Re: LF: Earth modes and ebnaut?

[Roger Lapthorn <rogerlapthorn@gmail.com>]

Chris,

Some years ago (before my stroke!) I had correspondence with OFCOM about earth-mode (through the ground conduction) communication at VLF. Basically they did not want to know and were not at all bothered unless "undue interference" was caused to other users. As basically pen pushing bureaucrats they had no interest at all. To be honest, they found it too hard!  My distinct impression is go ahead and do not bother with licences! I have used earth-mode at up to about 18kHz, although I'd like to try higher frequencies at some point.

In my experience pure earth-mode works best with LOW conductivity between the electrodes, so the signal spreads.

Here, I am talking about conduction/induction communication. Stefan DK7FC used radiation I believe, using his earth-electrode "antenna" essentially as a loop radiator. This is my interpretation of how my earth-electrode "antenna" works at 136 and 472kHz.

Don't quote me - this is my interpretation of what OFCOM said. It is not a legal statement.

73s

Roger G3XBM

On 31 May 2016 at 15:34, Chris Wilson <chris@chriswilson.tv> wrote:

31 May 2016


Assuming it's legal to transmit VLF using earth modes, and this seems
an grey area, is anyone using Ebnaut for this communication method? if
I tried to master the complexities of it, not being very
mathematically astute, would anyone be likely to hear or look for a
signal? I am in north Shropshire, in open countryside, with plenty of
space for well separated earth rods, and the means to drive them very
deep into a soild of loam top, about a meter deep, then into what is
normally very wet sand as the water table here is high for most of the
year. Thanks



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Best regards,
 Chris  2E0ILY                           mailto:chris@chriswilson.tv