A Russian Number Station which broadcasts a single buzzing, monotonous, note 25 times a minute every hour. One minute before the hour the tones changes to the manner it does in this clip. It's been broadcasting since about 1987 and has only been interrupted on a couple of occasions when it aired garbled, distorted, coded messages and then resumed broadcasting the buzz.
The picture is a satellite photo of its station.
(Any reference to dubstep in the comments section will be met with extreme disappointment)
