It is the 20th anniversary of the launch of Radiofax, the groundbreaking Short-Wave radio station.
Listen again to the first four test transmission broadcasts from the 1st to 4th of April (Easter weekend) 1988:
http://www.radiofax.org/audio_1988.html or Podcast feed http://www.radiofax.org/podcast_1988.xml
More about the station and its campaign to get a UK shortwave licence:
(info via Mike Barraclough, anoraksuk)