They're Taking the Guesswork out of Scatter Communications

As with many areas of electronics communications, much of both the initial and continued research in atmospheric scattering of electromagnetic signals was/is done by amateur radio operators. The phenomenon is routinely used for accomplishing long distance communications (DX, in Ham terms) by exploiting the reflection property of ionized layers when radio signals impinge at a certain angle. The portion of the signal that returns to the transmitter location, when monitored, can provide information to the sender about the height, distance, and frequency range of the reflecting atmospheric layer. Some of the first indications of backscattering were noticed by radar operators who would receive echo returns from "phantom" targets that were really atmospheric reflections...

Bell Telephone Laboratories Advertisement - Crystal Timekeeping

I don't know about you, but I really miss the hard-wired POTS (Plain Ordinary Telephone System) days of remote communications. Unless the conversation was with an overseas telco system, there was never a noticeable delay where both parties were constantly either "stepping" on each other's words or having to consciously wait before speaking to make sure the other guy has finished. Whether it be cellphone-to-cellphone or cellphone-to-VoIP, nearly every conversation is annoying. Sometimes when one party is on the POTS line with either a cell or Internet connection it can go well, but if you want a hassle-free conversation (assuming the person you're talking to is not a PiTA), you need a hard-wired connection on both ends. People loved to hate Bell Telephone back in the day...

Time for Another Breakthrough

Amateur radio operators - and all electromagnetic spectrum users for that matter - have always lamented crowded bands and interference (QRM and QRN). That goes for licensed and unlicensed bands. In 1976 when this editorial was printed in the ARRL's QST magazine, spectrum occupation within allocated bands was defined by commonplace analog AM and FM methods. Co-existence was generally not possible for operation within a common frequency range. Spread spectrum modulation / demodulation changed all that beginning in the 1990s, but prior to then such schemes were largely the exclusive domain of military communications, as were many other spectrum-saving methods which are commonplace today. A big part of the reason is the significant advances in digital processing hardware and software, along with declassification of some of the algorithms that eventually found their way into cellphone, WiFi, and other commercial applications. Given that many of the professional engineers...

SPURS Software - RF Design Magazine Software Contest

Way...... back in 1992, RF Design magazine ran a software contest. Those were the days when most engineers and hobbyists wrote software in either Basic or Fortran. I happened to use Turbo Pascal, by Borland. At the time, I was working as an RF engineer for Comsat, in Germantown, MD. Having done a lot of frequency conversion designs in my previous work at General Electric, and even more there at Comsat, I had already written a crude program to calculate mixer spurious products, so this challenge gave me the excuse I needed to refine the user interface and add some creature comfort features like loadable mixer spur files and detection of spectral inversion if present. Although I did not win the grand prize, I did win the runner-up prize (along with, I think, a couple other people). The prizes included having the following article published...

Radio Engineering Crossword Puzzle for July 26th

July 26th's custom Radio Engineering crossword puzzle contains some words particular to radio, radar, analog and digital circuits, components, and other tech-themed words and clues. Each week for two decades I have created a new technology-themed crossword puzzle using only words (1,000s of them) from my custom-created lexicon related to engineering, science, mathematics, chemistry, physics, astronomy, etc. You will never find among the words names of politicians, mountain ranges, exotic foods or plants, movie stars, or anything of the sort. You might, however, find someone or something in the otherwise excluded list directly related to this puzzle's technology theme, such as Hedy Lamarr or the Bikini Atoll, respectively. Avid cruciverbalists amongst us: the gauntlet has been thrown down.

Facts About Military Electronics Training and Subsequent Civilian Employment

To be honest, I don't know whether military electronics training commands the respect in private industry that it did back in 1982 when I separated from the U.S. Air Force. If you left the military within the last 20 years or so and care to share your experience with seeking civilian employment, I'll be glad to add it here as a side note. Many of the electronics technicians I worked with both as a tech myself and then as an engineer (after earning a BSEE) got their initial classroom training in either the Air Force or the Navy. There were probably some from the Marines and Army, but I don't recall any off-hand. I hate to admit it, but I think the Navy vets were even more highly sought after than we Air Force types. This 1969 issue of Electronics Illustrated...

Crossword Puzzle - Electronics & Other Things

Cruciverbalists rejoice! Here is another tech-related crossword puzzle to try your technical prowess. Unlike the weekly RF Cafe crossword puzzle that contains only engineering, science, mathematics and other tech words, this one from Electronics World does have a few unrelated words. The big difference between making crosswords then and now is Mrs. Le Fevre had to construct the grid of words manually, whereas I just create a huge file of words and definitions, draw the grid outline, and then click a button to have software put it all together. I'm guessing it took a couple hours to make this puzzle...

Radio Terms Illustrated

These "Radio Term Illustrated" comics from vintage Radio-Craft magazines are some of my favorite tech-themed comics. Most were drawn by Frank Beaven in response to suggestions / requests by magazine readers. The one here from page 80 entitled "Crystal Gazing" was done by Franklin Folger. If you didn't know that it appeared in a 1947 edition, you might assume it depicts a Steam Punk themed LCD computer monitor mounted atop a Morse code straight key, but of course it is not. At the time, cathode ray tubes (CRTs) were the only form of video display, and while small like the one in the drawing (and round, unlike the drawing), they were far from flat. Little did the artist suspect that his "Crystal Gazing" idea meant to imply a type of mystic's medium for seeing...

Mac's Radio Service Shop: A Little Lightning

Benjamin Franklin is famous for his kite-flying experiment whereby he 'discovered' not electricity (as many people believe), but that lightning is a form of electricity (most people thought it was a jet of gas). A lesser known fact about Mr. Franklin is that he invented the lightning rod after realizing the electrical nature of lightning. His understanding of electric fields facilitated an implementation whereby hefty iron cabling interconnected a tall, pointed rod installed at the tallest point on a building and a spike driven into the ground. Lightning typically strikes the object that is the shortest distance (in terms of electrical field strength) from it because the discharge can begin at the lowest voltage. The presence of the grounded lightning rod above the highest point on a structure effectively brings that point all the way down to ground level...

Powder Puff Derby

Prior to seeing this new tidbit in a 1976 issue of QST magazine, I had no idea that the wife of Peanuts comic strip creator Charles Schulz was an airplane pilot - and that is with having been a huge Peanuts fan for decades. Other than one of Snoopy's alter egos being that of a World War I flying ace, there is no other theme of airplanes in the strip, although according to this article, there was a 1975 Sunday comic strip with Peppermint Patty and Marcie flying atop Snoopy's doghouse, from California to Michigan. The Straits Area Radio Club (W8GQN) provided communications for the Powder Puff Derby, aka the Women's Air Derby, race in which Mrs. Jean Clyde Schulz took part in 1970, 1971, and 1975. It was a very long course - more than 2,000 miles as the crow flies...

Negative Feedback Transistor Amplifiers

The big graphic with Figures 1 through 17 reminds me of the kinds of study sheets I used to make when cramming for exams in my college circuits courses. Did I ever tell you about the wise guy instructor I had for my first Circuits class at the University of Vermont? Anyway, this article provides an introductory level treatment of using negative feedback in amplifier circuits. Lots of illustration and formulas are included. Frequencies are at baseband, so you won't learn any secrets for high frequency amplifier stabilization, but then even RF and microwave circuits eventually need to convert down to baseband at some point for sampling or for use as audio or video...

Measuring Semiconductor Device Input Parameters with Vector Analysis

Joe Cahak, owner of Sunshine Design Engineering Services in Ramona, California, has written a white paper entitled, "Measuring Semiconductor Device Input Parameters with Vector Analysis." This article covers a recent test experience that utilized some thinking about the test fixture, the bias requirements and the device mounting and special calibration offsets needed to de-embed the test fixture response from the device response within the test fixture. The device also had to have bias on several ports simultaneously. We had to establish a "reference plane" within the fixture, from which we can use the Vector Network Analyzer's Port Extension or Phase Offset to dial out the distance from our 1 port calibration reference plane to the point of short reference within the fixture. With this phase offset compensation we can then measure...

What Does Your Daily Commute Cost You?

How far do you commute each day for the privilege of doing your part to push back the frontiers of technical ignorance and to boldly go where no engineer - or technician - has gone before. Do you know what the cost equates for you each year? This handy-dandy infographic lays out some gruesome numbers. Those with a weak stomach probably should pass on viewing this one. Here's a hint at what you will see: See that big $795 in the thumbnail image? That's the average cost per year for commuting -- per mile! Yessiree, if you live just 10 miles from work, you're losing nearly $8,000 per year, depending on you automobile type, on gas, tires, maintenance, devaluation, and loss of your personal time (which is valuable, after all). Back in the early 1990s I drove about 45 miles each way...