Hello Joe,
"... phase shifts in the fall were so close to 180 degrees... hope they come
back "
Annual repeatability of monthly-average daytime path delays (phase) is
surprisingly good, but a two-mode ray-hop approximation shows that a 1%
deviation on a given night from monthly-average nighttime D-layer height
could mean a 10 degree deviation in 8270 Hz diurnal phase change
Torbay-Todmorden, and given a dozen or so variables that often yield
night-to-night variations in D-layer height greater than 1%, and given
substantially larger seasonal variations, it could be quite a while before
the ionospheric diurnal XOR or T flip flop returns.
If your guard rail is workable, you would have enhanced opportunity for 180
degree diurnals, given higher radiation angle and broader/easier tunability
of frequency.
Hmmm... a broadly tunable guard-rail loop phase locked to a receiver would
seem to be the mythical longwave ionosonde (h', B); nice to have for ULF
experiments.
73,
Jim AA5BW
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of [email protected]
Sent: Friday, January 4, 2019 9:04 AM
To: [email protected]
Subject: Re: LF: VLF Carrier on 8270.01 Hz from a ground loop antenna - The
6th station on Paul's spectrogram
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 probablyB refer toB your carrier on 8270.0075 - yes I think you're
> right, there are littl
e Doppler wiggles, with higher frequency during the mornings thanB in the
evenings. This doe s make sense, consideringB day-night phase shifts
observedB inB theB long 13.3 hour FFT integration time.
>
> In Paul's 1.5 uHz spectrum coveringB 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 connectionB between your guard rails be approximately orientedB
towards us?
>
> 73, Markus
>
>
>
> -----UrsprC<ngliche 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
appearedB very strong on the NS-loop, which should have a null towards your
transmitter. The peak was - 120 dB on EW and V, andB -125 dB on NS, only 5
dB difference.
>>
>> I believe ourB N-S receive loop is seeing only theB skywave component.
Due to the angular orientation of yourB transmitB loop, the electric field
of the upward radiation will beB polarized in the NW-SE direction, with the
orthogonal magnetic fieldB pointing NE-SW. This polarization will be more or
less retained during the reflection (possiblyB rotated a bit by Faraday
effect). SoB the downgoing wave will also containB a magnetic field
componentB in the E-W direction, whichB is then picked up byB the NS-loop.
>>
>> So yes, earth loops are loops.
>>
>> Best 73,
>> Markus (DF6NM)
>>
>> -----UrsprC<ngliche 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-4-8270
>>> hz/
>>>
>>> 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 B B 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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