Swedish Rhapsody (numbers station)

Documents subsequently released from Polish intelligence revealed that the signal was produced by a music box manufactured by Reuge (pitched to sound like an ice cream truck) playing the song.

However, the last owners of the station, Foreign Intelligence Agency, claimed that the melody was Emilie Reisdorff's "Luxembourg Polka".

[1] Although the station was of unknown origin during the Cold War, declassified documents released by the Polish Government in 2014 revealed that the station was indeed operated by the government of the Polish People's Republic, and its secret police force, the Ministry of Public Security (Służba Bezpieczeństwa).

The Stasi "Sprach-Morse Generator" which provided the automated voice was of East German origin, and known to be used in similar coded broadcasts sent by the Main Directorate for Reconnaissance.

The documents further reveal that the station was broadcasting from at least the 1970s and transmitted on numerous shortwave frequencies, which were often changed depending on the time of the year.