An interval signal is a characteristic sound or musical phrase used in international broadcasting and by some domestic broadcasters. It serves several purposes:

• It assists a listener to tune his or her radio to the correct frequency for the station.
• It informs other stations that the frequency is in use.
• It serves as a station identifier even if the language used in the subsequent broadcast is not one the listener understands.

The practice began in Europe in the 1920s and 1930s and was carried over into shortwave broadcasts. The use of interval signals has declined with the advent of digital tuning systems, but has not vanished.

Broadcasting services and interval signals

• BBC World Service in English: Bow Bells
• Radio Australia : Chorus of Waltzing Matilda on chimes
• Radio Canada International: First four notes of O Canada played on a piano
• Radio France Internationale : Electronic-disco, cumulating in the last 8 measures of the Marseillaise
• Radio Moscow (former service of the Soviet Union): Moscow Nights
• Voice of America: Yankee Doodle played by a brass band
• Voice of Russia: Chime version of chorus from Mussorgsky's Pictures at an Exhibition
• Radio Netherlands: Chime version of the Eighty Years' War song "Merck toch hoe sterck"
• Radio New Zealand International: the Bellbird, a distinctive sounding NZ bird species

External links

• Interval Signals Online
• Irkutsk DX Circle's Interval Signals Collection
• Nobuyuki Kawamura's Interval Signal Library
• TRS Consultants' Audio Bytes
• Uwe Volk's Sound Library (available both in English and in German)