Portland Bill F-Type Diaphone Foghorn (1993), one blast every 30 Seconds

Author this sound : The Association of Lighthouse Keepers provides a forum for everyone interested in lighthouses, lightships and aids to navigation from : Portland Bill Diaphone in 1993.

A fog signal for times of bad weather, the signal uses a four second blast every 30 seconds, with a range of 2 nautical miles. The Type F diaphone was decommissioned in 1996, but restored in 2003 for the benefit of visitors, where it is sounded every Sunday morning as an added attraction on the island but only used in foggy conditions if the lighthouse is out of operation [1]

Source
– Portland Bill from Trinity House
– Portland Bill Lighthouse from Wikipedia
– The forghorn : A celebration from BBC radio 4

Video
– Portland Lighthouse Diaphone Fog Horn (2006) par hellooldchap : « The old diaphone at Portland, Dorset, UK is sounded on Sundays between 1030 and 11, as long as the electric fog signal aint operating ! »
– and more on Youtube with tag « Portland foghorn »