Date: Fri, 4 Mar 2016 21:12:25 -0330 (NST)
From: jcraig@mun.ca
To: rsgb_lf_group@blacksheep.org
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Subject: Re: LF: VO1NA - IZ7SLZ
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Hi Markus,

Thank-you yet again.  It's a amazing how this all works so well.
Of course, the it would have been impossible without some
very helpful advice!

73
Joe VO1NA

On Fri, 4 Mar 2016, Markus Vester wrote:

>
>
> During the last few nights, Domenico recorded spectrum data files around =
477.69 kHz and placed them in a public directory: https://www.dropbox.com/s=
h/zu0k37z95ft1xfw/AAAgwsWDdfHVxTByuT8CyY_2a?dl=3D0 .
>
>
> During the early morning yesterday (Mar 3), conditions into central Europ=
e seemed favourable. I downloaded several files and attempted to decode the=
m. Despite the fact that no carrier trace was visible in Domenico's 0.48 mH=
z spectrogram  https://www.dropbox.com/s/fsjkfuhggozzv5w/grabber.jpg?dl=3D0=
 , the file centered on 1:40 UT produced a single good decode of VO1NA in S=
outh Italy (see attached screenshots).
>
> So I happily pass the receive part of the MF EbNaut distance record on to=
 IZ7SLZ. Warm congratulations to Joe and Domenico!
>
>
> Best 73,
> Markus (DF6NM)
>
>
>
> -----Urspr=C3=BCngliche Mitteilung-----
> Von: Markus Vester <markusvester@aol.com>
> An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
> Verschickt: Do, 3 Mrz 2016 1:12 pm
> Betreff: Re: LF: MF: EbNaut
>
>
>
>
>
>
> Hi Joe,
>
>
> last night propagation between us was unusally stable and very strong unt=
il ~ 5 UT:
> https://dl.dropboxusercontent.com/u/26404526/opds8.png
> The FFT bandwidth had been halved to increase the aquisition time for you=
r longer transmissions.
>
>
> "G. MARCONI"
> VO1NA, 477700Hz, 4K19A, 10char, 752*2s
>
> Wed/Thu 2016-03-02/03
>
> start  car. sym. offs.
> UT    dB   dB   mHz
> 23:30 11.9  7.9   0
> 00:00 12.9  10.0 -1.5
> 00:30 16.1  13.6 -1.5
> 01:00 11.6  8.3  -1
> 01:30 16.9 14.2  -0.6
> 02:00 10.7  8.3  -0.6
> 02:30 17.9 14.4  -0.6
> 03:00 14.1 10.8  -0.6
> 03:30  5.7  4.4  -0.8
> 04:00  5.2  5.1  -0.8
> 04:30  3.6  4.0  -0.8
>
>
> Compared to yesterday, I think the much larger SNR is mostly due to more =
stable phase rather than longer symbols. I found that still had to individu=
ally tweak the frequency offset in small steps, starting EbNaut several tim=
es and watching the decode quality after the first linear-phase trials, as =
well as the dots in the rawsyms phase plot.
>
>
> Generally on MF shorter much shorter symbols may be preferable. I believe=
 that for such coherent and un-referenced signaling, there should be an opt=
imum total message duration which is related to the inverse of the propagat=
ional Doppler spread. If that is typically 10 or 20 mHz, only a couple of m=
inutes may be best.
>
>
> Hope that Domenico may have been able to break our distance record. Using=
 phonons instead of photons might be too much of a challenge though ;-)
>
>
> Best 73,
> Markus (DF6NM)
>
>
>
>
> -----Urspr=C3=BCngliche Mitteilung-----
> Von: jcraig <jcraig@mun.ca>
> An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
> Verschickt: Mi, 2 Mrz 2016 11:43 pm
> Betreff: Re: LF: MF: EbNaut
>
>
> Hi Markus and thank-you for your patience and coaching. I was only there
> to put your ideas into practice.
>
> I feel bad for making Paul's record so short lived, but very grateful for
> his software and guidance.
>
> Well lets go for 2 seoond symbols tonight and hope that enough phonons
> will reach Italy tonight.
>
> 73 and many thanks Markus and Paul
> Joe
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