A Great Way to Listen to Those Mysterious "Number Stations"

Illustration for article titled A Great Way to Listen to Those Mysterious Number Stations

For decades, shortwave radio enthusiasts have been stumbling upon mysterious stations that broadcast a looping noise, such as a nursery rhyme, occasionally punctuated by someone reading a string of numbers. The most popular theory is that these are coded messages—and now, an online shortwave radio lets you listen in.

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Shortwave is an ideal medium for transmitting messages to spies and the military, notes the blog War is Boring. It's easy to broadcast globally, hard to trace and free of commercial traffic.

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The theory is that spies or military personnel tune into the frequency at an appointed time and use a one-time pad to decrypt the message. Anyone else listening hears a random string of numbers with no context.

The University of Twente in the Netherlands maintains a web-based shortwave radio that anyone can access. War is Boring recommends its two favorite "numbers stations":

The Buzzer: Tune the dial to 4625 kHz and you'll hear a repetitive buzzing noise. This obnoxious station goes by the call sign UVB-76, but shortwave aficionados call it The Buzzer. The Buzzer has been blaring that tone since the early 1980s. On occasion, the buzzing stops. A voice comes on and reads numbers and letters in Russian.

Yosemite Sam: The cranky gunslinger from old Bugs Bunny cartoons began screaming across the shortwave band around 2004. He's hard to pinpoint because he moves. But you can typically find him at 3700 kHz or 6500 kHz.

Every broadcast begins with a millisecond-long compressed data burst followed by a sound clip of Yosemite Sam. The data burst and sound clip then moves to a higher frequency. This broadcast is repeated over a two minute period before receding back into the darkness. To date, no one has decoded the data burst.

While it's tempting to think of these stations as relics of the Cold War, pitifully broadcasting recordings of numbers like the radio tower in Lost, recent history suggests otherwise:

In the late 1990s, the FBI busted a group of Cuban spies known as the Wasp's Network. The five Cuban intelligence officers received messages from back home via a shortwave radio station transmitting numbers. The coded messages were a large part of the FBI's court case.

It was the only time a government publicly acknowledged the existence and purpose of the numbers stations.

So remember as you're listening to the repetitive buzz out of Russia or a woman reading numbers in a foreign language … these messages are meant for someone. You aren't the only one listening.

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[Source: War is Boring]

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DISCUSSION

Reader's guide for French poetry majors: shortwave radio uses frequencies between about 10 and 40 MHz to communicate directly point-to-point by reflecting signals off the ionosphere. The advantage is that no relay station or satellite is needed. The ionosphere is a natural layer of charged particles about 50-200 miles above the earth, created by solar radiation. This charged layer reflects signals back to earth that would otherwise stream out into space. Shortwave broadcasting was a very big deal up until the advent of the internet; it still exists but is in decline.

Early radio systems used very long wavelength signals, sometimes 20,000 meters or longer. Such signals tend to hug the earth's surface, and for a while it was thought that longer wavelengths gave longer range. Radio amateurs were relegated to wavelengths shorter than 200 meters, thought to be useless. However, they found that short wavelengths around 30 meters gave very long ranges under some circumstances, and "shortwave" was born. It was later determined that this was due to ionospheric reflection, called "skywave". Radio amateurs still use these frequencies today, and communicate via skywave all the time.