Message-ID: <000001c4f36a$3cd9b4c0$6507a8c0@Main>
From: "Alan Melia" <Alan.Melia@btinternet.com>
To: rsgb_lf_group@blacksheep.org
References: <8840D182F8BB7540B173D2B1FA0CA9AB034FEE8F@argos.clb.tcfr.thales>
Date: Wed, 5 Jan 2005 15:30:58 -0000
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Subject: LF: Re: RE: Re: RE: Re: DI2AG 440KHz...rapid fading
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Hi Jean-Louis, sometimes it does, but I think there are a lot of different
frequencies stimulated. I have had a few attempts to fourier analyse the
plots, but not with a great deal of enthusiasm yet. If I look at a lot of my
recordings there are obviously cases of beats between "waves" of different
periods. But theory.....well no not yet....I am an empiricist.....get the
measurements first and find a theory to fit later.

I think there are things called "gravity waves" talked about in the realms
of atmospheric and ionspheric physics (KN4LF's MF Propagation site has a
reference to them), but I have not yet found much else of interest
yet,except on I think it was the NOAA site, a program that prints out a
quasi 3d representation of an oscillating sphere. I can envisage a mechanism
that attenuates the high frequencies first but have not tried to work it
out. I think that ocean waves might be the nearest analogue. The problem is
that unlike water, the medium has a rapidly reducing density. Maybe there
are some keen mathematicians around who would care to play with the ideas.
Also the CME and solar wind is an "electro-magnetic" interaction. If it were
not for the earths field I think the solar ions would penertrate right down
into the atmosphere.
Like all things it is probably a lot more complex, but at least I have a
handle to enable me to talk about it and gather ideas.

Cheers de Alan G3NYK
alan.melia(at)btinternet.com

----- Original Message -----
From: <Jean-Louis.RAULT@fr.thalesgroup.com>
To: <rsgb_lf_group@blacksheep.org>
Sent: 05 January 2005 12:09
Subject: LF: RE: Re: RE: Re: DI2AG 440KHz...rapid fading


Hello Alan

Thanks for your interesting suggestion.

I'm wondering why the "oscillating mirror" frequency would decrease when
time passes.

The amplitude of a jelly portion wobble decreases when the losses dampen the
oscillations, but not the frequency which remains stable.

So I would expect some diminishing QSB amplitude on the DI2AG records, and
not QSB frequency decrease.

Please what is the underlying theory about this frequency vs time decrease ?

73

Jean-Louis F6AGR

> -----Message d'origine-----
> De : owner-rsgb_lf_group@blacksheep.org
> [mailto:owner-rsgb_lf_group@blacksheep.org]De la part de Alan Melia
> Envoyé : mardi 4 janvier 2005 18:17
> À : rsgb_lf_group@blacksheep.org
> Objet : LF: Re: RE: Re: DI2AG 440KHz...rapid fading
>
>
> Hi Jean-Louis, and Walter. I see a rapid almost cyclical
> fading on some
> 136kHz signals immediately after a geomagnetic storm (we have
> had several
> minor storms Kp=5 recently), the period usually lengthens on
> successive
> nights. I have suggested that this might be due to the plasma cloud
> "slapping" the ionosphere on one side and it then "ringing"
> like a wobbly
> jelly ( I must have eaten too much this Christmas !!) This
> would cause the
> "reflection" level to move up and down a few hundreds of
> metres maybe even a
> kilometre, which is quite sufficient to swing through a
> 180degree phase
> change. The movement required for a "null" at 440kHz is much
> less than at
> 136kHz. I would certainly be interested to see if the period
> of the fades
> increases over the course of the next few nights.
>
> Cheers de Alan G3NYK
> alan.melia(at)btinternet.com
>
> ----- Original Message -----
> From: <Jean-Louis.RAULT@fr.thalesgroup.com>
> To: <rsgb_lf_group@blacksheep.org>
> Sent: 04 January 2005 13:48
> Subject: LF: RE: Re: DI2AG 440KHz
>
>
> > Walter et al.
> >
> > I recorded your DI2AG sigs last night from 6 PM to 6 AM .
> > A quick exam on the 150 ARGO snapshots during my tea time early this
> morning  tend to show a deep  QSB (period around 1 minute).
> > Have you got other similar remarks ?
> >
> > 73
> >
> > Jean-Louis F6AGR
> > Loc. JN18DQ, near Paris
>
>
>