This strange Russian radio signal has been transmitting beeps and buzzes since 1982. Nobody knows why

For the past 40 years, ever since the peak of the Cold War, a bizarre radio signal has confused scientists and radio operators worldwide. An old BBC article reported that the source of the signal is near St. Petersburg, Russia, and is believed to be the headquarters of a radio station called 'MDZhB'. Despite the station's continuous 24/7 broadcast of a monotonous tone on the frequency 4625 kHz, no one has ever claimed responsibility for it. Occasionally, a human voice interrupts the signal to read words like "dinghy" or "farming specialist," adding to the mystery, according to the BBC. Vice News further reported that some enthusiasts who explored the original location in Russia allegedly discovered a logbook documenting the messages transmitted by UVB-76. Also read | Russia tightens grip on grain exports as global wheat prices surge

A Cold War relic with modern mysteries

Initially, UVB-76 was believed to be part of the Soviet Union's vast communications network, and after the dissolution of the Soviet Union in 1991, the transmission continued to operate from Russian territory. The feed has gained numerous followers online, where users call it "the Buzzer". There are various theories around the radio transmission. The frequency is thought to belong to the Russian military, though they've never actually admitted this, said the BBC. Some believe UVB-76 is a number station used for sending coded messages to spies and operatives. The cryptic voice messages fit the pattern of traditional number stations, which have been used for decades by various countries for espionage purposes. Also read | German ex-soldier found guilty of spying for Russia Another theory suggests that UVB-76 might be related to ionospheric research, helping to study radio wave propagation through the Earth's atmosphere. This would explain the consistent signal and occasional variations. The Buzzer operates at a relatively low frequency known as shortwave, which allows it to travel great distances. In recent years, UVB-76 has undergone several changes that have reignited interest and speculation. In 2010, a significant spike in activity included more frequent voice messages, leading to renewed interest from amateur radio enthusiasts and conspiracy theorists alike, as per Popular Mechanics. Despite extensive monitoring and analysis by enthusiasts worldwide, the exact purpose of UVB-76 remains unconfirmed, perpetuating its status as one of the most compelling unsolved mysteries of the shortwave radio world.