Hi Roger Peat or wet peat is quite acidic and so may be be quite a good
conductor. Of course in the absence of pipes the peat under the road surface
would be quite dry.....dont know about you but it has been very wet at times
today here !!
Alan
G3NYK
----- Original Message -----
From: "Roger Lapthorn" <[email protected]>
To: <[email protected]>; <[email protected]>
Sent: Sunday, July 17, 2011 2:43 PM
Subject: LF: Today's 8.7605kHz earth-mode tests (so far)
> An interesting discovery this morning. I've been trying long continuous
> carriers with short breaks for ID purposes.
>
> At my usual roadside test site (3.6km from TX) my signal was about 20dB
over
> noise with Spectran on 0.18Hz bandwidth. At a new test site (5.4km),
> believed to be well away from buried pipes, the signal was not visible at
> all with Spectran and the 80cm 30t loop. So, as an experiment I moved some
> 10-20m away from the road into a field which was bordered on one side by a
> fenland water irrigation channel. An earth-electrode pair was improvised
> with a baseline of 18m. One electrode (a large croc-clip) was dropped into
> the water and the other end (another large croc-clip) buried about 3cm
into
> the peat soil as far away as possible from the water channel.
>
> With Spectrum Lab I got good lock on GQD and my long test TX carrier on
> 8.7605kHz was clearly visible, but no trace at all was seen on Spectran
with
> 0.18Hz BW. SL was running with around 11mHz FFT bandwidth. To confirm it
was
> my signal, I got my wife back home to drop the carrier for 5 minutes. The
> attached screen-shot (LF reflector only) shows the carrier clearly visible
> before and after the 5 minute break. Note the 0.1Hz low frequency as the
> crystal oscillator had cooled and drifted when the carrier was turned back
> on.
>
> So, this is more evidence that the fenland water channels are involved in
my
> earth-mode propagation. Further tests are now needed to see if the signal
is
> detectable at even greater distances by using earth-electrode pairs with
one
> electrode in the fenland water channels. At the TX end the usual
> earth-electrode pair (one connector to the house water pipes and one an
> earth rod 20m away at the bottom of the garden) was used. The TX power is
> still just 5W from a TDA2003.
>
> The propagation is clearly conduction but this discovery opens up new
places
> to try to receive the signal. Results at around 1kHz and lower will be
> considerably better than at 8.76kHz.
>
> So much still to try and this is without radiating a signal!
>
> 73s
> Roger G3XBM
>
> --
> http://g3xbm-qrp.blogspot.com/
> http://www.g3xbm.co.uk
> http://www.youtube.com/user/g3xbm
> https://sites.google.com/site/sub9khz/
>
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