Shortwave spy stations, still transmitting years after the Cold War

I’ve been reading a number of John Le Carré books lately, which are mostly fictional thrillers about Cold War spies. The Spy Who Came in from the Cold is a particularly good one. So in that vein, I’ve been reading about ’60s spycraft, including how they used to communicate.

In the pre-internet days, these spies used shortwave radios to receive orders from “numbers stations”, which are radio repeaters transmitting coded signals over the open airwaves, only at ranges higher than AM and FM music stations. Used together with a “one-time pad”, these encoded transmissions traveled around the world on open airwaves but were unbreakable if you didn’t have the code.

I decided to see if these “number stations” were still around, as I had heard that they are still on the air. Tech seems to go obsolete these days very quickly, so I was skeptical. Short answer, they are still broadcasting!

There’s a whole subculture of people that track these stations and there’s even a schedule that shows expected repeat transmissions. They’ve given them names based on their quirks, “The Pip”, “The Airhorn”, “The Buzzer”, all of these transmit audible sounds when inactive. When they are active, a voice reads numbers or letters from the military alphabet.

They transmit in English, Spanish, Russian, and Morse code, which gives a hint at how widely they are employed. What we don’t know is if these stations are in active use or “mothballed”, though given their level of activity, they’re at least kept in a state of readiness and have been for many years. This may be due to extreme caution on the part of spy agencies: changes in frequency of transmissions or other details might inadvertently reveal operational details. In that vein, as if a carryover from a past era, several of these transmissions are still done manually by radio operators.

Moments after I checked the page above, a station labeled “M12”, for Morse code, began transmitting: “TTT 531 531 531 TTT”. Twenty minutes later, the same message on a different “M12” channel. Who knows what this means? There’s a good chance the answer to that lies behind the former Iron Curtain.

The Cold War lives on, on shortwave radio

After reading a few too many John Le Carre spy novels, I decided to see whether the shortwave radio spies in the Cold War used is still a “thing” and whether there’s any point to buying one. I tapped into a lively nest of hobbyists and websites documenting these international airwaves online, with no need for a separate device. In short, if you have the internet and just want to play around, there’s no reason to buy a radio.

These hobbyists’ primary tool was something called a SDR or software-defined radio. The University of Twente in Enschede, Netherlands has the most famous iteration. This nifty tool is a radio that scans the airwaves and transmits constantly via a web interface. It can be used simultaneously by multiple users. It even includes a labeled waveform that shows known stations and spots of recent activity, and it can record and save audio.

I’ve spent several hours scanning the airwaves. From what I can tell, the main players are Chinese, Korean (North and South), the BBC World Service, Voice of America (VOA), and a smattering of religious channels. South Korea has a channel called “Echo of Hope”, while North Korea has “Echo of Unification” and Voice of Korea. In addition to VOA, the US government operates “Radio Free Asia” in multiple languages. Radio Taiwan International reports from Taiwan. The Chinese government reportedly jams all of the above channels from time to time . The Cuban government operates Radio Habana. Iran operates Voice of the Islamic Republic. The list goes on.

It’s like the Cold War is still being fought on the airwaves, and honestly it’s pretty boring and lo-fi. You’d be better off visiting their web presence, unless you live in a totalitarian dictatorship, in which case you’re not reading a blog in English, so I suppose a radio could be useful.
If you happen to speak Korean or Mandarin, there may be a world out there waiting to be discovered, though to be fair, both China and North Korea maintain native and English language broadcasts at different hours.

This site has a comprehensive list of stations worldwide, which you can even filter by language.