Hi,
Solid information and pictures have been difficult to obtain, but now it is coming out of the woodwork. With the introduction of Wilde Sau the proliferation of these systems and their use exploded:
http://www.gyges.dk/Wilde%20&%20Zahme%20Sau.htm
I have now added an additional page to the above:
http://www.gyges.dk/Leuchtfeuer.htm
please note embedded link to German documentation.
mfg
SES