30-01-2013, 02:18 PM
I remember an article many years ago (80s I think) from ETI magazine (whatever happened to that?) involving the design and use of a device called the Troglodyte. The unit was a two piece affair and was designed for mapping out cave structures underground. The caving team would have a transmitter unit housed in an ammo tin whilst the above ground team would map the underground teams location by the strength of the signals being transmitted. What struck me about the design was the frequency used, quoted as VLF bands, so I suspect that the ferret finder is working on those same frequencies. Interesting to note that the passage of time has shrunk the contents of an ammo tin down to a device small enough for a ferret to wear, a good example of progress.
