Sunday, December 02, 2007
Spies on the Radio
Clicking around on Wikipedia this weekend, I came across an article about numbers stations which I found fascinating. Turns out there are several websites, and even a Yahoo! group, devoted to this phenomenon.
Numbers stations are stations on the shortwave radio band which broadcast transmissions consisting of nothing but strings of numbers being read aloud. They first appeared on radio bands as far back as World War I, were at their highest activity during the Cold War, and have decreased in number since then. The generally held theory is that the numbers stations are used for espionage. Transmissions may also contain tones or data bursts. The transmissions may begin with music, or a set phrase to alert the listener that data transmission is about to begin. The numbers may then be decoded with one-time-use code pads, which have also been around for many years (the one-time pad was patented in 1919). This is all very low-tech, but it's reliable and it works. Interestingly, it's rare that other governments make any attempt to "jam" the stations, though it has been known to happen.
One of the best known numbers stations is the "Lincolnshire Poacher," so-called because the station uses snippets of music from a folk song by that name as an interval signal. It is thought to be operated in Cyprus by MI6, the British secret intelligence service. There is also a station that transmits messages using the phonic alphabet instead of numbers (i.e., Charlie Foxtrot Tango... etc.), which is thought to be Israeli and run by the Mossad. And there's one located in the New Mexico desert near Albuquerque, which is probably military. This station is known as "Yosemite Sam" because, oddly, the transmissions always end with a clip of the cartoon character Yosemite Sam shouting "Varmint, I'm gonna blow you to smithereens!"
If you're interested in hearing what the transmissions sound like, many of the links above have audio clips you can download; and for further reading there's an article from Wired magazine here which is quite good. Finally, if you just can't get enough of numbers stations there are even recordings for sale at this site, as well as a T shirt.
UPDATE: I found a very odd series of stories here about phone numbers, advertised on Craigslist, being used as numbers stations; fortunately it turned out to be a hacker prank. Oh, and Salon Magazine did an article about numbers stations several years ago; it's here.