If you’re a shortwave radio enthusiast, or if you’ve had the chance to travel through Russia, then you may have heard one of three strangest radio stations ever known to man: UVB-76 (The Buzzer), 5448/3756 kHz (The Pip), and 3828/5473 (The Squeaky Wheel). Now, as much as these names might sound like normal nicknames that the stations adopted because they’re easier to remember than their numbers, these are actually names given to them due to the sounds they broadcast. You see, these radio stations are named for the bizarre sounds that they emit—a buzzer, a beep, and a siren-type sound, respectively.

Little is known about these mysterious radio stations other than that they are based in Russia and are believed to move from time to time. UVB-76 is the best known of the three stations because it is believed to have been in operation since at least 1973, when the transmissions began getting picked up in the West. Shortwave radio listeners were amazed to hear the constant buzzers and beeps of the stations, even more so when these monotonous sounds were interrupted.

The Pip and The Squeaky Wheel sometimes broadcast what sounds like coded messages in Russian.

Listeners of The Buzzer have also picked up what sounded like phone conversations in Russian from possibly unaware technicians in the studio.

Most familiar with the radio stations believe that they are all connected, but it’s anyone’s guess as to what their purposes are. Although the Iron Curtain officially came down in 1991, the Russian government has not been forthcoming about these mysterious stations.

Most believe that the stations are somehow connected to the military, but their functions are anyone’s guess. Some think that they served as an archaic form of communication during the Cold War and are now obsolete but were never shut down due to inefficiencies in the Russian bureaucracy. One of the more ominous explanations is that they are part of the Soviet Era “Dead Hand” system. The Dead Hand system was developed by the Soviet Union during the Cold War to counter America’s first strike capabilities. Because the Americans had more sophisticated weapons and were capable of destroying much of the Soviet’s communications infrastructure with a first strike, the Soviets developed a backup system that would give them the ability to call a second strike.

Although it has never been confirmed, it is widely believed that Russians have continued to employ the Dead Hand system after the collapse of the Soviet Union. Many believe that, due to their mysterious nature and the fact their physical locations have been moved, these three radio stations are part of the Dead Hand system.

If the signals stop, it could trigger the Russian nuclear arsenal.

Just to be on the safe side, let’s hope these three stations keep broadcasting their weird signals.