Hi Markus, Stefan, Group,
Putting some marks on the DL0AO spectrogram is very gratifying and an
indication that the RX setup is very good. I am trying to understand
what is being oberved and am happy to have your explainations.
The Doppler wiggles are associated with the motion of the ionosphere or
are they the result of phase changes from the change in path lenght
as the ionosphere (or virtual reflection point) moves up and down?
I went back through Pauls data to see if I could find other instances
where the central carrier vanished as it did this fall and found none,
not even during the spring equinox. It is as if the phase modulation
has been switched off.
Jim provided a diurnal phase ploy model output last fall. This must
change with the season. It seems remarkable that the phase shifts
in the fall were so close to 180 degrees. I hope they come back!
Thanks for the advice on the rail, Stefan. I'll test the continuity
if the wx improves. It is at a remote site and runs along the ocean in
your direction and is there to prevent cars from going over the 50m
cliff edge. Years ago, a chemistry professor told me he could hear BBC4
during the daytime when he brought his portble radio near the rail.
73 and HNY
Joe
On Sun, 30 Dec 2018, Markus Vester wrote:
Hi Joe,
you probably refer to your carrier on 8270.0075 - yes I think you're right,
there are littl
e Doppler wiggles, with higher frequency during the mornings than in the
evenings. This doe
s make sense, considering day-night phase shifts observed in the long 13.3
hour FFT integration time.
In Paul's 1.5 uHz spectrum covering one week, we now see a central peak on the
nominal frequency, assosiated by smaller AM and PM sidebands at 11.6 uHz
spacing.
Would the connection between your guard rails be approximately
oriented towards us?
73, Markus
-----Ursprüngliche Mitteilung-----
Von: jcraig <[email protected]>
An: rsgb_lf_group <[email protected]>
Verschickt: So, 30. Dez 2018 2:21
Betreff: Re: LF: VLF Carrier on 8270.01 Hz from a ground loop antenna - The 6th
station on Paul's spectrogram
Hi Markus, VLF,
Thanks for mentioning the 8270.0027 Hz traces at DL0AO. I've been watching
closely ever since. There appear to be dirunal frequency shifts on
this signal (or perhaps it is my imagination).
There are guard rails here that run in a straight line for about a km
that would make fine ground loops for VLF but getting across the pond
might be challenging.
73
Jor VO1NA
On Sat, 29 Dec 2018, Markus Vester wrote:
Hi Stefan,
a similar "miracle" occured at DL0AO: The trace from your ground loop
appeared very strong on the NS-loop, which should have a null towards your transmitter.
The peak was - 120 dB on EW and V, and -125 dB on NS, only 5 dB difference.
I believe our N-S receive loop is seeing only the skywave component. Due to
the angular orientation of your transmit loop, the electric field of the
upward radiation will be polarized in the NW-SE direction, with the orthogonal
magnetic field pointing NE-SW. This polarization will be more or less retained
during the reflection (possibly rotated a bit by Faraday effect). So the
downgoing wave will also contain a magnetic field component in the E-W
direction, which is then picked up by the NS-loop.
So yes, earth loops are loops.
Best 73,
Markus (DF6NM)
-----Ursprüngliche Mitteilung-----
Von: DK7FC <[email protected]>
An: rsgb_lf_group <[email protected]>
Verschickt: Sa, 29. Dez 2018 19:27
Betreff: Re: LF: VLF Carrier on 8270.01 Hz from a ground loop antenna - The 6th
station on Paul's spectrogram
Hello Jacek,
Oh, indeed, very clear! I did not expect this at all. The loop, if it
behaves as a loop at all (!), points towards Paul. It should have a null
into your direction. Our distance is 976 km !
http://k7fry.com/grid/?qth=KO02MD&from=JN39WI
Why do you see the signal at all? I'm puzzled but it feels good :-)
Tomorrow, maybe i'll do something on 2970.01 Hz!
73, Stefan
Am 29.12.2018 18:25, schrieb Jacek Lipkowski:
Good signal on my grabber:
https://klubnl.pl/wpr/en/index.php/klubnl-pl-grabbers/grabber-4-8270hz/
What is the antenna orientation?
jacek
On Sat, 29 Dec 2018, DK7FC wrote:
Date: Sat, 29 Dec 2018 13:43:14 +0100
From: DK7FC <[email protected]>
Reply-To: [email protected]
To: [email protected]
Subject: LF: VLF Carrier on 8270.01 Hz from a ground loop antenna -
The 6th
station on Paul's spectrogram
Hi VLF friends,
Since 11:35 UTC i'm running about 2.5 A antenna current into my 900m
long ground loop antenna. Frequency is 8270.01 Hz. The signal is very
strong on my own grabber in 57.6 km distance but also at DF6NM, DL0AO
and it looks like there is a peak now on Paul's spectrogram building
up slowly.
I intend to run the carrier for 2 hours or so, until the accu is
almost empty :-)
The H bridge PA voltage is 175 V and the power consumption is 450 W.
Today, the DC measuremant result is 66V for 1 A antenna current. It
is cold and wet!
More soon.
73 de DK7FC/P in JN39WI
PS: The QRN is exceptional low!!!!
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