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JGR and NCJ

February 29th, 2008

This week has been a banner week in the publication department.  On Tuesday, we got the proof of our paper “Optical observations of the growth and day-to-day variability of equatorial plasma bubbles” back from Journal of Geophysical Research.  On Thursday, I completed the final draft of “A multi-instrument technique for localization of equatorial ionospheric scintillations” which will go either to JGR or Radio Science on Monday.  And, also on Thursday, the National Contest Journal showed up with my article on bandpass filters and switching.

Unfortunately, I’m not completely happy with the NCJ article from a variety of standpoints.  I don’t believe it represents my best work, and I tried to cover too much too quickly.  I’m not really an expert on filters, either, just a cheap ham (that is, poor grad student) trying to do SO2R on a budget.  Perhaps I should have taken that tact.  Live and learn.  On the bright side, Zack Lau, W1VT, sent me a couple of QEX articles he’s written on filters for in-band operation.  I’ll have to look into those.  I hope to put an errata/bonus material page for the article on the filters part of the site.

Back to the grind of crunching numbers so I can write about them…I guess that outlook sounds bleaker than it really is!

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Posted in communication, engineering, radio

NAQP and LoTW

January 16th, 2008

I entered the North American QSO Party CW Contest somewhat seriously for only the second time last Saturday.  I’m pretty happy with the results, especially considering that this score is 50% higher than my claimed score the last time.  I ended up with only 9.5 hours due to the 160 antenna situation.

Summary:
Band QSOs Mults
-------------------
160: 33 20
80: 279 47
40: 261 51
20: 66 29
15: 17 5
10: 1 1
-------------------
Total: 657 153 Total Score = 100,521

Ten and fifteen meters stunk…no big surprise here for this part of the solar cycle.  Although, I would liked to have done better on fifteen.  I took my off times (an hour each time) during the second and sixth hours of the contest.  I don’t know if I would do it that way again;  I had a really good run on 40 during the day.  I tried to work the second radio then; but, I haven’t mastered that, yet.  The first hour had the worst (< 60) rate.  I did much better after that.  My totals on 40 and 80 are within striking distance of the big guys like W9RE.  But, I just don’t have the firepower on the high bands nor the ears on 160 to do well there.  Of course, there’s still the whole skill problem, too…

Topband was a disappointment…I was hoping for about 40 multipliers and 100 QSOs.  I hauled an MFJ tuner up on the roof late in the contest to load-up the 80-meter dipole and feeder against a single elevated radial on 160 since I still don’t have that automated.  That could be a tonight project.  The noise on 160 on the vertical was 10-15 dB over S9.  Those 33 contacts were fought hard by me.  I need some RX antennas.  I talked to K9AN yesterday.  He suggested a K9AY loop.  I’m thinking about active verticals with a variable phasing combiner…less footprint.  We talked about pre-amps.  He wants to measure the NF of whatever I come up with out of J310’s from my junk box.

I requested a new LoTW certificate this morning since mine expired in January 2006.  Hehe…oops.  They protect your QSO integrity like Fort Knox!  In fact, they probably have a better idea of who you are than most credit bureaus.  I need to go through my logs tonight and clean everything up to get ready.  It sure beats QSLing, though…  I’m sure I’ll make a bunch of people happy in a few weeks.

Also came up with a great SDR idea yesterday that could be my new secret weapon.  It should be pretty easy to do, too.  No more on that until I get one working…

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Posted in computing, engineering, radio

More on the fundamentals: a story and confession

January 10th, 2008

Anyone (does anyone actually read it with regularity?) who reads this blog is familiar with my rant about the “decline of the fundamentals.” Here is a story about a recent antenna project and how trying to circumvent the fundamentals came back to bite me…

One of the perennial problems for hams on small city lots (and worse, rental property) is the installation of effective HF antenna systems. My current lot is about 170’x 100’…substantial for a city lot. But, it has a 1500-sq-ft duplex plus a two-car garage. There are streets on two sides and the (above-ground) power line comes in from the corner opposite the streets. There are four large trees ranging from about 40-70 feet tall, approximately forming a 70-ft square (yes, I know 80-meter 4-square).

I recently installed a 40-meter dipole between two of the trees and an inverted-L for 160 meters between another pair. These were decent antennas, all things considered. I worked EU on 160 and could actually hold a frequency on 40 in the CW SS. I’ve had two 80-meter antennas since we moved here. The first was a killer…a 40-ft top-loaded vertical with lots of radials where the garden is now. But, the landlady and Sarah asked me (nicely) to remove my radials from their garden. So, I hastily errected a zig-zag dipole about 20-25 ft up between three of the trees.

Needless to say, I’ve never been real happy with the dipole. Furthermore, I only got four radials down this Fall for the inverted-L and the extras I laid on the grass sorta looked like a rat’s nest. I got to thinking…I don’t operate 160 that much. I had a rope in the pine tree at almost 60 ft for the inverted-L and I’d successfully shot a line into the big tree in the back corner to install my 40-meter dipole. I shot another line into the tree from the roof of the house. Great! I can put an 80-meter dipole at 60 feet!

The neurons kept firing…if I feed it with open wire, I can short the feeder and run it as a top-loaded vertical on 160. Brilliant. I can put the matching unit on the roof and use elevated radials (I can’t believe I’m saying this…but, it’s the only option for this installation) on 160. Dad gave me a roll of #14 THHN for Christmas (raw materials make the best presents). I went to a big box hardware store and picked-up the remaining parts for $15. I started cutting PVC pipe for spreaders with a hacksaw in the basement…hard work! Then, I remembered that the CubeSat shop is in the lab next to my office. A minute and a half with the bandsaw did what I spent a half hour on the day before. And, they looked better to boot. I built the antenna and hauled it into the trees.

Of course, using open-wire line, I had to do some matching. I measured the input impedance after the 1:1 balun (built with type-31 ferrite using a K9YC recipe) with my Autek VA-1. It’s L-network time! I figured there’s got to be an L-network calculator on the Internet that will save me a few minutes’ work. Indeed there is. I punched in the numbers and hit [calculate]. The component values seemed reasonable; so, I built it. Finding a coil form was a bit of a challenge. I have some Miniductor stock; but, nothing big enough. I tried a lot of things that I’m too sheepish to mention here before one day as I was leaving the office…I saw my coil form…lots of them piled-up against the instrument cases and cardboard boxes: poster tubes from conference travel. For good luck, I selected the three-inch tube that got stuck in the baggage handling system at O’Hare on the way home from Spring AGU in Acapulco… Actually, it gave me great pleasure to carve that up with the bandsaw.

I built the coil, added some capacitance, and triumphantly returned the relay/matching unit to the roof. I hooked-up the VA-1…and it was awful. The impedance wasn’t even close (it’s like 20-j200) to 50 ohms. I started clipping capacitors in parallel and it got worse. Then, I cut some off (the original design had three in parallel) and it’s got worse again. I’m up a creek! I went inside and had lunch. After eating, I carefully checked every joint and wire…good. So, I calculated the expected transformation given the parts. Hmmm…it gave me what I measured. I looked at the online calculator more carefully…

The calculator took the parallel equivalent circuit for the load, not the series equivalent circuit! I was in disbelief…who uses the parallel equivalent circuit unless they’re doing a calculation?! Apparently, the author did. Of course, it makes sense in retrospect…if I was writing an L-network calculator, this is the logical way to do it. I computed the parallel equivalent circuit, recalculated, and rebuilt. It hit almost dead-on 50 ohms.

It’s easy to see the lesson here: pay attention to details. But, perhaps the more important lesson is that the existence of ready-made design software does not justify ignorance of the fundamentals. Had I calculated the L-network by hand, I would have made the series-to-parallel transformation myself (or even better, let the VA-1 do it for me…wait, isn’t that how I got here?) as a part of the process. To quote the country song (out of context, of course), this was “time well-wasted.” I have a story to tell my students some day!

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Posted in education, engineering, life, radio

Five dangerous things you should let your kids do…

January 8th, 2008

I’m a huge fan of TED talks.  I could watch them all day.  This one caught my attention because I believe that it is important to explore your world, no matter how old you are.  Gever Tulley (who’s not a parent himself, ironically) lists five dangerous things that children should do…

http://www.ted.com/talks/view/id/202

My two favorites are, of course, owning a pocketknife and dissecting appliances.  This reminds me of a story…

Some friends had a “Turducken Night” party about week ago.  The party split into two groups, one to watch Battle Royale and the other to play Catchphrase.  Needless to say, we played the game.  The game needed batteries and the door was secured with two self-tapping Phillips screws.  Just as our hostess stood up, the woman to my left said, “Oh, I have batteries in my purse.”  And I produced my Letherman tool saying, “I have a screwdriver.”  The rest of the guests were astonished.  Luck favors the prepared.

Are your children prepared?

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Posted in education, engineering

Bureaucracy and Outsourcing—is it time for a new paradigm?

September 12th, 2007

I was reading E. Marla Felcher’s essay on Slate about making toys safer.  She mentions a staggering statistic on defective toys: some 76% of recalls in the past twenty years have been attributed to “design flaws.”  Perhaps toy designers should read Donald A. Norman’s The Psychology of Everyday Things.  But, the part of the essay that got my attention was her discussion of difficulty of enforcement.  This, essentially, is the difficulty with anything that is organized as a bureaucracy.

We know from high school government class that a bureaucracy is the “most efficient means to manage a large group of people.”  However, the one thing that’s not often mentioned is the characteristic of bureaucracies that gives them such a bad reputation: it’s hard to get to the bottom of things.  Multi-national corporations and militaries are built on the same bureaucratic structures.  These structures are notoriously difficult to penetrate and affect from outside—is an action criminal or just following orders?

With a bureaucracy, we have “efficiency,” but at what cost?  Perhaps outsourcing woes are a sign of things to come.  Is it time for a new paradigm?

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Posted in engineering, life

Upgrades at K8GU

July 30th, 2007

K9BF told me months ago that he had a pile of TA-33jr parts in his garage attic and that I would be welcome to dig through them. I finally had a chance to do just that a couple of weeks ago. He actually brought all of the parts over and dumped them in my garage (actually, our duplex neighbor, Ruth’s, half of the garage, since she was on vacation). It turns out that he had two essentially complete sets of elements and one boom. So, I sorted the best-looking antenna from the rest of the parts. It was time to do some refurbishing.

Mosley is somewhat (in)famous for charging an arm and a leg for replacement parts; so, I bought all of mine from McMaster.  That place has everything for the antenna-building ham!  I put the antenna up on two pieces of fence top-rail next to the garage.  As NO9Z says, “That bracket on the eves is doing all of the work.”  I have an old TR-2 “bell” rotor in the garage.  I think it might be a little too much antenna for it; but, when am I ever going to use this small of an antenna ever again?  It is fun to install an antenna by yourself, by hand.  Probably won’t be able to do that again, either.  Not like I’m complaining.

I played with the new antenna in the IARU…caught some Es on 10.  That was fun.  It’s about on-par with my groundplane on 20; although, F/B is better.  None of this is particularly surprising since it’s so low and surrounded by clutter.

After about two weeks, the landlady noticed the TA-33jr.  She seemed slightly annoyed that I hadn’t consulted her; but, didn’t seem to care that it was up there.  Note to renters:  this is a good example of shoot first and ask questions later.  Feel-out your landlord before you try this, though.

I’ve kinda had the itch to get on 160 since I got here.  I’ve been able to scratch the 160 itch once a year in the ARRL 160 with W9SZ, K9BF, and NO9Z, out at NO9Z’s.  The first year (W9SZ, 2005) that we did it, we did pretty well—it’s the first time I’ve ever had four straight 100+ hours—hard to complain about that!  Technical problems got the best of us last year (K8GU, 2006).  We’ll probably try again this year.

K9AN and I had a good discussion about wire antennas back in June that inspired me to buy a slingshot.  I was just playing around and easily launched a line over the spruce tree in our side yard.  When I realized that it was close to 60 feet up, I decided to put up an inverted-L for 160.  The DK9SQ mast was indispensible for maneuvering through tree branches.

I bought 1/4 mile of #16 aluminum for $17 at Farm and Fleet on Saturday.  I put four radials down (this is a lot of work when you’re trying to be somewhat stealthy) yesterday.  I’m going to wait until after the lawn guy comes again this week to see whether I’m doing a good job stapling it down.  Compared to the price of copper, I won’t feel too bad about leaving aluminum in the grass when we leave and it only has to last for one or two Topband “seasons.”  I figure I’ll just put a few radials in at a time until the feedpoint impedance stablizes or I get lazy, whichever happens first.

Inside, I re-routed some wiring and got rid of most of the crosstalk “hash” that I get between the TS-930’s.  NO9Z and I have most of the parts to build the KK1L antenna switches, thanks in no small part to the generosity of Ron in giving us the Gerber files for the board and K9BF for turning the Gerber files into a boards.  I still have parts for the N6BV SO2R box from ARRL Handbook sitting on my bench.  Sometime, K9SD is shipping me a dead ex-CB FT-757 to work on.  Plus, there’s some non-ham stuff there, too, like my iBook.

I also have a 160-meter SoftRock v6 kit to build.  I sold my 40/80 SoftRock v6 to KC9IKL—still not sure if that was a good idea or not. When I finally order the parts for the KK1L antenna switch from Mouser, I plan to buy some more FST3125’s to build a SoftRock interferometer (more on this at a future date).  I mentioned this idea some months back on the SMC reflector, to the great interest of at least one well-known Topbander.  It looks that VE3NEA has a version of Rocky that can do this now, too.  That man is amazing!

We acquired some “old” PC’s through surplus at work; they had SoundBlaster Live! cards in them, which, since work doesn’t require them, will form the A/D portion of the K8GU SoftRock interferometer.  The biggest problem with using these rather than an M-Audio card like the Delta-1010 is sample synchronization.  But, I’m a cheap ham…I’ll figure out how to calibrate them.

I think I’m destined to be an average contest operator with an above-average interest in the technology…

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Posted in engineering, radio

Instructables, artists, and preservation of the fundamentals

June 16th, 2007

I took the car to the shop today for its annual preventative work.  While I was waiting, I flipped through Popular Science.  Wow, that magazine has changed (for the better) over the past few years (I haven’t read it in maybe 5 years).

They have a section called “How 2.0” that has skeleton projects, some with parts lists and vendors.  Cool.  We’ve come full-circle.  It reminds me of the Instructables web site that I stumbled across a couple of years ago.  The Popular Science section is really important because it represents a mainstream publication leading to the reversal of the “Decline of the Fundamentals” described here earlier.

One of the interesting things about this is that many of the characters leading the preservation of fundamental skills are artists.  Not only are artists helping us see our world differently, they are helping us preserve valuable industrial skills.  Sounds wierd to an engineer, doesn’t it?

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Posted in education, engineering, life

The Decline of the Fundamentals

May 31st, 2007

Engineers everywhere shake their heads (or shudder) when a recent graduate new hire shows up bursting with knowledge and falls flat on their face when instructed to “do some engineering.” I oversee/mentor a few groups of seniors every semester in a Senior Design course that is intended to mitigate or avert the situation related above. So, I see a lot of painful mistakes. Many of the mistakes are things that I would consider fundamental, that is, for example, using a multimeter to measure the voltage “thru” a component rather than “across” it, or vice versa with current. (By the way, I did this once myself as a kid, before I knew Ohm’s Law and its physical meaning. I burnt-out the current measurement circuit in Dad’s meter trying to measure the voltage at a wall socket.) Short of more hands-on time in the laboratory, I began to ask myself why this was the case.

Abstraction is the concept that allows us to perform high-level tasks without understanding how the underlying process works. Technology is a fabulous example of abstraction at work. For instance, few people can really say that they understand how a computer works. I’m an EE and I have a pretty good idea of how they work; but, I wouldn’t necessarily be comfortable trying to develop a computer from scratch (at the gate or transistor level). So, this brings us back to the multimeter. At one time, the volt meter and ammeter were separate instruments; so, there was more distinction between the measurements. Is this a failure of abstraction or a failure of understanding? It does represent a fundamental failure to understand the physics: the idea that current is the flow of charge and that voltage is the potential (to do work) between charges. But, if no effort is made to stop during the education process to say, “What does this tell us about the physics?” these failures will continue. (Part of the problem is that some of the instructors have a tenuous grasp on the physics as well.) Abstraction remains an important concept, though, permitting sophistication.

The other problems are mass-production and “cheap” information. It used to be that if you wanted to get a job, you needed to know how to do something. (See The Cluetrain Manifesto for more on this sort of thing.) It is rare that one person knows and understands how an entire product is designed and constructed. This is the genius of Henry Ford and friends. It’s efficient for business, but not so good for humanity. Furthermore, we tend to let our knowledge exist in and be cataloged by Google these days. It does not occur to most of us that it might be good to own a hard copy of information that pertains to our knowledge of a product, process, or procedure. Google offers pin-point precision at the expense of “situational awareness,” understanding how the information fits into a greater context. Think of how many great discoveries may slip through the cracks of a web search!

The final culprit is assisted computation. There is a certain amount of insight gained from struggling with a mathematical expression for a physical relationship. There is even more insight in quick approximations. The art of approximation is dying. Dr Donald Milks taught my undergraduate Statics course. He was of the old school. I used to race him in solving example problems in my head using approximations. He almost always won. The few other students who were interested enough dutifully punched away on their calculators. I usually beat them, though. Dr Milks valued good hand-drawn figures, too. Indeed, the act of drawing, too, yields insight about a problem. I miss that.

Technology and abstraction allow us to solve progressively more difficult problems in science and engineering. I embrace that. However, we must take care not to lose sight of the fundamentals. For with time, the most advanced problems may prove intractable when no one understands why we want to know the answer.

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Posted in education, engineering, life

Sustainable Technology

April 15th, 2007

I’ve decided to make a more conscious effort to obtain (buy, barter, etc) used electronics. Of course, this is at odds with being an electrical engineer in some sense. But, I’ve gotten a certain amount of joy out of scrounging and repairing used radios, test equipment, and computers. Furthermore, I believe it amounts to good stewardship of time and resources.

Byproducts of the semiconductor manufacturing process are extremely hazardous. Progress has been made in recycling and minimizing waste. However, scrap devices usually contain significant quantities of lead, mercury, and other nasty stuff. There is no reason to throw this stuff out if it still serves a useful purpose.

Perhaps most important to a lifestyle of sustainable technology is the process of purchasing it. Is the new device necessary? Do I have an outlet for disposing the one it replaces? For a brief period, I was down to two computers (a notebook and a desktop). That number has blossomed to three of each. I suppose it’s time to re-evaluate this situation. (In all fairness, two of them were obtained through marriage.)

I’m satisfied with a couple of 5-10 year-old computers, 10-20 year-old ham radio gear, and 20+ year-old test equipment. I hope that even after it becomes a financial reality to replace them with brand new equipment, that I can remember to be sustainable.

(One exception to this is the inevitable day that the current AC power distribution system is outclassed by something better and more efficient. Think of the mess that’s going to cause!)

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Posted in engineering