UVB-76, also known as The Buzzer, is the nickname given by radio listeners to a shortwave radio station that broadcasts on the frequency 4625 kHz.[1] It broadcasts a short, monotonous About this sound buzz tone , repeating at a rate of approximately 25 tones per minute, for 24 hours per day.[1] On very rare occasions, the buzzer signal is interrupted and a voice transmission in Russian takes place.[2] It has been active since sometime in the late 1970s or early 1980s, when the first reports were made of a station on this frequency.[3] Its origins have been traced to Russia, and although several theories with varying degrees of plausibility exist, its actual purpose has never been officially confirmed and remains a source of speculation


A spectrum for UVB-76 showing the suppressed lower sideband.