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Date: Sat, 21 Mar 2015 12:49:40 +0100
From: wolf_dl4yhf <dl4yhf@freenet.de>
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Subject: Re: LF: eclipse observations on Twente WebSDR
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Thanks for the 'fullday' displeay Pieter-Tjerk - very impressive.

The frequency of that unstable QRM just below 500 kHz seems to depend on 
the sunlight intensity ... free-running solar cell inverter in the 
neighbourhood, or the AC mains voltage itself was affected ?
There were concerns by german electricity companies about how to keep 
the grid stable (when the sun re-appeared) but apparently nothing bad 
happened.

73,
   Wolf DL4YHF


p.s. no visible eclipse here, it was foggy until the afternoon and 
unusually cold.

Screenshot of VLF station fieldstrength (already posted in the yahoo group):

http://dl4yhf.darc.de/Eclipse_DL4YHF_2015_03_20.jpg


Am 20.03.2015 23:13, schrieb Pieter-Tjerk de Boer:
> During the eclipse (and in fact already a few days in advance), I've
> been logging signal strengths over the entire 0 to 29 MHz spectrum
> using my WebSDR system in Enschede, The Netherlands.
> As was to be expected, the eclipse's effect was very clear on medium
> wave broadcast signals, and also on longwave, with, as Roelof already
> pointed out, Iceland's broadcast coming in very strongly.
>
> Surprisingly, on one broadcast station I saw a dip in propagation rather
> than enhancement, namely the 216 kHz longwave transmitter in southern
> France. Could that be due to destructive interference between skywave
> and groundwave?
>
> Preliminary results, including a wideband waterfall display, are now on
> http://wwwhome.cs.utwente.nl/~ptdeboer/ham/eclipse2015/ ; but more
> analysis still needs to be done.
>
> Regards,
>    Pieter-Tjerk, PA3FWM
>
>
>