Several privately-maintained sites, including those of G3YXM , ON7YD , GW4ALG , G3XDV and DK8KW cover all aspects of low frequency operation. The CSG site contains more wide-ranging information on cave surveying. Radio-location is an important aspect of cave surveying. David Gibson's radio-location page gives a bibliographic listing of papers on the subject by himself and others. Eventually he plans to place all these on-line.
Guidewire communication is a primary interest.
Graham Naylor is heavily involved in cave rescue communication in France and has carried out extensive work in the Berger. His Web site contains details of the original System Nicola and the Mark II system which is now being deployed by rescue teams throughout France. And in Belgium, Herman Jorens has been experimenting with a cave radio based on a design by John Hey. Details of his work with the Speleoclub Avalon can be found here . Magnetic Moments was a series of columns published in Speleonics , the newsletter of the NSS communications and electronics section.