LF: Re: QRN

["Alan Melia" <alan.melia@btinternet.com>]

Hi Stefan, be very careful about your belief that the noise is lower in the
morning !! This may not be the case. It may be quieter but..........There
are two components of noise local and distant It could be that the distant
noise is not propagaing as well at dawn!! This is what happens on 136kHz. It
was thought for a long time that this was the best time for QSOs.......but
in practice it was found not to be so. The best time was usually a few hours
earlier. Just pre-dawn at mid-path. The noise was higher but the wanted
signal was also a lot stronger.

I am cautious about extrapolating 136 to 9kHz  but at 20kHz the morning an
evening dips on the stations monitored by SID detectors are due to increased
aborption. On 136 the mornings are quiet on the west coasts of Europe the
sun has destroyed the skywave from eastern Europe. On the Easten Coast of
the US the quietest time is the evening when the shadow is just aproaching
and the noise sources to the west are still in daylight. I admit I dont know
how the VLF noise behaves. Though I suspect a lot of that is lighning
induced.

Alan G3NYK
----- Original Message ----- 
From: "Stefan Schäfer" <schaefer@iup.uni-heidelberg.de>
To: <rsgb_lf_group@blacksheep.org>
Sent: Wednesday, July 07, 2010 11:09 PM
Subject: VLF: QRN


> Dear group,
>
> Today the average VLF QRN level was pretty low! Also the minimum QRN gap
> in the morning becomes braoder again. Maybe the most awaited DX period
> starts slowly?
>
> Best wishes, Stefan/DK7FC
>