Tag Archives: Numbers Station

Podcast dives into world of Cold War Numbers Stations

Cold War number stations

You might remember listening to short wave radio during the Cold War and coming across weird transmissions of metallic voices reciting random groups of numbers through the ether. These are number stations, shortwave radio stations characterised by broadcasts of formatted numbers, which were being sent to spies operating in foreign countries.

Number stations were used widely during the Cold War and we speak with Jo Reggelt of ShortwaveNumbers.com. Jo has been working with Simon Mason who was a founding member of ENIGMA, launched in the 1980’s after identifying several of these stations.

We discuss in detail the operations behind the transmissions and the stations themselves. You will hear some sample transmissions, including one of drunken Stasi officers serenading their agents after the opening of the Wall. [Continue reading…]

Click here to listen to this podcast on the Cold War Conversations website,
or via iTunes or Spotify.

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Operator shares what it’s like to work for a numbers station

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(Source: Numbers Stations)

Working at a numbers station 6 decades ago was not much different than working at an AM broadcast station. Located on a WWII old Naval Base it consisted of one building surrounded by a double chain link fence inside which older local men drove pickup trucks around for security. Inside the building there was a workshop, two 20,000-watt AM shortwave transmitters, crystal controlled oscillators, and a soundproof booth with a record player and records of well-known music in a language and culture common to the target. Outside the compound was an antenna farm with a log periodic antenna, a rhombic, and a couple dipoles.

I lived, with my wife, about a mile from the site and would drive through a back road to the location, be admitted by security through each gate, and park, and relieve the other op who, after briefing me, was free to go home. My job was to follow a schedule, select the proper frequency at the proper time, tune the transmitter, hit the plate voltage, play the record the schedule told me to, and then recite the messages arranged in five-number groups of numbers in the appropriate language into the microphone in the recording booth. This was all done live and, as far as I know, no recordings were kept.

[…]Other than that it’s just a job. The messages were all prepared somewhere else by someone else and delivered to us along with the schedule. We all had high level clearances but we never knew who we sent these to or what the real ones might have said. This sort of compartmentalization was (and is) common.

I often thought of those for whom the messages were intended… how they felt, where they were… whether they were in an attic or shed or stranded somewhere copying down a message that was a threat to their very lives on a radio that was a death penalty to simply be in possession of. I was very careful to do it right.[…]

Read the full article at Numbers-Stations.com.

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Was Morse Code the smoking gun for this spy with no name?

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Many thanks to SWLing Post contributor, Dan Robinson, who shares this story from the BBC News via Matthew M. Aid‘s blog:

[…]It was a cold Saturday morning in April 1988 when a van full of detectives arrived outside the North London home of Erwin van Haarlem. The self-employed art dealer, 44, lived alone in sleepy Friern Barnet, a smattering of brick homes beside the grim North Circular ring road.
The Dutchman’s apartment building on Silver Birch Close had become the centre of an investigation led by the British intelligence agency MI5. It suspected that Van Haarlem – whom neighbours described as an “oddball” – was not in the art business at all, but a sinister foreign agent.

Inside, Van Haarlem was hunched over a radio in his kitchen. He was still wearing his pyjamas, but his hair was parted neatly to one side. He was tuned in, as he was every morning, to a mysterious “number station”. In his earpiece, a female voice recited numbers in Czech, followed by the blip-bleep of Morse code.

At 09:15 detectives from Special Branch, the anti-terror unit of London’s Metropolitan Police, crashed into his apartment. Van Haarlem tried to lower his radio’s antenna. It jammed. When he pulled open a drawer and grabbed a kitchen knife, an officer tackled him, and yelled: “Enough! It is over! It is over!”

Hidden among his easels and paintings, detectives discovered tiny codebooks concealed in a bar of soap, strange chemicals, and car magazines later found to contain messages written in invisible ink. Investigators suspected Van Haarlem was not really from the Netherlands, but was a spy for the UK’s Cold War adversary, the Soviet Union.

[…]Mrs Saint, 61, who co-ordinated the local Neighbourhood Watch Scheme, said she telephoned the police in November 1987 to report strange noises and a “Morse code” interference which affected her television reception every night at 21:20.[…]

Click here to read this fascinating in0depth story on the BBC Magazine website.

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Pavel’s 70s era recording of a German numbers station

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I read this account Pavel posted on the Spooks reflector and asked if he would share his story on the SWLing Post. He kindly agreed.

Pavel writes:

“Inspired by a recent thread about a vintage number station, I searched my old tapes (I really [have a] LOT of them, hundreds of reels, mostly with music, but sometimes with other interesting things) and finally found a short snippet of a German number station transmission. There is neither a start nor end of the transmission, just a few 5-digit groups. It was recorded sometime between 1977 – 1980, at my cottage near Ceska Lipa, Czech Republic (but it was Czechoslovak Socialistic Republic [then]).

Reception was made on a Czechoslovak tube receiver “Barcarola” on a shortwave band with classic AM (of course this receiver was not capable of SSB or any other advanced modes) using a random wire (about 10 m) antenna.

A recording was made on the B400 Czechoslovak tape recorder using a Scotch 220 magnetic tape (exactly the one which is in the picture), speed 9.53 cm/s. Import to the digital domain was performed using the Audacity open source sound recording and processing software, without any artificial filtering or other DSP techniques.

As you can hear, it was perfect, clear readability:

I know that because the recording is incomplete, it has just a low value as such, but maybe it can at least demonstrate, which kind of equipment was obvious at this time and that it was possible to use it for activities like SW listening and number station (at least the strong ones) monitoring.

I’m curious whether somebody will identify the station.

With regards,
Pavel

Pavel’s Barcarola was similar to this model (Photo source: http://www.oldradio.cz/)

What really amazes me is the fidelity of Pavel’s recording. Though the transmitter might have been relatively local, there is certainly something to be said for analog equipment–both Pavel’s Barcarola receiver and his B400 recorder.

I actually collect and maintain more tube receivers than solid state. While their sensitivity and selectivity isn’t always on par with modern receivers, their warm audio fidelity makes up for it.

If you can identify Pavel’s numbers station recording, please comment.

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Cuban Numbers Station HM01: serving up a little confusion

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On occasion, I hear the Cuban numbers station HM01 on 5,855 kHz on weekday mornings.

It seems that many of the mornings as I listen, I hear HM01 making mistakes or at least experiencing “technical difficulties” (click here for a recent case in point).

Though I don’t often record HM01, I did record it on the morning of September 20, 2013––and, yet again, I heard what seemed to be HM01 tripping over its own tongue.

Instead of the broadcast starting with numbers to identify the transmission, then implementing intermittent RDFT data bursts as per usual, this broadcast begins in the middle of a data burst, then shuffles awkwardly into a “normal” broadcast. I imagine an operative in the field scratching his or her head…

But hear this for yourself. Either click here to download an MP3 of the recording, or simply listen via the embedded player below:

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Shortwave Radio Recordings: Listen to Cuban Spy Numbers Station HM01

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Numbers stations have always been a dark oddity that pop up from time-to-time in the course of shortwave radio listening. There is unquestionably an air of mystery and intrigue which surrounds them. With the release of the movie The Numbers Station, many non-SWLers may be enticed to explore the HF bands. A good thing, as it may draw fresh interest to this classic radio hobby.

I have heard numbers stations since I first started listening to shortwave radio broadcasts some thirty years ago, and I find that I often pause to listen (and to wonder) when I come across one on the bands. The numbers station I hear most often, though the country of origin cannot be confirmed, is in Cuba–well, at least, we’re pretty certain of that. The same female voice, reading numbers in Spanish, has been Cuba’s calling card in the spy numbers world for some time.

Two weeks ago, on a Sunday morning between 10:00-11:00 UTC, I captured the Cuban spy numbers station widely recognized as HM01 (Hybrid Mode Number 01) on 5,855 kHz. HM01 broadcasts a mixture of AM voice and digital file transfer modes intermixed within the same transmission. The voice heard is the familiar Spanish female voice described above; the digital portion of the broadcast uses a mode called RDFT, a differential phase shift keying mode that has never become popular or standard in the ham radio world. If you’re feeling adventurous, the Windows software DIGTRX (download here) can decode RDFT. Let us know what, if anything, you discover…

You can click here to download the entire HM01 broadcast as an MP3, or simply listen via the embedded player below:

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