----- Original Message -----
Sent: Sunday, April 07, 2013 10:18
PM
Subject: Re: VLF: Sunday morning test
8270.020 Hz
Peter,
LF,
daytime VLF propagation normally
depends on distance, solar elevation at midpath, and frequency. I
noticed that Uwe and Henny are both around 180 km from you. This
happens to be roughly the same distance as between Stefan and
myself, where we used to find a pronounced midday
minimum on 8.97 kHz. Ossi (200 km southeast) and I had the same
effect. On the other hand, the ~ 400 km path to OE3GHB and OK2BVG
was usually stronger during the day.
The distance between Appingedam and Nuernberg
is 525 km, and I'm really not sure if
there would be margin for a significant nighttime
enhancement between us. Keep in mind that Uwe is not only much
closer to you, but his ERP is probably an order of
magnitude larger than mine.
I have uploaded some screenshots from today to
http://df6nm.bplaced.net/VLF/8k27
. Paul's spectrogram clearly shows that my
frequency was below nominal between 10 and 11 UT. This is
corroberated by the Loran moire pattern, and also by a trace which
happened to be created by harmonic mixing in the high resolution
Opera-deep-search spectrogram. To trace down the problem I plotted the
samplerate deviation history from the VLF transmit samplerate detector. It
was tracking DHO 23.4 kHz with SpecLab's default settings (10 s update cycle
which is actually 1 / 0.072 Hz, 1 ppm maximum deviation). The samplerate was
generally very close, but there appeared a number of discrete +-
0.76 ppm excursions, possibly due to discontinuities in the ADC data
stream. After 9:50 these spikes became much more frequent and
apparently pulled up the average samplerate measurement
result, producing a -0.3 mHz error in the transmit frequency.
Around 11 UT I noticed that something was wrong, and increased the
measurement interval setting to 20s (1 / 0.036 Hz), which smoothed the data
and apparently eliminated the spikes. I also reduced the confidence
interval to +-0.1 ppm. Thereafter, the rest of the transmission from 11 to
13:45 was flawless.
Best 73,
Markus (DF6NM in JN59NJ)
Sent: Sunday, April 07, 2013 8:19
PM
Subject: Re: VLF: Sunday morning
test 8270.020 Hz
Hi Markus,
Unfortunately you where
already QRT befor the propagation got better. You'r
right, perhaps propagation to your direction is differend in relation
between Uwe and my QTH.
If you take a look (in my grabber)
at DJ8WX his signal and you's, there is not much
difference.
Uwe is already running for such a long time,
he leaves a impressive trace, but between 8 and 13 is his signal also
weak at my QTH.
Perhaps it is possible for you to switch
on a few hour between sunset and sunrise !
Best 73's, Peter.
----- Original Message -----
Sent: Sunday, April 07, 2013
12:35 PM
Subject: Re: VLF: Sunday
morning test 8270.020 Hz
Peter,
yes I was also wondering
whether it was really me but now it's sure. I think I did have
some samplerate tracking issues around 11 UT, but it looks good again now.
Interestingly but perhaps unrelated, DHO went off air for a minute at
11:18.
In the past we have observed that the
diurnal propagatipon pattern depends on the phase between groundwave and
ionospheric components, and thus on the distance between TX and RX. So it
may well be different between you and Uwe, versus you and myself.
Unfortunately I won't be able to transmit contiuously throughout day and
night, and will have to go off air around 13
UT today.
Best 73, and thanks again,
Markus (DF6NM)
Sent: Sunday, April 07,
2013 2:13 PM
Subject: Re: VLF: Sunday
morning test 8270.020 Hz
Hello Markus,
VLF
At first I was quite sure, but later in the morning I started to doubt whether I did receive DF6NM.
Meanwhile, in the afternoon I really see the trail of DF6NM appear in the spectrogram.
As you can see in the
traces of DJ8WX (in my grabber) the propagation is not good during
daylight between us.
I hope you are able to
stay on air for a while.
73s
Peter
