Date: Tue, 7 Jun 2016 15:07:03 +0100
From: Chris Wilson <chris@chriswilson.tv>
Organization: Gatesgarth Developments
Message-ID: <844647135.20160607150703@chriswilson.tv>
To: Roger Lapthorn <rsgb_lf_group@blacksheep.org>
In-Reply-To: <CAHAQVWNRW8KmN01VfnPEFNHGSUyZgsqXqZT7d+2d=hMRm45TeA@mail.gmail.com>
References: <1685128417.20160531153441@chriswilson.tv> <CAHAQVWNRW8KmN01VfnPEFNHGSUyZgsqXqZT7d+2d=hMRm45TeA@mail.gmail.com>
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Subject: Re[2]: LF: Earth modes and ebnaut?
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Hello Roger and all the other VLF folk,

Thursday, June 2, 2016

 Sorry for the late reply, work has taken me away from play, but I
 want to thank you all for some very helpful replies. I am hoping
 later this month I can devote some time to building a good oscillator
 and doing some basic tests to see how stable i can get things. All
 this is a challenge to me, but getting going on LF was, and i got
 there in the end. Ebnaut is daunting to me still, as it seems very
 mathematically challenging, but hopefully if people have the patience
 to answer what will be some daft questions i hope to get there!

 As an aside I just bought one of those Red Pitaya boards and a friend
 has told me he thinks they are OK down at 136kHz and I will test it
 when it arrives. It should allow my TS-590 to be once again used for
 normal HF work, which I like for nattering.

 Again, thanks for all the insight!


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


> 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 knowand 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
> notbother 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
>  
>  
>  
>  --
>  
>  
>  Best regards,
>   Chris  2E0ILY                           mailto:chris@chriswilson.tv
>  
>  
>  
>