Date: Mon, 24 Apr 2017 23:55:56 +0200 (CEST)
From: Jacek Lipkowski <sq5bpf@lipkowski.org>
To: rsgb_lf_group@blacksheep.org
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Subject: Re: LF: Re[2]: VLF: New carrier on 6470.005 Hz
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Too bad the explanation is so  simple, this nice fuel for wierd 
propagation theories :)

BTW in Poland we have 3kV DC for railways, so almost no harmonics.

VY 73

Jacek / SQ5BPF


On Mon, 24 Apr 2017, Markus Vester wrote:

> Date: Mon, 24 Apr 2017 16:40:19 -0400
> From: Markus Vester <markusvester@aol.com>
> Reply-To: rsgb_lf_group@blacksheep.org
> To: rsgb_lf_group@blacksheep.org
> Subject: Re: LF: Re[2]: VLF: New carrier on 6470.005 Hz
> 
> Hi Jacek,
> 
> in my case, the vast deficit on 6.47 kHz reception is clearly due to QRM
> from nearby railway lines. On
> http://df6nm.bplaced.net/VLF/screenshots/vlfwide_170422_1200.jpg , you can
> see two violet packs of unstable 33 Hz spaced lines, one around 3 kHz
> and the other above 6 kHz (note that they are stronger than they
> appear because the antenna ferquency response already rolls off below 8
> kHz). I am trying to mitigate the interference by tracking the carriers with
> SpecLab's automatic multinotch filter, but with limited success.
> 
> Looking at the excellent stability even at higher-frequencies, I'm pretty
> sure that SpecLab's 1pps processing is reasonably precise. In my narrowband
> instances, the noise blanker is preceeded by a 3.5 kHz wide Bessel bandpass
> with low ringing, covering both 6 and 8 kHz bands.
> 
> On one occasion, the DL0AO receiver in Amberg had produced a marginal 6.47
> kHz two-character EbNaut decode. But they are still using various improvised
> antennas until a proper VLF receive antenna will be ready.
> 
> I was actually hoping for better results because Stefan's good reception of
> my 6.47 kHz carrier proved that daytime propagation at our distance is
> stronger (in relation to ERP) and more stable than at 8.27 kHz.
> 
> Best 73,
> Markus (DF6NM)
> 
> 
> -----Ursprüngliche Mitteilung-----
> Von: Jacek Lipkowski <sq5bpf@lipkowski.org>
> An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
> Verschickt: Mo, 24. Apr 2017 17:10
> Betreff: Re: LF: Re[2]: VLF: New carrier on 6470.005 Hz
> 
> Paul receives anything (as usual). But the strange thing is that i can
> receive the 6470Hz signal with a mediocre setup (suboptimal antenna, qrm
> location in the center of Warsaw) at 900km, while Eddie (at 750km
> distance) and especially Markus (at 180km) can't receive.
> 
> The only other explanation (apart from lower qrm levels) might be the
> software used. I use Paul's vlfrx-tools, while Eddie and Markus use
> Spectrum Lab. The obvious differences are:
> 
> - gps timing (edge in speclab vs "stretched pulse" magic in
> vlfrx-tools). not sure what impact this may have
> 
> - noise blanker. most speclab setups use the noiseblanker on the whole
> spectrum (haven't seen your setup, but this is what most example
> configrations i've seen do), while the vlfrx-tools/ebnaut examples use the
> noiseblanker only on a 3kHz bandwidth segment centered around the rx
> frequency (this could be done with speclab easily too). also the speclab
> noiseblanker algorithm might be a bit different
> 
> Maybe try vlfrx-tools and see if there is any difference? And if so,
> tweak speclab to do the same (especially the filtering/noiseblanker
> should be simple)
> 
> VY 73
> 
> Jacek / SQ5BPF
> 
> 
> On Mon, 24 Apr 2017, DK7FC wrote:
> 
> > Date: Mon, 24 Apr 2017 15:18:45 +0200
> > From: DK7FC <selberdenken@posteo.de>
> > Reply-To: rsgb_lf_group@blacksheep.org
> > To: rsgb_lf_group@blacksheep.org
> > Subject: Re: LF: Re[2]: VLF: New carrier on 6470.005 Hz
> >
> > Hello Markus, Eddie, Paul,
> >
> > Thanks for the feedback, for trying and for the results.
> > Very strange. Paul has excellent results (as usual) but no decode for
> Eddie. On
> > 8270 Hz, the 'difference' is much less expressed. Does it have to do with
> local
> > QRM only? Maybe...
> > Maybe Alex has detected something.
> >
> > Pauls results are particularly interesting. 1+1 = 1 * 2 = 3 dB. Proves the
> theory
> > :-)
> >
> > The stacking would help to solve the problems it seems :-) A tool is
> needed...
> >
> > 73, Stefan
> >
> >
> >
> >
> > Am 23.04.2017 23:24, schrieb Markus Vester:
> > Hi Stefan,
> > I tried to receive your message on both days, and even added the two
> > recordings with equal weight, but unfortunately no decode. Guess I need a
> > railway strike :-(
> > Unfortunately no luck from DL0AO data either.
> >
> > Best 73,
> > Markus
> >
> >
> > -----Ursprüngliche Mitteilung-----
> > Von: DK7FC <selberdenken@posteo.de>
> > An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
> > Verschickt: So, 23. Apr 2017 0:42
> > Betreff: Re: LF: Re[2]: VLF: New carrier on 6470.005 Hz
> >
> > Hi VLF,
> >
> > another chance, the same msssage two hours earlier, improved timing
> towards
> > the east...
> >
> >
> > f = 6470.100000 Hz
> > Start time: 23.Apr.2017   05:00:00 UTC
> > Symbol period: 40 s
> > Characters: 2
> > CRC bits: 32
> > Coding 16K21A
> > Duration: 11h, 22m, 40s
> > Antenna current: 460 mA
> >
> >
> > 73, Stefan
> >
> >
> >
> 
>
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