did what all people do when they don’t know the answer to a question: I looked it up on the internet. And of course, if you ask the right question, you get the right answer. Mine came in the form of an article by Jon Bloom, KE3Z that appeared in QEX entitled A Standard for Morse Timing Using the Farnsworth Technique which you can get from the ARRL archive here if you are a member.

But if you can’t, here are the formulas. Let’s say that you are specifying the Farnsworth in terms of a ratio s/c, where s is the overall (slower speed) and c is the character speed in WPM. You then compute

t_a = (60 c – 37.2 s) / (s * c)
t_c = 3 * t_a / 19
t_w = 7 * t_a / 19

where t_c and t_w are the times (in seconds) that you have between characters and words respectively.

I’ll get this hacked into mscript shortly, and post an example.

Addendum: I’ve got the code added into mscript. Here are two samples of six random five-letter groups, sent first at 20wpm, and secondly sent at 20wpm, but with character spacing increased to slow the overall rate to 10wpm.

An example of both conventional timing and Farnsworth timing.

A while ago, I bought an MFJ antenna analzyer, but I hadn’t really done much with it. I wanted a short, simple project over the weekend, so I decided to check out my 40m dipole. A quick sweep revealed that it was resonant off the top end of 40m, around 7.350 or so, and that down at the bottom end of the CW portion of the band, it was about a 3:1 SWR. I’ll take better notes later tonight when I get home, and maybe even produce a small graph.

This dipole is actually a premanufactured one from radiowavz.com. It’s just a basic 40m dipole with balun, fed by 50 ohm coax. In my case, its mounted quite low: Its about 20 feet off the ground at one end, but it is tied to a short tree up my hill. so the middle is maybe 10 feet above ground, and the far end maybe only 6 feet.

So, the open question is: will raising the far end of the antenna lower its resonant frequency? Or is the antenna just cut wrong for the CW portion of the band?

Bets anyone?

Addendum: This website does show that as the antenna gets lower, the feedpoint impedance drops significantly, and also shows that dependent on height, the resonant frequency of the antenna can vary by more than 100khz. This suggests (unsurprisingly) that I should try to mount this antenna higher to provide an easier match in the 40m band. It also suggests that measuring an antenna close to the ground isn’t a good idea.

Bruce, VE9QRP has been experimenting with using a small Atmel controller to implement the Plan 13 algorithm that provides satellite tracking and Doppler calculations (the same algorithm that I use in my own Python code). It seems silly to drag a laptop into the field to do Doppler tuning when a couple of dollars worth of silicon can easily do the calculations necessary to provide full Doppler tuning. Wouldn’t it be awesome if your rig could do this “out of the box”?

Allright, I’m probably the last ham on the planet who doesn’t know about this one, but just in case there is one other out there, I thought I’d give a plug to the ICQ Podcast. I found this while trying to find other podcasts for people trying to learn Morse Code. It is a terrific combination of new and just general conversation about ham radio, done by a group of UK hams. Well worth listening too, I got hooked on the latest episode, but am now downloading the entire catalog of back issues for my boring commute hours. Thanks alot to all the contributers, it’s really awesome.

ICQ Podcast – Home.

Well, I’m about to embark upon a new experiment. My weight has crept back up to where it was when I first joined Weight Watchers six years ago. I peaked probably near 325 or even higher, but was around 307 when I started with Weight Watchers. I eventually trimmed down to a little over 260, but lost movitation as my efforts to go lower stalled, and of course, once you feel like you stalled, my weight slowly has crept back up to higher levels, and this morning I’m nudging in at around 303 lbs.

Yes, I’m unflinchingly telling you those numbers. Okay, I’m flinching a tiny bit. Many people gasp when they hear that number. Hey, I’m 6′4″ tall too, so it isn’t as bad as it could be. Still, I cringe a bit inside when I see that “3″ at the beginning of my weight, largely because I know that it probably means that my blood pressure and cholesterol levels could use some work too.

Anywhere, there’s the setup. Here’s the new experiment: I’ve acquired a wifi enabled scale from withings.com. I blame Leo Laporte, because he mentioned he got one, and I decided that I would give it a shot. One of the interesting things about this scale is that you can set it up to echo your weight to both their own site, to Google Health, or to (gasp!) Twitter.

So, I’ve created a new twitter login called marks_mass to serve as the output for this device. Each morning I’m going to hop on the scale and get a weight + BMI reading, which will get echoed onto my twitter account (right now it seems to just be sending my weight, I’ll see if I can change that, I’m still getting acquainted with the device). And, all of my followers will be able to see what I weigh.

Here’s where you come in: if you have a reaction, positive, negative, doesn’t really matter, go ahead and respond to marks_mass. Send encouragement. Send disappointment. Send advice. I’m opening this up to harness the power of my peers to help me change my own attitudes and behavior.

Welcome to my grand experiment.

Click here if you want to see marks_mass, and if you like, you can become a follower.

Addendum:
I should also give a brief mention to the device. It’s a really nice little gadget, much nicer than any other bathroom scale I’ve had before. It’s got a very sleek black finish and a bright display that I can read easily when you stop on it. If you step on it with bare feet, it will weigh you, and if you continue to stand, will give you a progress bar as it determines your BMI. Setup for the WiFi was similarly simple. You go to their website, download an installer for PC/Mac. You then do a one time configuration by plugging it into your PC, which pairs it to your wireless access point and gets it registered. You can then create a profile, and use it to start monitoring your weight. (All future configurations are done over the Internet.) I’m quite pleased with the device thusfar.

Addendum²: Oh, and there’s an iPhone app too.

This morning greeted me with this nice little video, where Diana Eng demonstrates the pattern generated by dipole and Yagi antennas by a simple detector consisting of a dipole antenna with a small flashlight bulb wired across the feed point:

It does actually uncover one of my pet peeves: in describing the action of the reflector element of the Yagi, Diane claims that the reflector “reflects”, but when she added a director, she claimed that the director “focuses”. But if you are a clever person who maybe doesn’t understand much about how antennas work, you might reasonably ask how that actually works. After all, the elements are identical in composition, and are essentially placed the same distance from the antenna. Why does the director direct, but the reflector reflect?

If you can actually answer this question, you’ve begun to understand how antennas really work.

Well, there wasn’t anything terrific on TV tonight, and I’ve had a little program kicking around in my head for a while, so I decided to set down and see if I could make some headway on it in a single evening of programming.

I used to have some Morse code practice cassette tapes a while ago. It used the Koch method, and was progressive. They began with just two letters, say K and M that were sent using Koch spacing (the space between letters were sent as if they were 5wpm, but the letters themselves were sent at 13wpm.) The tapes themselves were thus the combination of regular speech (giving you instructions) and Morse code. But I can’t find the tapes anymore, and even if I did have the tapes, I don’t have a cassette player, so they wouldn’t be of any immediate use. I went to HRO to see if they had any such thing on CD so that I could listen to them in my car, but ironically, the bottom seems to have fallen out of the Morse Code CD market, and they didn’t have any in stock.

So, I thought to myself, what would it take to make my own?

I’ve written programs to generate Morse code before. And most of the computers I use have some kind of speech synthesis capability (either the “say” command on Mac OS, or the festival speech synthesizer on Linux) so generating some reasonable if not exactly pleasing speech wouldn’t be that hard.

So, I tossed together a simple scripting language to wire the two together. It takes a simple script which consists of text which it translates directly into Morse code. The exception is any text which appears in double quotes. It gathers that text up, and passes it to the system speech synthesizer, and generates a sound file, which it then reopens, resamples to the same output rate as the rest of the morse code, and then returns to Morse mode. This isn’t all that hard because of the excellent libsndfile and libsamplerate libraries. There is some work left to be done, but the basics work. Here is the contents of a simple test script that I wrote:


"This is a test of the emergency broadcast system."
If this had been an actual emergency,
you would not have been using Morse code.


And here is the resulting .mp3 file, synthesized on my Macbook:

Morse synthesized by my “mscript” program (MP3)

The basics all work, but there are some additions to be made, to insert arbitrary wav files perhaps, to adjust timing, to implement Koch spacing and flexibility in changing the speed of Morse code inside a single document, and just other bits of cleanliness. Oh, and the Morse doesn’t have any shaping at all, so the transitions are a bit clicky. I can fix that pretty easily. Still, not bad for a couple of hours of tinkering with C, yacc, and lex.

Poking around on archive.org, I found that Louis Bell’s classic work The Telescope was available for download. It is a pretty nice book, well worth reading if one has an interest in astronomy and telescopes. It is part history, part engineering, and part user’s guide. It also includes some great illustrations such as the one below of Newton’s first reflecting telescope. Enjoy!

Internet Archive: Free Download: The telescope.

Tonight, I’m currently hearing station DP1POL, from grid IB59uh on 40m. Where is that, you might ask? Antarctica. He’s heard my beacon before, but I think this is the first time that I’ve received him. The distance is nearly 15,000 km. Verah nice.

Yep, it’s that time again when the Oscar nominations are announced, and once again my Pixarian overlords are nominated for no less than five Oscars for their movie Up. This extraordinary achievement seems almost mundane: you expect to see nominations for Best Animated Feature, and probably for Music or Sound Editing. Even one for Writing (we have some terrific writers). But what’s pretty amazing is that Up shares a Best Picture nomination with nine other films. There are those who said (along with me) that it was impossible for an animated film to get a best picture nomination now that the Best Animated Feature category exists. Guess I was wrong.

Oscar.com – Nominations – Nominated Films.

Congratulations to my fellow Pixarians.

Addendum: I hadn’t heard that there would be ten best picture nominees this year. Here’s the press release that announced it.

The more things change, the more things stay the same:

MR. B. N. BURGLUND, whose description of the wireless station at the University of Michigan, appeared in our March number, writes us an interesting letter on the part played by wireless amateurs during the recent floods in the Middle West in March. He has much to say in praise of those who did good work and rendered efficient service; and he also condemns, in no uncertain terms, the meddler who, we are sorry to admit, appears to be always on the job and gets in his fine work at such times. One of these individuals, possessed of a powerful transmitter, and ignorant of the code except to the extent of being able to recognize a few well-known calls when he heard them, persisted in calling the station at the University of Michigan while the operator there was trying to handle messages from the flooded districts. He was told, repeatedly, to keep out, but being ignorant of what was said to him, and thinking his calls were simply being recognized, kept on calling. And he kept it up for over six hours. The wireless law provides a heavy penalty for offenses of this sort, but he did not sign an understandable call and will probably never be caught.

via The Wireless Amateur in Times of Disaster (1913).

The early history of radio is quite fascinating, and luckily, lots of books from this early period are out of copyright and are available for free on the Internet. As an example, check out The book of wireless telegraph and telephone by A. F. Collins. This was radio in its infancy, when the use of vacuum tubes to create continuous oscillations was “the new wireless”, and the majority of stations were still using spark gaps. While you can’t legally operate spark anymore, it is still interesting to read these kinds of books, which offered pragmatic advice to the experimenters of the day on how they could construct and deploy their own wireless stations. Very nice.

The book of wireless telegraph and telephone : being a clear description of wireless telgraph and telephone sets and how to make and operate them, together with a simple explanation of how wireless works.

If you are a long time reader of this blog, you know that it wasn’t always about ham radio. It’s really about whatever I happen to be thinking about and doing that I wish to share and talk about. Tonight’s topic was simply this: applesauce.

I was watching America’s Test Kitchen, where they were making homemade “shake n’ bake” style porkchops and applesauce. I didn’t really feel like having porkchops, but because I’ve been eating poorly lately (too many restaurants because of visiting son and his wife, and my own visits to my brother) I had a bit of a sweet tooth, and the idea of making some homemade applesauce sounded really good, and much better for me than the ice cream which I’ve been indulging far too often in lately.

If you buy applesauce in a can or jar, far too often it suffers from a number of problems. It can be made from apples which just aren’t very good. It’s often far too sweet, with lots of high fructose corn syrup. It can have preservatives or other additives. Often it includes overpowering spice elements like cinnamon. Yuck.

America’s Test Kitchen suggested a very simple recipe. Take 4 pounds of apples. Wash them, core them, and dice them into coarse chunks (skin on). Put them in a pot. Add 1/2 a cup of sugar, a pinch of salt, and a little water. Cook for around 15 minutes, until the apples are soft, and then put them through a food mill to remove the skins and even the texture.

They suggested a number of different apples that could be used. For my experiment, I used eight of the Pink Lady variety. They are related to the Golden Delicious, but have a nice rosy color to them that’s pretty. Eight of them was about 3.5 pounds uncored. I chopped them fairly coarsely, added a splash of water, a pinch of salt, and just a little sugar (no, didn’t measure, but probably less than 1/2 a cup, maybe just two table spoons). I set this covered on medium heat.

After a few minutes, you could smell a cider-like smell, and the apples began to boil and liberate a lot of water. I thought that maybe I had too much water, but after a few more minutes, the apples began to break down and lots of the liquid was reabsorbed. After about 15 or 20 minutes, the apples were soft and smelled delicious.

I don’t have a proper food mill, so I just took a potato masher and crushed ‘em. Yep, skins still on, but as I mashed them, they lent their rosy color to the mash, and I actually liked the textural element. I added a very small amount of cinnamon, stirred it in, and then let it cool for a couple of minutes.

It was delicious. What’s really great is how the fresh complex flavor of the apples really come out. They are sweet, and tart, and clean tasting. Next time I make pork chops, I’ll have to make some of this applesauce. I think it would also be good with a scoop of good vanilla ice cream, or maybe with a cobbler like topping of oatmeal and brown sugar and maybe some cold cream.

We don’t appreciate these classic foods very often, at least in the way that they used to be made. Thanks to America’s Test Kitchen for motivating this delicious culinary experiment.

If you haven’t had a chance yet, try checking out Jack Dunigan’s HAMRADIOSAFARI.COM blog. He’s (from his sidebar) the Senior Management Leader of Aidchild Inc., a project which provides homes for children for orphans living with AIDS in Uganda. While that’s important far in excess of anything having to do with ham radio, he is also a dedicated radio amateur, and has taken to blogging his ham radio adventure in Uganda. Building antennas, assembling a Tuna Tin 2, making a PTT switch, and even the adventure of getting licensed and (unfortunately) dealing with malaria have all been subjects.

Put it in your daily list of reading. And Jack, if you are reading this, best wishes to your endeavors, ham radio related and otherwise.