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Re: LF: EbNaut Autodecoder 137490 Hz

To: [email protected]
Subject: Re: LF: EbNaut Autodecoder 137490 Hz
From: Domenico IZ7SLZ <[email protected]>
Date: Sun, 7 Oct 2018 12:15:03 +0200
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I ran an EbNaut beacon for almost 24h, since 10.00 UT of yesterday,  for testing the repaired Tx antenna and ground system.
I have monitored Both 'D' grabbers and they worked fine. I have obtained a lot of decodes. So very good job Markus with the integration of Window's programs SL and EbNaut-rx. I supposed you made some modifications at your previous EbNaut tools . Thanks for the new grabbers.

Tx setup here : SSB exciter frequency controlled by the old Jupiter GPS, 100 W PA, a small inv-L antenna (8 + 8 meters)  and linux program EbSynth by P.Nicholson. Time reference given by the same GPS using 'gdps' and 'chronyc' programs.

In the night i have also received, in the other 30-minutes time slot,  Ebnaut messages from Riccardo IW4DXW. Thanks Rick.

Luis wrote:
  Similar grabber for JT9 MF would be a great idea.

Yes. It is a good idea. So based on similar job already running (auto- wspr) , i have added such auto-decoder in my website:


It uses the same RX setup (RECEIVER JRC NRD-92M GPS referenced and miniwhip antenna) for recording the wspr band. Reception is very bad during the day but in nightime there is possibility to pick up signals from Central Europe.

So i invite the MF operators to test this grabber.

Thanks in advance.

73, Domenico IZ7SLZ






On Sat, 6 Oct 2018 at 12:13, VIGILANT Luis Fernández <[email protected]> wrote:
Hi EbNaut

Congratulations to both ! :-)

This will be a funny tool and a great help for newcomers to EbNaut, as Tx is the easy part of the game
Will be joining the "grabbepeater" as soon as I modify my D class PA for true 180º phase modulation

Similar grabber for JT9 MF would be a great idea. I can reach easily central EU in MF but can not receive
many of the stations. Last time I tried a CW activity night it was frustrating to receive in remote SDRs
central EU stations answering back and nothing here. Not just a matter of Rx noise. Many stations do
not have enought ERP to reach. So finally decided to use the SDR for QSO and it was fun

Yes, of course, this are not IARU blessed QSOs, but real FUN QSOs. And FUN is a must to increase
interest in this bands. We are in 21 century and ham radio also changed. We shouldn't be so square
minded to just think in therms of awards and standar QSOs. This is not HF. Same standards shouln't apply
Experimental bands are to experiment and try different aproaches with different rules. Not to run the same
old style HF QSOs, contests, awards and all that stuff

My two cents ! ;-)


73 de Luis
EA5DOM


De: [email protected] [[email protected]] en nombre de Markus Vester [[email protected]]
Enviado: sábado, 6 de octubre de 2018 9:17
Para: [email protected]
Asunto: Re: LF: EbNaut Autodecoder 137490 Hz

Last night, Domenico IZ7SLZ and myself had an unscheduled EbNaut two-way contact ;-) Well not quite a QSO, as we didn't exchange reports etc. I had sent a couple of 6-character messages into the blue before going to bed, and was pleasantly surprised this morning to find Dom's replies on all three automatic decoders.

Attached 477 uHz spectrogram from DL0AO shows both EbNaut signals, along with a few other WSPR and Opera transmissions, and 6.25 Hz spaced Loran lines from Slonim. Note that the receive level of nearby stations (DK1IS and DF6NM) is being reduced by SpecLab's frequency-selective limiter to avoid overloading and noiseblanker artifacts.

Thank you very much Dom! Now we're hoping for more and distant signals, like from Spain or U.S. ;-)

73, Markus (DF6NM)


-----Ursprüngliche Mitteilung-----
Von: Markus Vester <[email protected]>
An: rsgb_lf_group <[email protected]>
Verschickt: Mi, 3. Okt 2018 14:46
Betreff: LF: EbNaut Autodecoder 137490 Hz

After some playing around, we are running an experimental EbNaut autodecoder at DL0AO and DF6NM under Windows. Receive parameters are currently
 137490.000 Hz, 6 char, 3 s, 8K19A crc 16, start hh:00 and hh:30
and preliminary results can be found here (scroll to bottom):
DL0AO: https://vlf.u01.de/LF/LFgrabber/ebnautresults.txt
DF6NM: http://df6nm.darc.de/opds/ebnautresults.txt

This is nowhere near as perfect as Domenico's Linux solution, and our software contraption is nowhere near a stable state. Anyhow a few test transmissions with a couple of microwatts radiated power lead to useful decodes, and a trace also appeared in the opds spectrogram at DK7FC. It would be nice to find some more signals later...

Best 73,
Markus (DF6NM)

-----Ursprüngliche Mitteilung-----
Von: Domenico IZ7SLZ <[email protected]>
An: rsgb_lf_group <[email protected]>
Verschickt: Di, 2. Okt 2018 1:18
Betreff: Re: LF: 2200M EbNaut Beacon

LF EbNauters,

thanks to Markus and Stefan for the comments and to Rob for putting on air a very good signal.
I was also surprised to see the decode achieved by the auto-decoder without any time and frequency offset !
Propagation conditions are becoming better, but noise here is still high.
I tried a deep investigation: no further decode,  but with an offset of -0.0001 Hz and +0.005s (ooops !) i have improved the 2018-09-30_03:00 UT decode:

initial reference phase -62.3 amplitude 2.049e-01
phase   0    0    0    0    0
carrier phase: -6.9 deg
carrier Eb/N0: 0.5 dB
carrier Es/N0: -10.10 dB
carrier S/N: 19.87 dB in 672.0 uHz, -11.86 dB in 1Hz, -45.84 dB in 2.5kHz
elapsed 58
found rank 43 ber 3.4980e-01 Eb/N0 -0.6 M -7.389708042e+00 ph 0 0,0,0,0 [K3RWR_FM18QI_73]

Looking on the October 1st recordings, with these offsets,  i got another decode at 02:30 UT:

initial reference phase -6.6 amplitude 2.356e-01
phase   0    0    0    0    0
carrier phase: -1.2 deg
carrier Eb/N0: 0.4 dB
carrier Es/N0: -10.23 dB
carrier S/N: 19.74 dB in 672.0 uHz, -11.99 dB in 1Hz, -45.97 dB in 2.5kHz
elapsed 58
found rank 84 ber 3.6694e-01 Eb/N0 -1.7 M -7.504411221e+00 ph 0 0,0,0,0 [K3RWR_FM18QI_73]

QRB  is about 7600 km.

Working conditions here, (vintage 😀) as usual:
- miniwhip (a modified ex-Navtex antenna from Furuno ; see attachment)
- receiver JRC NRD-92M with external 10 MHz reference signal steered by  GPS
- a modest PC (Intel P4 CPU 3.50GHz x2) from scrap with Ubuntu 14.04LTS
- software vlfrx-tool from Paul Nicholson.

I have attached also the latest version of  the bash './autoebnaut' i.e. the list of the commands that recall vlfrx-tool programs to start the decoder each 30 minutes.
Other linux programs are running in background:
- vtcard and vttime to manage and calibrate the audio card
- vtwrite to store audio coming from receiver
- gpsd and chrony to manage the nmea and 1pps from neo8 gps (connected at serial COM1) and adjusting the PC clock.


73, Domenico IZ7SLZ


 
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