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/sh/zu0k37z95ft1xfw/AAAgwsWDdfHVxTByuT8CyY_2a?dl=0 .
During the early morning yesterday (Mar 3), conditions into central Europe
seemed favourable. I downloaded several files and attempted to decode them.
Despite the fact that no carrier trace was visible in Domenico's 0.48 mHz
spectrogram https://www.dropbox.com/s/fsjkfuhggozzv5w/grabber.jpg?dl=0 , the
file centered on 1:40 UT produced a single good decode of VO1NA in South 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)
-----Ursprüngliche Mitteilung-----
Von: Markus Vester <[email protected]>
An: rsgb_lf_group <[email protected]>
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 until ~ 5
UT:
https://dl.dropboxusercontent.com/u/26404526/opds8.png
The FFT bandwidth had been halved to increase the aquisition time for your
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 individually tweak
the frequency offset in small steps, starting EbNaut several times 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 optimum total
message duration which is related to the inverse of the propagational Doppler
spread. If that is typically 10 or 20 mHz, only a couple of minutes 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)
-----Ursprüngliche Mitteilung-----
Von: jcraig <[email protected]>
An: rsgb_lf_group <[email protected]>
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
|
