Their are claims the creepy channel, which has been heard since the 1970s, could be used by spies working for Russian President Vladimir Putin.
The noise has been heard coming from frequency 4625 kHz, and is usually just a buzzing sound.
However, there are occasional code words and numbers read out in a Russian accent.
All else that is know so far is that the transmission appears to originate from a remote swampland near St Petersburg.
No one has tracked down who is behind the baffling broadcast known as “The Buzzer”, or “MDZhB”.
Other theories are that it is connected to secret research on aliens, the Russian military, or other secretive government projects.
Anyone around the world can tune into the station.
One wild theory is that it is a “Dead Man’s Switch” system to launch nuclear bombs from Russia in the event the country had already been anhilated.
The first recording of the alleged station was made in 1982.
Professor David Stupples, an expert in signals intelligence from City University, London, said: “There’s absolutely no information in the signal.”
He said the noise has changed slightly over the years, but has always involved some form of regular buzzing, interrupted by a voice occasionally apparently reading out a message.
One theory is the station is used by the Russian army to detect how far away missiles are.
Professor Stupples said: “To get good results from the radar systems the Russians use to spot missiles, you need to know this.”
Yet, does not believe this is the explanation, since waves needed for this type of detection would sound more like a “car alarm” than buzzer.
One conspiracy theory is that the Buzzer is used to instruct a global network of Russian spies.
The theory suggests the code words and numbers are encrypted, so they cannot be deciphered by anyone else, but transmit instructions to the spies.
It has been suggested Russia may use the station during an national emergency to instruct spies and military personal across the globe.
Maris Goldmanis, a radio enthusiast who regularly listens to the station, believes he heard it tested.
He said: “In 2013 they issued a special message, “COMMAND 135 ISSUED” that was said to be test message for full combat readiness.”
However, Professor Stupples added: “If this phone call were encrypted you’d hear ‘…enejekdhejenw…’ but then it would come out the other side sounding like normal speech.”
He said encryption would leave traces in the sound that are not there.
The signal is a “shortwave”, and operates at a relatively low frequency which allows it to cover vast distances.
As an open channel MDZhB prevents stops people working out exactly where it is broadcast from.
One mundane theory is the buzz could simply be a marker – a way to stop other people from using the frequency.
However, currently there has been no definitive explanation and the mystery buzzes on.