If you have Real Player, go to: http://www.bbc.co.uk and click on the
link to Concrete Ears. It is fascinating.
Briefly this describes huge concrete acoustic dishes built in the
1920s, aimed at listening for enemy airplanes up to 25 miles away.
An artist is building new dishes for Folkestone (G) and Boulogne
(F). She claims that you will not only hear the sea but also be able to
talk to the person who is using the other dish 50km away. Hard to
believe that the QRM from the sea won't be a huge problem as this is
not even line of sight. As my wife's mother lives in Folkestone, I will
try it when it is built, and report back.
So, if you fancy breaking the 9kHz record without spending a penny
on electricty, simply build an acoustic dish!
Mike, G3XDV (IO91VT)
http://www.lf.thersgb.net
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