Yes I have never seen anything quite like that. I have seen what might be
"gravity waves" in the inonosphere induced by the shock of a CME arrival.
They usually look more like halfwave recified sinewaves on a log amplitude
plot..........yes I made the beat 19.2 seconds.
Strange.
Alan G3NYK
----- Original Message -----
From: "Markus Vester" <[email protected]>
To: <[email protected]>
Sent: Friday, February 18, 2011 1:28 PM
Subject: Re: LF: HGA22 plot
Thanks Dex for sharing this extremely interesting observation. My first
thought was that the ripple might have been a beat pattern caused by an
interfering carrier at 1/20 Hz offset. But this explanation doesn't hold,
because the periodicity would have been broken up by HGA carrier spreading
due to the FSK telegrams. So it has to be some propagational effect.
On SXV, on rare occasions I had observed a slant color ripple pattern, i e
periodic variation in the apparent direction of arrival:
http://df6nm.bplaced.net/LF/sxv_ripples/sxv_ripples.htm
I had attributed this to an unusually late and Doppler shifted ionospheric
component. There may possibly a connection to aurora, and perhaps the recent
period of solar activity. However nothing unusual was seen here on LF last
night.
Best 73,
Markus (DF6NM)
From: Dexter McIntyre W4DEX
Sent: Friday, February 18, 2011 3:45 AM
To: [email protected]
Subject: LF: HGA22 plot
This evening I was watching HGA22 with SpecLab plotter. When I first
started the plot I noticed the signal looked as expected but when I
increased the speed I saw a sine wave shape on the plot. After watching
it for a while the sine wave pattern changed to a normal pattern. I
wish I had made more captures of the signal but I only made one which
shows the change.
http://www.w4dex.com/lf/HGA22_plot_18feb11.jpg
FWIW if anything,
Dex
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