TUNING IN (PDF)
The Weirder Side Of Wireless
With Mumbled Directions Home
If, like a rolling stone, you find yourself skittering clueless down an unknown road, it just may be because Bob Dylan is guiding you home. According to a report in the Washington Post, among other sources, Dylan said on his BBC satellite radio program, Theme Time Radio Hour, that two carmakers have expressed an interest in borrowing (I guess “renting” is a better choice) the famous raspy-mumbly voice. Rumor has it he’s negotiating with two car manufacturers to be the voice of their in-car navigation systems.
Personally, I’ve always only been able to understand about every third
word of the once-counter-culture figure, and am not sure I’d want to put
in the effort required to decipher his instructions for high-speed
merging. Dylan didn’t put such anxiety to rest by giving a teaser of his
guiding ability on his radio show, previewing his would-be GPS vocals
with, “Left at the next street. No, right. You know what? Just go
straight.” Subsequent reports from a number of sources have said that
Dylan meant it as a joke. We’ll see. Be on the lookout for cars having
trouble with high-speed merges.
A Bulgarian radio station was fined for running a pre-recorded message from Madonna, inviting fans to her concert in Sofia, Bulgaria’s capital. The problem was not with her music, clothing, or controversial projects and behavior, but that she used English to record the message. Bulgaria’s Council for Electronic Media slapped Darik Radio with a large fine for airing Madonna’s English invitation, according to the Bulgarian daily, 24 Chasa and The Sofia Echo website. Apparently chapter 12 article 1 of the Radio and Television Act states that all advertisements in foreign languages are forbidden, so the commission ordered Darik Radio to pay a penalty in the range of 2000 to 15000 leva (approximately US $1,445–10,838). A repeat of the offending broadcast would have doubled the fine. The 10-second message from Madonna to her fans in Bulgaria said: “Hello Bulgaria, this is Madonna and I expect to see you at the August 29 show in Sofia in Vassil Levsli Stadium.”
The Sofia Echo stated that a spokesperson for Sofia Music Enterprises, the
Bulgarian organizers of Madonna’s concert, said “this is normal procedure
and it is used in all countries. Any time Madonna has a concert in a
country, she records a message for her fans, and it is always in English.
There is no way that an exception will be made just for us.” Konstantin
Vulkov, program manager of Darik Radio said the station “apologizes that
Madonna is not proficient in Bulgarian,” according to The Sofia Echo
News, Trends, And Short Takes
by D. Prabakaran
RFI Signs Mobile Broadcast Deal For Five U.S. Cities
Radio France International has signed an agreement with mobile phone
broadcaster AudioNow to broadcast its French programs on the telephone
network, 24 hours a day, in five US cities. Listeners in Boston, Chicago,
San Francisco, Miami, and New York will be able to hear RFI on their
cellphones by calling the following phone numbers (only local charges will
apply): 617-963-1545 (Boston), 312-646-7684 (Chicago), 415-200-0603 (San
Francisco), 786-228-5543 (Miami), and in New York City (number not
provided at press time).
The website of the BBC Russian service (bbcrussian.com) launched an
archive of significant historical radio programs from the past 45 years.
Among the voices featured in the audio archive are Alexander Kerensky,
Prime Minister during the 1917 Russian Revolution; Nobel Laureates for
Literature Alexander Solzhenitsyn and Joseph Brodsky; one of Russia’s
great poets Anna Akhmatova; and Stalin’s daughter Svetlana Alliluyeva. It
also features former British Prime Minister Margaret Thatcher, and former
Beatle Paul McCartney, both of whom took part in live phone-ins with
audiences in the USSR in the Eighties. The archive can be accessed through
the radio page at www.bbcrussian.com
Taliban insurgents fighting Afghan and international troops based in
Afghanistan have established their propaganda mouthpiece in the southern
Ghazni province, locals said. The FM transmitter, according to locals,
airs programs from 7 p.m. until 9 p.m. (1430–1630 UTC) local time and
often broadcasts Taliban anti-government propaganda in Pashtu. It has
identified itself as Da Shariat Ghag Radio, or Radio voice of Sharia
(Islamic Laws) and has been airing programs on Taliban anti-government
activities, according to one local. Da Shariat Ghag Radio was the official
mouthpiece of Taliban regime before its collapse in late 2001. Taliban
purported spokesman Zabihullah Mujahid told media from an undisclosed
location via telephone that militants have established four radio stations
in the country.
Capitol Hill And FCC Actions Affecting Communications
by Richard Fisher, KI6SN
FCC Takes Plunge Into Social Networking And Blogging
In an effort to achieve an “open and participatory process,” the Federal Communications Commission took a technological leap in mid-August when it created its identity on the social networking site Twitter and started an Internet blog focusing on the National Broadband Plan.
Twitter allows users to post text-based messages of up to 140 characters displayed on the originator’s profile page and delivered to site subscribers. In its infancy, the Commission’s Twitter page had already attracted almost 2,000 followers. The site can be found at http://twitter.com/fccdotgov.
The FCC has also started an Internet blog called “Blogband,” focusing on the National Broadband Plan. It can be accessed at http://blog.broadband. gov/. “Like our unprecedented two-dozen public workshops and the (scheduled) public hearings, Blogband is part of the FCC’s commitment to an open and participatory process,” FCC Chairman Julius Genachowski said in Blogband’s inaugural posting. The information “will keep people up-to-date about the work the FCC is doing and the progress we’re making. But we want it to be a two-way conversation.”
Genachowski pointed out that in the Commission’s opinion, the “National
Broadband Plan is one of the most important initiatives that the FCC has
ever undertaken…What better time to start blogging than now?...we need as
many people involved as possible.”
“The notice in the August 11, 2009 Federal Register, entitled ‘Assessment
and Collection of Regulatory Fees for Fiscal Year 2009,’ includes
regulatory fees; these fees are expected to recover a total of
$341,875,000 during FY2009, encompassing all the services the FCC
regulates,” the ARRL reported.
by Rob de Santos
Back in the early ’80s, the singer/songwriter Sting wrote lyrics, “There’s a little black spot on the sun today. It’s the same old thing as yesterday.” Has it been a while since you had that experience? For many readers I suspect it’s your private kingdom of pain under current solar conditions.
One of the facts of life for every shortwave listener and ham of my generation concerns the sunspot cycle: Once you had any experience in the hobby, you just knew that as sunspots increase, the propagation improves (or changes), and as they wane, reception worsens, and then the cycle repeats. Except when it doesn’t. Few readers of this magazine will not be aware of how slow the upside of this new solar cycle seems to be.
But what if the sunspots don’t return? Or at least, they return in such small numbers we never have a normal “peak” to the solar cycle, then what? The implications for the communications business are significant and not just in a hobby sense. Sunspot levels affect far more than just the reception of Radio Australia in my bedroom. Let’s consider just a few of the ways that might change communications:
Satellite lifetimes: Orbits don’t decay as quickly when solar activity is lower, and the risk of damage to sensitive electronics is reduced when there are fewer solar storms. This would mean satellites wouldn’t have to be replaced as quickly and it would reduce the decay rate of their orbits. This would affect everything from television relays to the lifetime of amateur radio’s “OSCAR” satellites.
Weather. This is a big gray area. We know that the sun impacts our
terrestrial weather and longer-term climatic conditions. The problem is we
don’t know just how much. Past periods with low sunspot numbers over
decades corresponded to cooler worldwide temperatures. It’s hard to say
how, when combined with “global warming” this would change communications
habits around the globe.
The Technology Of Modern Rebellion
Text Messaging And Twitter Vs. Repressive Regimes
By Kirk A. Kleinschmidt, NTØZ
As everyday people in ordinary neighborhoods, across the 50 states and from continent to continent, strive to better themselves, raise their children, and go about their daily lives, the world they live has been growing ever smaller. Over the past 100 years the relentless march of technology—radio, electronics, computers, the Internet, and telecommunications—familiar to Pop’Comm readers, has been a blessing to society as a whole, but a curse to individuals, corporations, and governments with “things to hide” or opposing issues to suppress.
From celebrities frolicking on a secluded South Pacific beach (snap!—the
paparazzo’s digital photo is uploaded to a Hollywood tell-all Internet
tabloid via cell phone or sat phone and, in less than three minutes, is
online for everyone to see); to cell phone video of the hanging of former
Iraqi dictator Saddam Hussein (which even the U.S. wanted to suppress) and
the murder, on June 20, 2009, allegedly by Iranian government agents, of
26-year-old Neda Agha-Soltani, a young Iranian woman who was shot dead as
she stepped out of her car in Tehran near the site of an anti-government
protest (the graphic and unedited cell phone video of Soltani’s last
moments spread like wildfire on the Internet and global TV news shows and
became a rallying event for Iranians protesting the questionable election
victory of President Mahmoud Ahmadinejad); it’s almost impossible to
suppress information and events in the modern era of entrenched
Although this article primarily focuses on the tools and techniques used by the citizens and the government of Iran during the events associated with the country’s contested presidential election in the summer of 2009, the discussion is relevant to many events in many other countries, including Iraq, Afghanistan, Myanmar, China, and even the U.S. and other “developed” nations—and it will likely become even more relevant in the near future.
Although Iranian citizens enjoy certain “democracy-like” freedoms and educational opportunities not necessarily enjoyed by other Islamic republics in the region, Iranian citizens—especially an ever-more-strident youthful demographic—had grown increasingly unhappy with the country’s elected and theocratic leaders.
This general unrest came to a head in the summer of 2009 when, from mid-June through early August, tens of thousands of people (probably more) protested in the streets of Tehran and several other major Iranian cities in support of opposition candidate Mir-Hossein Mousavi.
Amid widespread protests and allegations of massive voter fraud, Ayatollah Ali Khamenei, Iran’s religious leader and behind-the-scenes political power broker, declared that President Mahmoud Ahmadinejad had won a decisive reelection victory and that the election’s dramatic result was a “divine assessment.”
Outside Iran’s inner political circle the divine assessment seemed all too
profane. Many citizens and all of the opposition presidential candidates,
including Mousavi, claimed that the election was manipulated and that the
results were rigged. Although foreign election monitors were generally not
allowed to keep an eye on things inside Iran, most outside observers side
with the Iranian opposition in noting “electoral irregularities.” The
protests that followed have been called “The Green Revolution” (playing on
Mousavi’s green campaign colors) and “The Persian Awakening.”
Exploring The World On A Radio DXpedition
by Bruce A. Conti
Since the famed 1991 Newfoundland DXpedition celebrating the 90-year anniversary of the historic first Marconi transatlantic wireless communication, the DXpedition has become an integral part of AM broadcast band (or mediumwave) long-distance listening (DXing).
Here in the Northern Hemisphere, November is considered one of the best months for DXpeditions, so we dedicate this month to all who have braved carrying suspicious radio gear through airport security, erecting antennas over rough terrain in foul weather, and explaining the CIA-like activity to innkeepers, curious passers by, and sometimes local law enforcement.
Such are the risks we DXpeditioners take to catch an elusive signal, add a
country to the logbook, or receive signals that could never be heard at
home. Five representative DXpeditions out of many solo and group sessions
held over the past year have been chosen to try to capture the DXcitement.
Narratives of the DXpeditioners are followed by selected logs. All times
Many a DXer has dreamed of a South African radio safari. The southern tip of Africa is an outstanding region for DXpeditioning due to Atlantic and Indian Ocean saltwater paths. Fortunately for those of us unable to make the long journey to such an exotic locale, we can still enjoy the experience through DXers lucky enough to live in this radio active part of the world. The following report and logs come from South African resident Graham Bell who describes a solo DXpedition:
I spent a couple of nights at Elands Cottage in the Cape Point Reserve,
south of Cape Town. It’s a comfortable cottage with lots of space around
(for antennas). I put out two Beverage-On-Ground (BOG) antennas, one of
250-m at 310 degrees and another of 320-m at 320 degrees. I also had a
shorter 80-m longwire pointing to magnetic north. Though the two BOG
antennas were on a very similar bearing but of differing lengths, I can’t
say either one was systematically better than the other (front, back or
null). What I found was that it was useful to have the option to switch
from one to the other to fine tune the incoming signal. In some cases they
gave very different results. I used both my Drake R8 and NRD-545. The
Drake hasn’t had many outings in recent years so it was a good chance to
be reminded of what a good receiver it is, especially in the quiet
conditions we enjoy in these parts. Highlights were a fair signal from
XEPE San Diego, two Philippines stations and “local” stations Emissora
Provincial de Bengo, Angola and Radio Benue, Makurdi, Nigeria. The AM dial
used to be peppered with Angolans, Cameroonians, and Nigerians but there
aren’t many left. These two came in with really fine signals and audio
with interesting local programming, especially Makurdi.
New, Interesting, And Useful Communications Products
MFJ Enters Scanner Market With Two New Offerings
MFJ has entered the scanner market with two new product introductions: the MFJ-8310 Base Scanner, which receives NOAA, police/fire/ham repeaters; and the MFJ-8322 Analog Trunking Scanner, a handheld model that also tunes 800-MHz public service bands and analog Motorola (type I, II and hybrid), EDACS Wide and LTR trunked systems.
The MFJ-8310 scanner monitors 2-meter, 70-cm, 10-meter and 6-meter repeaters plus repeater inputs and local simplex frequencies, NOAA weather broadcasts, weather alerts, SKYWARN, VHF and UHF business bands, commercial aircraft, marine band, FRS/GMRS frequencies and more. During severe weather, its one-touch weather button takes the place of expensive single-purpose weather radio; another one-touch button monitors SKYWARN trained weather observers (requires one-time programming). It features a BNC antenna connection; backlit LCD and 3-inch speaker; front panel on/off switch with separate volume and squelch controls; and 3.5-mm headset jack for private listening. It includes pull-up BNC antenna and 120 VAC-to-9 VDC adapter.
The MFJ-8322 is a triple-trunking handheld scanner with alpha display that lets you easily program talkgroup IDs. Covering all the UHF and VHF bands, it offers the same features as the MFJ-8310 base scanner and adds the 222–225 MHz ham band, military aircraft frequencies, and the 1240–1300 MHz ham band. It stores up to 1,000 frequencies, a maximum of 10 trunked systems and up to 1,500 total TIDs. A Spectrum Sweeper mode offers remarkable sensitivity and rapidly searches for local transmitters of unknown frequency, finding, tuning, and monitoring a nearby transmission in roughly 3/4 of a second, or you can lock out undesired frequencies and search again.
Other features include PC programming capability (the MFJ-5432 Scanner USB cable connects the scanner to your PC; $29.95) and BNC antenna connector. It also comes with a flex antenna and AC adapter charger (requires four AA Alkaline or NiMH batteries; NiMH charge automatically to full charge in the scanner when the adapter/charger is attached), on/off/volume control and squelch control, and 3.5-mm headset jack.
The MFJ-8322 retails for $199.95; the MFJ-8310 for $99.95. For additional
information, to order, get a free catalog, or for your nearest dealer,
contact MFJ Enterprises, 300 Industrial Park Road, Starkville, MS 39759;
Phone: 800-647-1800; Web: www.mfjenterprises.com.
THE PRACTICAL SIDE
The Antenna Room
TV Antenna Basics
by Kent Britain, WA5VJB
I’ve often enjoyed reading the TV channel history of a city just by
looking at the rooftops as I drove though the neighborhoods. By
understanding the different antenna designs, like the one in Photo A, you
can tell what channels the people wanted to watch over the decades. Well,
so much for history…now onto modern times, like why a good understanding
of TV antennas is handy when you need to put one up. Let’s take it from
the beginning, with television frequency ranges, as follows:
We start with the three main U.S. Bands for TV transmitters. TV Channels 2 to 6, 7 to 13 and 14 to 51. On most antennas there are elements designed to resonate in each of these three frequency bands. The antenna can then be used just about anywhere to watch any channel.
Let’s take a look at the conical, sometimes called bi-conical, TV antenna in Figure 1. When hams used them they were called “wonder bar” antennas, and if you see one of these in the air, you’ll know that it’s been there for half a century. They’re pretty good on VHF Lo, and the short elements in the middle are for VHF Hi. When these were first designed, the UHF band wasn’t even around. My first ham 6-meter antenna was one of these, but I extended each element about 6 inches. Hey, I worked eight states on 6-meter AM with it! It also worked well on TV Channel 1, but more on that at the end of the column.
Now we move on to the typical herringbone TV antenna in Photo B. About 40 years ago it was discovered that if you swept the log periodic antenna elements forward at about a 30-degree angle, the log periodic worked well on its third harmonic. So if the log periodic on the left in this figure were designed to cover 50–100 MHz, then the log periodic on the right would work on 50–100 MHz and 150–300 MHz. The third harmonic of 56–88 MHz is 168–264 MHz and covers the 170–216 MHz VHF Hi band nicely. A swept forward log periodic, therefore, can easily cover both VHF Lo and VHF Hi at the same time, and that’s why so many outdoor TV antennas use this basic design. On the front you see the UHF elements which we’ll cover a bit more in a moment.
Three elements in the herringbone log periodic is about the smallest you
can make work on both VHF Lo and VHF Hi. But there is no upper limit on
this antenna: As you add more elements, gain and size goes up. About a
dozen VHF Lo elements is the practical limit and that would be nearly 30
feet long. (One of those “round-to-it” projects on my work bench is a
140–170 MHz herringbone log periodic to cover 140–170 MHz and 420–500 MHz
for both the scanner and ham crowds in one antenna.)
THE INTERSECTION OF
COMPUTERS AND RADIO
Internet Radio Roundup: A Sampling From The WiFi Scene
by Dan Srebnick, K2DLS
Ever since Real Audio hit the scene in 1995, I’ve been intrigued by online “DX” possibilities. I started out listening to a lot of Dutch domestic stations that simulcast on the Internet (the Dutch were early adopters of Internet radio). The World Radio Network (wrn.org) offered the opportunity to listen to international broadcasters such as Radio Nederland and the BBC. Early listening sessions consisted of 16 kpbs streams over a 28.8 kbps dialup. Windows 3.1 crashed a lot, making online listening sometimes as much of a challenge as “real DX.”
A lot has changed. Today, broadband Internet connections are common in
many households. Windows is stable, and Mac OS/X and Linux all offer media
players to tune into Internet media content. But the biggest change over
the past couple of years is that a computer is not needed to listen to
radio via the Internet. Today, we have “WiFi radio.”
The major differentiator between the different models of WiFi radio are
the chipsets. The chipset includes firmware that provides the radio’s
operating system. The operating system determines the “personality” of the
device, defines its features and how you interact with it. While it sounds
a lot like a computer, the similarity ends here as there is no keyboard,
mouse, or hard disk involved.
The major WiFi radio platforms fall into the following categories:
Many different manufacturers offer Reciva- and vTuner-based radios.
Logitech (<www.logitech.com>) and Phoenix (<www.com-one.biz>) also have proprietary
offerings with full feature sets, and Phoenix seems to have recently added
Real Audio, so choose carefully. Each vendor has a website that allows the
listener to create lists of their favorite stations and, in some cases,
playlists. Let’s take a look at some of the available choices.
Lessons Learned From The “October Surprise”—Simple Preparedness Steps You Can Take
by John Kasupski, KC2HMZ
This month I’m going to do a bit of reminiscing about a severe winter weather event that took place in Buffalo, New York, roughly three years ago, in October 2006, with an eye toward relating what can be learned from the standpoint of EmComm and preparedness.
Even if you don’t live in an area that is prone to winter storms, the lessons from one disaster are as good as the lessons from the next. While you may not get serious snow or ice, chances are (unfortunately) good that there’s some sort of natural or man-made disaster you might be subjected to. The results are often similar regardless of the nature of the event: disruption of food and water supplies and communications; interruption of utility service; travel difficult or impossible…the list goes on. How do you prepare for it?
The so-called “October Surprise” of 2006 was an unusual early-season lake
effect snowstorm that hit Buffalo and the surrounding area in the U.S. and
Canada. It began in the afternoon on October 12, and didn’t end until the
morning of the next day. It became known as the October surprise because
in Buffalo autumn weather is typically just beginning then. The leaves on
the trees were just beginning to turn brilliant colors and boats were
still moving along the Erie Canal and the Niagara River. Snow blowers were
still stored in garages, their fuel tanks empty. The water temperature in
Lake Erie was 62 degrees Fahrenheit. The lake effect storms capable of
producing feet—not inches—of snow in just a few hours were still (we
thought!) several weeks away at least.
Like most disasters, the October Surprise happened unexpectedly; and yet, it shouldn’t have come as a surprise at all. The first concerns of a possible “Lake Effect Snow Event” were raised on October 6 as medium- and long-range numerical weather models began to indicate conditions would be potentially favorable for lake effect precipitation, resulting in mixed snow-rain conditions. The long-term forecast from the Buffalo office of the National Weather Service indicated possible lake effect snows, but predicted that accumulations would be minimal.
By October 11, the Buffalo NWS and associated weather offices in the U.S and Canada began issuing special advisories for the possibility of lake effect snows, which mentioned that since the leaves were still on the trees, the combination of snow and wet leaves on trees could cause branches or trees to fall, bringing down power lines and resulting in widespread power outages. That’s exactly what happened, starting the following afternoon.
The first notable ground accumulations started to occur just before 5 p.m., and by 8 p.m., reports of downed trees and power lines and other damage began to flood the NWS offices (see Photos A and B). Schools were closed for a week. Telephone lines were still down weeks later. Thirteen people died. The damage was the worst of any storm in Buffalo’s history.
THE PRACTICAL SIDE
The Propagation Corner
A Sunspot Puzzle
by Tomas Hood
Something is unusual about the current sunspot cycle. The current solar minimum has been unusually long, and with more than 700 days without sunspots through August 2009, the number of spotless days has not been equaled since 1933 (see <http://users.telenet.be/j.janssens/ Spotless/Spotless.html>). The solar wind is reported to be in a uniquely low energy state since space measurements began nearly 40 years ago. This solar minimum has become a real puzzle to solar scientists who are working diligently to understand what exactly is happening with our sun.
There’s an obvious interest in a lack of
sunspots from the perspective of radio hobbyists because solar activity as
measured by sunspot counts correlates to the strength of the ionosphere.
Without an energized ionosphere, shortwave signals won’t reach around the
world. There are other reasons, too, for an interest in this uniquely
quiet solar minimum.
Sunspots are magnetic regions on the sun with magnetic field strengths thousands of times stronger than the Earth’s magnetic field. Plasma flows in the sun’s magnetic field lines (Figure 1), and sunspots appear as dark spots on its surface. Temperatures in the dark centers of sunspots, the “umbra,” drop to about 3700 K, compared to 5700 K for the surrounding photosphere. It’s this difference in temperatures that makes the spots appear darker than elsewhere.
Sunspots usually form in groups containing two sets of spots. One set will have a positive or north magnetic field while the other set will have a negative or south magnetic field. The magnetic field is strongest in the darker parts of the sunspot; the field is weaker and more horizontal in the lighter part, the “penumbra” (Figure 2).
Since the time of Galileo Galilea, who made
the first European observations of sunspots in 1610, observers and
scientists have discovered a great deal about the sun and its influence on
the Earth and our atmosphere. The Chinese and many other early
civilizations were the first to discover sunspots. Daily sunspot
observations were started at the Zurich Observatory in 1749, and by 1849
continuous sunspot observations were recorded. Over time, cycles in solar
activity were revealed. The sun’s sunspot activity has a cycle that lasts
for an approximate 11-year period. The cycle starts with very quiet solar
activity with very few sunspots, then peaks about three to five years
later with a very high number of daily sunspots, and then decreases in
sunspot activity until the end of the solar cycle.
Shannon’s Broadcast Classics
by Shannon Huniwell
When my neighbor Melissa heard the news on her kitchen radio, time rushed backwards. She quickly connected the story’s dots and suddenly saw herself in Seattle’s North City School again. A memory crystallized.
Standing there clear as day in her mind’s eye, Melissa’s fourth grade teacher, Mrs. Aguayo, had just explained to the class that they’d be putting messages in soda bottles, and a friend with a boat would toss them onto waves of Puget Sound. Mrs. Aguayo said some could travel to distant shores and predicted that a few might even be found by curious people who’d be happy to respond to the enclosed letter offering a snapshot of the sender if the finder notified the school by mail.
That 1987 science project related to geography lessons and an elementary study of ocean currents netted one response—21 years and 1,735 miles later. “Merle Brandell and his black lab, Slapsey, were beach-combing along the Bering Sea,” the announcer broadcasting Associated Press news copy (from March 23, 2008) informed his audience, “when he spied a plastic bottle...along the shore of his tiny remote western Alaskan fishing village.” Inside the weathered container was the typed form letter signed by a classmate Melissa couldn’t picture.
According to the AP, Brandell wrote to Seattle’s Shoreline School District and a helpful official there tracked down the girl who’d sent the message, “now a 30-year-old accountant...who lives in Seattle. ‘I don’t remember the project,’ she told reporters. ‘It was so long ago. Elementary school is kind of foggy.’”
Melissa’s recollections of the bottle-message project are vivid compared to those of the young woman quoted on the radio. Like my Dad, Melissa’s father is a longtime DXer. Consequently, he had instilled in her a love of sending away for free stuff from radio stations. “Envisioning the little plastic bottle sailing my letter to some exotic port of call,” she said, smiling, “I guess was kind of like taking a fun chance that something even more interesting might come my way.”
Her experience in the DXing hobby taught her
the truth of the maxim that you have to give in order to receive. “It was
always a thrill to hop off the school bus in the afternoon, run to our
mailbox, and see what resulted from reception reports Dad had helped me
fire off a few weeks earlier,” Melissa remembered. “My wish was to get a
little visual piece of the station I’d heard sail through the air.
Whenever the return address sported a station logo, I felt like I’d won
THE PRACTICAL SIDE
The Wireless Connection
AC Voltmeters For Dummies
by Peter J.
I once commented that a diode wired in series in an AC circuit would reduce the power by one half, not the voltage. That is counter intuitive to what you would think at first, but it makes sense once you consider that the duty cycle—and thus the power—has been reduced by 50 percent. That works out to about 0.707 times the RMS voltage, or 81.3 volts for a 115 VAC line voltage.
I was surprised to receive several very adamant admonishments insisting that I was wrong. The truth is that anyone using a typical True RMS voltmeter, which is an AC coupled device, would be misled by a reading that is actually closer to one half the applied voltage than the times 0.707 calculation that is correct for half power. This is most unfortunate, and I believe in doing test bench experiments to verify that things are as they appear. But I found it even odder that the few who complained never bothered to run the math using the power formulas to prove their point, one way or the other.
I believe that when well-intended experiments lead to erroneous conclusions, it is time to act! But I’m getting ahead of myself…
Let’s begin by discussing the ins-and-outs of AC voltmeters. There are plenty of reference books that delve into the mathematics; but I’d rather take a few editorial liberties to keep things simple for those folks who are not engineers or technicians.
Remember that an AC waveform is dynamic and is
constantly changing amplitude with time. To determine the power contained
in that waveform, the voltage is averaged to a corresponding reading that
represents the same energy that would be delivered by a steady-state DC
voltage. That AC voltage is the root mean square (RMS) voltage. We should
be pretty much agreement that we need accurate AC voltage readings to use
the power formulas or Ohms Law.
Vintage, inexpensive shop meters were simple devices, and they assumed that the voltages being measured would most likely be a pure sinewave that was related to the AC line voltage. The AC voltage being measured is rectified in the meter and is really displayed as a DC voltage. The AC meter scales indicate the average of the AC voltage being measured. If the voltage is a sinewave, then the average is the correct RMS voltage; if not, all bets are off.
Often manufacturers included an additional scale for peak AC voltage. There was no magic there; those scales were simply 1.414 times higher than the AC meter scale. If you need to calculate the peak voltage of true sinewave AC voltage, which is the peak voltage at the peak of the waveform crest, simply multiply the RMS reading by 1.414 to find the answer.
I’d bet many readers own a bench meter similar
to the basic Heathkit model IM-13 vacuum tube voltmeter shown in Photo A.
I built the kit in junior high school and it has served me well. It’s an
averaging-type AC meter, with the inherent limitations mentioned above. It
is also very representative of the sort of meter used in radio shops since
Utility Communications Digest
Decoding MIL-STD-188-110A With MultiPSK In Test Stages
by John Kasupski, KC2HMZ
Users of the popular multimode digital communications program MultiPSK received some good news this August when the author, Patrick Lindecker, F6CTE, announced that he’s working on adding the ability to send and receive MIL-STD-188-110A, also known by its NATO designation STANAG 4539 and the civilian government designation FED-STD-1052, to the professional version of the program. Lindecker also released a test version of the program with the new function included.
MIL-STD-188 (Military Standard 188) is a
series of telecommunications standards in use by U.S. military forces and
government stations as well as those of several allied countries, and is
also reportedly being used by the Chinese military. When first developed,
MIL-STD-188 covered technical standards for tactical and long-haul
communications, but subsequent revisions produced three series of
subdivided documents, one of which is the current MIL-STD-188-100.
Lindecker told Pop’Comm “at the moment it is just a test version. I’m beaconing 75 bps 110A just now.” He added that he hoped to have the “official” MultiPSK v4.15 ready in early September, with the 110A function included.
Now, of course, military and government stations do not produce MIL-STD-188-100 using software packages such as MultiPSK—they do so using radios that are designed to operate using the protocols specified by the standards, such as the Harris AN/PRC-152 (Photo A). For the curious—or those who just hate acronyms—the A and N stand for Army and Navy; PRC stands for Portable Radio Communications. However, such radios, as well as hardware-based packages sold for ham and hobby use, are priced well beyond the means of the average utility listener. The addition of MIL-STD-188-110A to MultiPSK makes this program an affordable and cost-effective alternative for digital decoding, especially since the program also already supports ALE decoding.
It’s important to note this since MultiPSK
exists in two forms: a free version and a professional version. The
capability to decode 110A will only be available in the professional
version, currently priced at 30 Euros or $45.00 U.S. That’s still a lot
less expensive than the available alternatives, especially with Skysweeper
having been discontinued in June.
It’s been a while since we updated you on
upcoming NASA mission launches. There’s one launch scheduled for this
month and two for December. Those of you who enjoy listening to NASA comms
during these launches will want to make a note of them.
THE LIGHTER SIDE
Trivia And Toons
by R.B. Sturtevant, AD7IL
Q. After World War II the Japanese took over most of the electronics manufacturing in the world. What were their wartime electronics like? Did this give them the springboard to take off in the field?
A. No it definitely didn’t. Their wartime electronics industry was way behind ours. The most advanced area of Japanese electronics was sonar, and it seems they got a lot of help from the Germans. They also never got around to putting the technology to the utmost advantage by developing attack capabilities using their sonar. They had no airborne radar in production at the end of the war, and their ground radar didn’t show up until 1942, even then it was a copy of German, British, and American designs. Their radio and radio direction finding equipment lagged behind as well.
Japanese training methods were also quite conventional and handicapped by the lack of technical background and electronics knowledge among the general populace. Later, faced with shorter training courses toward the end of the war, technical staff had to specialize in just one piece of equipment rather than several. Even their wire was judged substandard, probably a supply problem brought on by lack of supplies due to shipping problems.
How did the Japanese gain such a predominance
after the war? They closely observed the American GIs and their
electronics, learning everything they could. The man who would later head
Sony Corporation was running a fix-it shop in Tokyo when a GI brought in a
tape recorder for repair. The repairman had never seen one but took the
job anyway. When he got inside he said “I can build one of these
things”—and the rest is history.
THE LIGHTER SIDE
The Loose Connection
Radio vs. Gardening: Bill Slam-dunks A Zucchini
by Bill Price, N3AVY
I’m sure there are people who look at radio amateurs and shortwave listeners and wonder what could possibly be the attraction. I know there are hobbies that leave me wondering the same thing. Probably the worst of all is gardening. How in the name of Hiram Percy Maxim could anyone enjoy doing the kind of work we typically hire illegal aliens to do for us because it’s a job that no American wants to do?
They may laugh at us for spinning a dial and listening to static and beeps and foreign languages and hams who talk like ducks, but it has to be better than driving to some place and spending money for a dozen clumps of dirt in plastic containers with some wisps of weed-like things sticking up from the dirt, then driving home and crawling in the dirt, digging and rearranging the mud and neatly arranging these little weeds in rows in the dirt, and pouring little bags of expensive dirt over them, then going into the house and washing up and watching television for a week until you can go out and notice that something has happened to your little weeds.
Imagine if we had to turn on our radios and tune a station then go and wait and watch television for a week to see if any sounds came out of the speaker!
Gardeners sometimes have it even worse! Sometimes they start with seeds! They dig and turn and churn and hoe and hum and loosen up all that mud, then stick some seeds into the ground, then go into the house and wash up and smear some foul-smelling menthol muscle rub all over their aching bodies and watch television for a week until they can go out and notice that some tiny green stem is sticking out of the ground where they planted their seeds. Zowie! What fun! These little green things don’t even send QSL cards!
I realize that we in the radio hobbies have
sunspots, which sometimes limit our activity on some bands, and at some
distances, but in general, there’s never been a time when we can’t find
some interesting signals on some bands at any hour of the day or night.