Signals and Spies
A supposedly obsolete technology is being used to air cryptic riddles
There’s a perception the shortwave radio spectrum is a staticky remnant of analog communications history. Regular readers know I’m fond of supposedly obsolete technology. Bouncing amplitude modulated signals off the ionosphere still has value in emergencies and reaching people — who due to geography, poverty or government decree — have limited or no access to digital information.
That is why I ensured that our limited-run weekly one-hour program, America@250: Due Diligence, which many listen to as an online podcast, not only airs on FM radio (including WRCT in Pittsburgh), but also on dozens of AM stations, as well as the most powerful shortwave radio broadcaster in the United States, WRMI, as a service of Radio Free America. Our fifth episode will run this weekend and more on that here on Saturday.
My career in journalism and broadcasting in no small part stems from my avocation as a shortwave listener and then a licensed amateur radio operator (currently W7DQ).
Back in the day, the airwaves between 10 and 160 meters were filled with distant signals, many enrolled in an ideological battle. There were the propaganda stations behind the Iron Curtain, the popular talk and music programs targeting Asia and Africa on Deutsche Welle, Radio Ceylon, RFE/RL and VOA; pirate stations in international waters playing rock music banned on the BBC; time and frequency markers; air traffic control for trans-oceanic flights; radar pulses (such as the infamous Russian ‘woodpecker,’ designed to detect over-the-horizon ballistic middle launches); clandestine stations in the jungles trying to overthrow governments or offering an alternative to repressive state-control media.
There were also, of course, the ham radio signals (the sideband voices sounding like Donald Duck on AM radios). The most tantalizing transmissions were the “numbers stations.” These mysterious broadcasts, voiced or in Morse code, were clearly in the realm of military intelligence or espionage. MI6 had the ‘Lincolnshire Poacher,’ Cuba’s DGI ran ‘Atencion.’ Moscow still sounds the ‘Buzzer’ (Жужжалка), which is always on 4625 kHz.
In one of my ham radio online chat groups on Wednesday, (the Long Island CW Club, of which I’m an honorary life member), a fellow amateur in Canada, Chris, whose call sign is VE3RWJ, notes his interception of a prolific numbers station about which there is a modicum of reliable information. The station has a legitimate call sign 4XZ (not to be confused with a rap musician using the same moniker).
4XZ (the station, not the rapper) is operated by the Israeli navy out of Haifa and sends Morse code (CW or continuous wave) transmissions around the clock, simultaneously on several frequencies.
Monitors report 4XZ delivers as many as 900 messages monthly, consisting of five-letter groups with a dozen or so new messages daily but more when naval exercises take place. It previously would also broadcast weather bulletins. Monitors note that each item of the traffic list consists of the recipient call sign (letter, letter, digit, letter), the message number, a two-letter code of unknown purpose and the group count. All digit sequences in 4XZ are written in reverse order (Hebrew is written right-to-left).
Chris in Canada, an accomplished CW operator and active member of the Blind Hams Digital Net, writes about his interception of 4XZ sending test messages on 10 mHz, which even a novice in radio communications knows is a terrible choice because that’s the frequency used continuously by time signal stations WWV (Colorado) and WWVH (Hawaii), operated by the National Institute of Standards and Technology (NIST), part of the Department of Commerce. To put it succinctly, an Israeli military radio station appears to be causing worldwide interference to a U.S. government radio station.
Chris noticed the 4XZ transmission does not appear to be automated, but rather the Morse Code is being tapped out by a sloppy telegrapher.
“Anyone know why the sending is lopsided? Is that a (semi-automatic) bug? A straight key? I’m curious to know why the code isn’t more even,” Chris asks.
These numbers stations are deliberately low key, so to speak, as they exist in a shadowy world. Sending sloppy CW on top of two of the world’s most recognized shortwaves stations (WWV and WWVH) is not a clandestine action. Is this a deliberate provocation? A rogue corporal messing around or accidentally running a test on the wrong frequency? Another possibility — a mischievous imposter trying to dupe us into believing it’s the Israelis.
These kind of mysteries excited me as a young shortwave listener and they are still intriguing decades later.