Atencion! Tres, uno, cinco…

Most of us have used a radio reciever to listen to music, news, and entertainment programming. Worldwide, there are broadcasters keeping the airwaves alive 24 hours a day, and there’s almost never a lack of anything to listen to in the AM and FM broadcast bands.

Somewhere between, notably, in the area between 3 and 30 Mhz, there’s a strange parallel world of signals. In that band, known as shortwave or HF (High Frequency), the radio waves are reflected off the Earth’s surface and ionosphere, allowing them to sometimes travel all the way around the world.

Occasionally, a distant station will be heard with a strange echo as it is recieved first from a rather direct bounce off the ionosphere, followed by a bounce that went all the way around the globe!

As for the content of these signals, just about anything can be found on shortwave; news and music from your own country and others around the world, ham radio operators and captains of ships and aircraft speaking to each other, and any number of digital signals carrying everything from text to weather charts. Morse Code, still quite alive and well, continues to be used there worldwide.

Explore the world of shortwave radio long enough, though, and you will run into one of radio’s oldest mysteries. Among the static, ionospheric whistes, lightning crashes, man-made electrical noise, and other background radiation, voices, Morse code, and electronic tones send out mysterious messages consisting only of numbers.

There are any number of theories as to the intent, originator, and recipients of these messages, and quite a large number of different transmission formats which would suggest different organizations as their sources. Some of them are known to have been used to send encrypted messages to spies in the field, some may be messages destined for foreign embassies, and there are rumors that some are even used by drug smugglers and terrorists. The only thing that is certain is that only one organization knows the meaning of these messages, and they aren’t sharing.

A typical transmission from one of these stations consists of two parts; a preamble, and a message. The preamble is a call-up with a distinctive sound and content, intended to allow the station’s recipient to easily find the signal by ear. This is necessary as the station may need to change frequency due to interference or jamming, or the recipient in the field may be limited to using very simple and inconspicuous radio equipment that doesn’t have a well calibrated tuning indicator.

These call-up sequences are quite intentionally unique, and are sometimes very interesting. Musical sequences, repeated call signs in voice or Morse code, and electronic tones have all been used by various stations. Listeners worldwide have heard everything from repeated callsigns or simple beeps to musical pieces by Jean-Michel Jarre preceding messages.

One of the most well remembered of these would come on the air with a snake charmer-like flute melody, to which a voice repeated the words “Papa November”, over and over. Well, in case you were wondering what inspired the odd title of this site, there you go…

A couple of stations even have interval signals that run continuously. One, known as ‘The Squeaky Wheel’, sent a squeaking set of tones every few seconds for several years before pausing temporarily for a voice to read out numbers. Other similarly repetitive beeps or ticks may be similar operations.

The messages themselves are generally numbers grouped into blocks of 5 digits, which are deciphered using either a written code book or by computer software. The means by which they are sent varies by the station; some use synthesized or recorded and replayed voices, some use manually or automatically sent Morse code, and some use digital codes. One of the creepiest sounding stations uses an electronic polytone system, in which a tone is assigned to each number from 0 to 9, and they are sent sequentially at about 3 digits per second.

Much has been speculated, observed, and written about these stations, but the only way to experience the truly mysterious, magical, and downright chillingly creepy phenomenon that they are is to listen in. These stations are located all over the world, and there may even be some practically right in your backyard. I’ve actually found a few in my hometown of Miami!

Here are some links for further information:
The Enigma 2000 group, dedicated to the study and observation of these strange creatures., with some information and schedules
Stations that may be on the air now, or in the next hour
Simon Mason’s site
A recording of a Cuban numbers station. This one’s rather famous for its poor transmission quality and technical glitches. Birds have even been heard squawking over the woman reading numbers over the horrendous AC hum over the Morse code leaking in from another transmission over the Morse code leaking in from yet another transmission. (*phew*)

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