These broadcasts usually adhere to strict schedules and are spoken in a variety of languages. The toneless voices reading these messages are often female, though sometimes men’s or children’s voices are heard as well. Occasionally the transmissions contain even weirder elements, such as strange music or intonation.
Radio enthusiasts have dubbed the unexplainable broadcasts ”Number Stations”, and they have been observed at least since World War II. However, according to the Conet Project, a group that distributes recordings of these stations, the Number Stations’ transmissions have been going on since World War I. That would make them some of the oldest radio broadcasts in the world.
Despite efforts to track these broadcasts down, nobody has been able to definitively pinpoint their sources. In the few cases that a suspected site has been found, no one has been there to meet the explorers. No radio station or government has claimed responsibility for the stations, and their purpose remains uncertain. Naturally, many theories have popped up, ranging from the highly viable to the absurdly fantastical.
The most popular and likely theory is that the Number Stations are used by various Secret Services to relay orders to operatives inserted into hostile territories. With powerful enough transmitters, the coded message could be received anywhere in the world with simple equipment, and only the agent in possession of the key would be able to decrypt it. Even in today’s age of computer communications, this would be one of the most foolproof ways of communicating without leaving traces.
Some others speculate that the Number Stations are used by drug smugglers. After all, drug trafficking operations may well be organized enough to use such means.
Many of the Number Stations are likely explained by spy activity. However, some are just too weird to be unravelled quite so easily. Among them are the stations known as UVB-76 and the Backward Music Station.
UVB-76 transmits short, monotonous buzzing sounds around 25 times a minute, and it has been heard constantly, without interruption since at least 1982 – apart from certain occasions, that is. On Christmas Eve in 1997, the tone was interrupted for the first time by a Russian voice reciting names and numbers. A few similar interruptions happened on extremely rare occasions since then, until the activity suddenly picked up in 2010.
As if that wasn’t mysterious enough, it seems the buzzes are coming from something placed near a live microphone – distant conversations and other background noises can often be heard behind the tone. Despite much speculation, the purpose of UVB-76 is unknown.
The Backward Music Station broadcasts unearthly high-pitched schreeching and grinding noises, with occasional distorted voices. These signals appear to have multiple sources, with one possibly being in the US and the other in Europe. Theories include that it may be a highly encrypted message for spies, or possibly just feedback due to faulty equipment. Nevertheless, its purpose remains a mystery.
The Number Station broadcasts recorded by the Conet Project are available freely.
Image by Oroi at the German language Wikipedia