Message-ID: <4C358433.6090907@iup.uni-heidelberg.de>
Date: Thu, 08 Jul 2010 09:54:27 +0200
From: =?ISO-8859-15?Q?Stefan_Sch=E4fer?= <Stefan.Schaefer@iup.uni-heidelberg.de>
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Subject: Re: LF: Re: QRN
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Hello Alan,

Thanks for sharing your knowledge! Maybe i will have some questions to=20
you in some months when i want to come back to 137 with the 300m vertical.=
..

I am not an expert in interpreting the propagation on VLF, it is rather=20
a daily study of my grabber pictures and watching out for unnormalities=20
of the daily QRN changes. It has been shown that there is a sector=20
between about 7...10 UTC where the overall noise is at its minimum.=20
Within, and mostly only within that sector it is possible to get a reals=
=20
distance on VLF. During the summer that sector changed, in its deepness=20
and broadness. There is a second QRN dip in the evening that is not so=20
deep and that wasn't visible in some days of strong QRN levels. In the=20
last days i observed that the average QRN levels decreased. I will watch=
=20
out for any changes and try to interprete them ;-)

Maybe it would be good to have a long time carrier on the dreamers band=20
to observe the daily changes of the S/N so that we can confirm what you=20
said is valid for LF!? That could be a relatively poor ERP since one can=
=20
choose long integration times. That cannot be done with a kite antenna=20
so lets wait for some further well eqiupped TX stns there. They will=20
come! :-)

TNX es 73, Stefan/DK7FC


Am 08.07.2010 00:27, schrieb Alan Melia:
> 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..........Ther=
e
> are two components of noise local and distant It could be that the dista=
nt
> 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.......b=
ut
> 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 incre=
ased
> aborption. On 136 the mornings are quiet on the west coasts of Europe th=
e
> 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 aproachi=
ng
> 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 Sch=E4fer"<schaefer@iup.uni-heidelberg.de>
> To:<rsgb_lf_group@blacksheep.org>
> Sent: Wednesday, July 07, 2010 11:09 PM
> Subject: VLF: QRN
>
>
>   =20
>> Dear group,
>>
>> Today the average VLF QRN level was pretty low! Also the minimum QRN ga=
p
>> in the morning becomes braoder again. Maybe the most awaited DX period
>> starts slowly?
>>
>> Best wishes, Stefan/DK7FC
>>
>>     =20
>   =20