Category Archives: Articles

Bill helps with low-power, license-free broadcasting

In reference to our post, Dave’s FM Station Empire, SWLing Post reader Bill writes:

Nice article on the use of low power broadcasting. For the last 5 years my site, HobbyBroadcaster.net, has been helping radio enthusiasts along with schools and businesses learn how to use legal, low power, license-free Part 15 radio for a variety of uses. I created the site due to my involvement with starting a campus-limited high school station and discovering the lack of quality resources available for school-based broadcasters unable to obtain an FCC allocation. With many hobbyists also using this same technology on AM to serve their neighbors with micro radio it only seemed natural to expand the interest to hobbyists, too.

Also, Part 15 regulations allow for some use of the shortwave bands for experimental broadcasting with the most common frequency used by hobbyists being 13.56 MHz.

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How to decode that RDFT in numbers station HM01? Roland explains

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A few weeks ago, I published a post with a recording of the Cuban numbers station HM01, a “Hybrid Mode” numbers station which interchangeably broadcasts both voice and a digital mode called RDFT with each transmission. I had suggested using an application called “DIGTRX” to decode the data bursts.

I then received a comment on that post from the author of the DIGTRX program himself, Roland. He has actually created a page in English which describes in detail how to decode the RDFT in HM01. Note that this page was originally in Roland’s native Portugese, and he kindly translates it into English for us: http://www.qsl.net/py4zbz/eni.htm

[While this means that we can decode the transmissions, it doesn’t mean we can necessarily decipher them, however. At least, not yet.]

Imagine that a spy numbers station is using an application you, yourself, authored to send coded messages. What are the odds? This apparently happened to Roland, when he discovered that HM01 was, in fact, using his application DIGTRX. What?!?

Actually, it makes sense to me that numbers stations would use DIGTRX. After all, it’s open source. Operatives in the field can download the application without raising awareness. If it were a proprietary application, either commercially or of their own design, it would add to the complication of downloading and using it (on both ends). As you’ll read in Roland’s tutorial, HM01 has built in robust redundancies by using RDFT and DIGTRX. Very interesting.

Thanks, Roland, for sharing!

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China appears to be jamming the BBC World Service (and the SWLing Post)

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Structure of a Denial of Service attack. (Image: WikiMedia Commons)

No doubt, in publishing this, The SWLing Post will be hit with another barrage of denial-of-service attacks. If you notice the site loading slowly, or completely off-line for periods of time in the near future, you’ll know why…

A few weeks ago I mentioned various upgrades to the SWLing Post web server. Part of this is due to our increased traffic and part is due to the fact that we were moving to a more secure server.

You see, recently I posted an article with a recording of Firedrake along with a follow-up from Post reader, Mark. Two days later, The SWLing Post was hit with denial-of-service attacks from IP addresses, all of which appeared to originate from China. It almost brought the whole server down–however, my intrepid web host, CloudWeb, scrambled to block the offenders, and they did an amazing job. You may note that I had to temporarily remove the Firedrake posts (they’ve since been re-published). I don’t consider this to be a conciliation, but rather a victory: for free speech, and for its power on shortwave radio.

Anyone who follows the SWLing Post with regularity will know that I’m a strong believer in access to and freedom of news and information, so I’m a bit annoyed by the DoS attacks that attempt, however unsuccessfully, to mute our voice in China and throughout the world. No doubt, The SWLing Post is already behind the “great” firewall, anyway.

If our site does go down, follow our updates on Twitter and Facebook.

With that preamble behind me, I owe my thanks to Andy Sennitt for bringing this article to my attention:

Reuters-Logo1 (Source: Reuters)

Radio broadcasts in English from the BBC World Service are being jammed in China, the British broadcaster said on Monday, suggesting the Chinese authorities were behind the disruption.

“The BBC strongly condemns this action which is designed to disrupt audiences’ free access to news and information,” the BBC said in a statement.

China, which enforces strict restrictions on its domestic media, has been accused by several prominent foreign media of seeking to stop their news reports reaching Chinese audiences.

“The BBC has received reports that World Service English shortwave frequencies are being jammed in China,” said the London-based public service broadcaster.

“Though it is not possible at this stage to attribute the source of the jamming definitively, the extensive and coordinated efforts are indicative of a well-resourced country such as China.”

A duty officer at China’s foreign ministry had no immediate comment.

[…]”The jamming of shortwave transmissions is being timed to cause maximum disruption to BBC World Service English broadcasts in China,” said Peter Horrocks, director of BBC Global News.

“The deliberate and coordinated efforts by authorities in countries such as China and Iran illustrate the significance and importance of the role the BBC undertakes to provide impartial and accurate information to audiences around the world.”[…]

Click here to read the full article by Estelle Shirbon; with additional reporting by Lucy Hornby; Editing by Tom Pfeiffer at Reuters.com

For more stories like this, follow our tag: Why Shortwave Radio?

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Numbers stations: stranger than fiction

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towers More mentions of numbers stations in the popular press, thanks to the new movie, The Numbers Station. Hat tip to SWLing Post reader, HK:

(Source: Reelz.com)

[…]If you ever find yourself wishing your life was filled with a little more mystery, a little more excitement, save up thirty dollars and go buy a shortwave radio and start scanning the airwaves. With a little luck and a lot of patience, you might come across a band carrying the monotone voice of a man reciting military call letters (“Echo — Kilo — Charlie”), the robotic voice of a woman counting in Russian, or one broadcasting a continual string of beeps, chirps or hums. If you manage to tune in to one of these stations, you could very well be listening in on a coded message intended for a spy.

Once thought to be useless for communications purposes because of their high frequencies and short wavelengths, shortwave radio bands were, it was discovered in the 1920’s, ideal for sending messages over extremely long distances. Shortwave signals are broadcast into the sky, where they are reflected or refracted off of the electrically-charged ionosphere layer of the upper atmoshpere and sent back down to Earth as far as a continent away. By the start of the Cold War a few decades later, countless shortwave radio stations were found to be broadcasting strange, seemingly coded, messages using this technique. At the time, these so-called “number stations” (or “numbers stations”) were widely believed to be in use by various government intelligence agencies to broadcast secret messages to spies over great distances, but none of the codes — if, indeed, that’s what the signals were — were ever cracked and no governments ever officially acknowledged their use.

Number stations remained a mystery and were all but forgotten by the general public until the discovery in the ’70s of a station that was broadcasting a powerful signal comprised of the synthesized voice of a British woman speaking a sequence of five numbers. The station came to be known as “The Lincolnshire Poacher” because two bars from the English folk song of that name served as interval signals. The signal from the station was traced back to the Royal Air Force base at Akrotiri, on the island of Cyprus, providing number station enthusiasts with the first “proof” that government organizations like the British Secret Intelligence Service were behind some, if not most, of the number stations.[…]

Read the full article at Reelz.com. Keep track of news on numbers stations and our recordings by following the numbers stations category.

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VOA’s Radiogram adds digital content to AM broadcasts

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VOA Radiogram is a new Voice of America program experimenting with digital text and images via AM shortwave broadcasting. One might say this is the crossover point between classic shortwave and current technology. It’s fun and fascinating stuff, and also has real utility.

If you’ve been an SWLing Post reader for very long, you’ll be familiar with the digital messages, otherwise known as radiograms, included in broadcasts from The Mighty KBC and, earlier, from WBCQ. We’ve also offered a small primer on decoding.

In the near future, Dr. Kim Elliott’s digital radiograms will be broadcast through VOA via the Edward R. Murrow Transmission Station in Greenville, NC.

The new VOA Radiogram website contains time and frequencies and all of the information you’ll need to decode VOA radiograms.

Incidentally, Kim Elliott and I will be presenting on the topic of VOA Radiograms and digital modes at the 2013 NASWA Winter SWL Fest. If you’re interested, it’s not too late to register! Meanwhile, stay tuned for more information about radiograms.

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Trevor Baylis in the Vintage Vault

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Earlier this week, I posted an article about wind-up (clockwork) radio inventor, Trevor Baylis.

I recently discovered a 1995 episode of RNW’s Media Network, which featured Baylis–and the clockwork radio–in the context of inventions that would carry us beyond the new millenium:

(Source: Media Network Vintage Vault)

Remember Trevor Baylis and the wind-up radio? I organised a conference for Radio Netherlands at the International Broadcasting Convention IBC between September 11-14th 1995. We decided to celebrate the fact that we were 5 years away from a new Millennium by looking at the technologies that would carry us forward. That included a look at different codings for DAB, a reality check on radio by Sri Lankan broadcaster Victor Goonetilleke and a special performance about the Clockwork Radio from Trevor Baylis, the British inventor who turned up in Amsterdam and charmed the audience with his frank, funny and brilliant introduction to the concept of wind-up radios. A few weeks after the conference we produced a special CD for those who took part. This is a copy for those who missed it. It’s double the length of a normal Media Network, just over an hour.

You can download this archive episode of Media Network on the Vintage Vault website.

By the way, Jonathan Mark’s Media Network Vintage Vault has many, many audio treasures from the radio past. Certainly worth bookmarking!

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History of WWV and the NIST Time Stations

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WWV building in Fort Collins, Colorado (photo courtesy: NIST)

Many readers know that I’m a bit of a WWV geek, so you can imagine how happy I was when my buddy, Mike, and the Southgate ARC made me aware of this 152 page history of the NIST time station family. At first glance, this looks to be an authoritative and thorough history indeed.

I have already sent this to my Kindle Fire and look forward to reading it (at least, starting it) tonight. Click here to download the NIST time station history as a PDF.

Incidentally, if you have an affinity for the NIST time stations, be sure to check out my previous post on Myke’s audio history of WWV, “At The Tone.”

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