|Subject:||Re: LF: MF: EbNaut|
|From:||Markus Vester <[email protected]>|
|Date:||Thu, 3 Mar 2016 07:10:46 -0500|
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last night propagation between us was unusally stable and very strong until ~ 5 UT:
The FFT bandwidth had been halved to increase the aquisition time for your longer transmissions.
VO1NA, 477700Hz, 4K19A, 10char, 752*2s
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 ;-)
Hi Markus and thank-you for your patience and coaching. I was only there
Von: jcraig <[email protected]>
An: rsgb_lf_group <[email protected]>
Verschickt: Mi, 2 Mrz 2016 11:43 pm
Betreff: Re: LF: MF: EbNaut
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
On Wed, 2 Mar 2016, Markus Vester wrote:
> you've made it! Despite significant propagational spread, your message "G. MARCONI" was successfully decoded six times in Nuernberg.
> Wed. 2016-03-02
> start car. sym. offs.
> UT dB dB mHz
> 00:00 2.5 1.6 -3
> 00:30 2.2 0.8 0
> 01:00 2.1 0.8 -2
> 01:30 0.8 0.0 -1
> 02:00 nil 0
> 02:30 nil 0
> 03:00 3.3 2.5 -1
> 03:30 3.4 3.0 -1
> 04:00 nil +1
> 04:30 nil 0
> Thank you for your photons, and for your patience!
> All the best,
> Markus (DF6NM)
> -----Ursprüngliche Mitteilung-----
> Von: jcraig <[email protected]>
> An: rsgb_lf_group <[email protected]>
> Verschickt: Di, 1 Mrz 2016 8:45 pm
> Betreff: Re: LF: MF: EbNaut
> Well Done!
> The photon flux is on: 477.7 kHz, EbNaut parameters as before
> (10 chars 8K19A 752 1-second symbols starting on the half hours UT)
> Hope you have better luck if you want to try again, Markus.
> Joe VO1NA
> On Mon, 29 Feb 2016, Markus Vester wrote:
>> Congratulations to Paul and Domenico, this is a well deserved cup of tea!
>>> Maybe that is the farthest EbNaut on MF so far?
>> I think so. Actually the other day I had tried hard to decode VO1NA here, but never managed to pull enough of Joe's photons out of the noise.
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