Have you ever seen one. http://googlesightseeing.com/2010/08/“the-buzzer”-speaks-voice-transmission-confirmed-at-uvb-76/ Now you have. It's an old article but could be of some interest.
They are definitely one of the most scary things. You could be listening to someone being given a assassination mission or codes to change the course of a missile.
Was actually checking up on them due to Ingress, a collection of them and their suspected or accurate origins.
