R: Re: LF: RE: RE: Almost touching the ground... | 12.47 Hz

["marcocadeddu@tin.it" <marcocadeddu@tin.it>]

Stefan,

I have already finished my words of wonder...

I'm sure you are looking for a suitable hammer to excite your ground-loop-rail-guard on frequencies below 1 Hz!
;-)))

Marco, IK1HSS

P.S. is it still the dreamer band?? Marcus you have to search for a new name! ;-)

----Messaggio originale----
Da: selberdenken@posteo.de
Data: 6-mar-2019 22.11
A: <rsgb_lf_group@blacksheep.org>
Ogg: Re: LF: RE: RE: Almost touching the ground... | 12.47 Hz





Hello Jim, Luis, Jim, 

thank you for the kind words. Well, yes, i would like to try 1 Hz and
less, and try to transfer a message below 1 Hz! But my soundcard cut's
off at 2 Hz, see attachment. Maybe this is due to the components on the
soundcard and can be extended downwards. But first i would try 2.97 Hz
or so. Currently i'm at 6.47 Hz but the E-field RX has a bad contact up
in the tree again. I need to find and solve that problem.

For the PA, doing 1 Hz or even 1 mHz is no Problem and i can hold the 5
kV rms at any frequency towards DC, including DC :-) If i can find the
time soon i will draw the schematic of the ELF PA and will show it here.

Currently i'm generating a spectrogram in SpecLab, running on a wav
file (mono, resampled to 240 S/s) that covers 8 days of the carrier
transmission on 12.47 Hz. It is set to 22 uHz FFT bin width and 3
hours/pixel scroll rate :-) Since SpecLab can do it in real-time only
it will take 8 days to complete the spectrogram, but never mind, we
have so much time, don't we?! I will show the result in a week then ;-)
But i already see that the trace is very strong, mch better than
expected and exactly on the frequency (as expected). Anyway it is good
to see that all this works so well in that frequency range. It looks
like a 10 km distance would be possible, if there would be a radio
amateur with the necessary equipment and motivation (both very hard to
find!).

On the tree i have some self-made QRM below 10 Hz. This comes from the
AM on the 5 V supply voltage. The culprit is the WLAN-stick and its
data packages, consuming a few 100 mA but only durng the times where
data is sent. It was filteres by a parallel C of 20 mF (low ESR) near
the E field amplifier and a series L of about 1 H. But there's still
that rest below 10 Hz. The E field amplifier uses a typical J310
circuit.
Now i have the idea to play with an LMP7721 Op AMP
instead, which should provide some rejection of the AC component of the
supply voltage. Will see if this works well on the tree, at least i
have a good signal to compare with. It would even allow to build in
some gain below 50 Hz, on the cost of a changing phase...

I wonder what distance could be made on the earth loop at ELF! I bet it
will work much better because i can keep the antenna current constant
down to DC and my PA already works below 10 Hz...

More soon.

73, Stefan


Am 06.03.2019 17:46, schrieb hvanesce@comcast.net:
> Stefan,
>
> Echoing Luis' comments this seems an inspiring journey into a wilderness
> area. If by ground you mean 0 dBHz, I will sincerely be on the edge of my
> chair waiting for your first spectral sub-surface (-0.1dBHz?) experiment.
>
> Fortunately the natural/cultural background has been characterized for your
> background-cancellation pleasure to -140 dBHz (see attached or page 4 of the
> link below), well below spectral ground.
>
> Natural/cultural background spectrum 45 dBHz to -140 dBHz: page 4 of:
> https://igpppublic.ucsd.edu/~cathy/Publications/Preprints/spectrum.pdf
>
> 73,
>
> Jim AA5BW
>
>
> -----Original Message-----
> From: owner-rsgb_lf_group@blacksheep.org
> [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of VIGILANT Luis
> Fernández
> Sent: Wednesday, March 6, 2019 3:19 AM
> To: rsgb_lf_group@blacksheep.org
> Subject: LF: RE: Almost touching the ground... | 12.47 Hz
>
> Hi ELF
>
> Absolutely outstanding achievement Stefan
>
> A different world and truly physics experiment. Then you will have to hear
> those blind minded regulators claiming to state rules at this frequencies.
> Always recurrent to contest, QSOs and bandplans ... LoL!!
> But that is all you can expect from the average HF byassed amateur-lawyers
> we already have at IARU
>
> This is like Antarctica. Mother nature and virgin territory for the real
> pyoneers who dare to explore it
>
> My pleasure and deepest recognition for your success :-)
>
> 73 de Luis
> EA5DOM
>
> -----Mensaje original-----
> De: owner-rsgb_lf_group@blacksheep.org
> [mailto:owner-rsgb_lf_group@blacksheep.org] En nombre de DK7FC Enviado el:
> martes, 05 de marzo de 2019 19:45
> Para: rsgb_lf_group@blacksheep.org
> Asunto: ELF: Almost touching the ground... | 12.47 Hz
>
> Hi ELF friends,
>
> During the last 2 weeks i've done another experiment on ELF, this time on
> 12.47 Hz, the 24 Mm band (wavelength 24057 km). Again i've crossed the local
> distance of 3.5 km. That's the lowest frequency i've ever been and it feels
> like i can see the ground already :-) The dimensions of everything down
> there are extreme. I've integrated 227 hours of a carrier transmission into
> one spectrum peak, it is shown in the attachment in 1.25 uHz. This carrier
> could have transferred an EbNaut message of nearly 100 characters.
>
> The ERP was 50 attowatt or -163 dBW and the antenna current was 170 uA only,
> despite about 5 kV antenna voltage.
>
> I'm now trying to put a step below 10 Hz but the RX antenna becomes less
> efficient with each Hz.
>
> 73, Stefan