“Twenty-four hours a day, seven days a week, for the last three-and-a-half decades, it’s been broadcasting a dull, monotonous tone. Every few seconds it’s joined by a second sound, like some ghostly ship sounding its foghorn. Then the drone continues. Once or twice a week, a man or woman will read out some words in Russian, such as ‘dinghy’ or ‘farming specialist’. And that’s it. Anyone, anywhere in the world can listen in, simply by tuning a radio to the frequency 4625 kHz.” Zaria Gorvett susses out some possible purposes of this Russian station – purposes that have their roots in the Cold War.