Re: LF: MF: EbNaut

[Markus Vester <markusvester@aol.com>]

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 <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

On Wed, 2 Mar 2016, Markus Vester wrote:

> Joe,
>
>
> 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 <jcraig@mun.ca>
> An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
> 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.
>
> 73
> 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.
>>