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Re: LF: EbNaut Autodecoder 137490 Hz

To: [email protected]
Subject: Re: LF: EbNaut Autodecoder 137490 Hz
From: Markus Vester <[email protected]>
Date: Mon, 15 Oct 2018 21:47:51 +0000 (UTC)
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Reply-to: [email protected]
Sender: [email protected]
Here are the Windows scripts which I am currently using for the EbNaut autodecoder. It is based on an already running opds-32 instance, providing a copy "fft.txt" of the current export file every 10 minutes. The "cleanup.bat" script, which is executed after each Opera correlation run, gets an extra line which creates a dummy file "do.txt" to invoke the Ebnaut decoder:


@echo DF6NM JN59nj  Opera-32 Deep Search  137.45 - 137.55 kHz  %date% %time:~0,5% >time.txt
@copy time.txt + headline.txt + detected.txt + detecold.txt opds32.txt >nul
@::copy c:\spectrum\data\*.txt c:\spectrum\data\saved\ 1>nul 2>nul
@del c:\spectrum\data\*.txt 1>nul 2>nul
@copy dirw.txt dirdone.txt >nul
@ftp -s:ftp_opds.txt >ftp_log.txt
@echo >do.txt

Here opds is running on my LF-grabber PC (called "SILVER") which is an old laptop under 32-bit Win-XP. The EbNaut decoder is on a different 64-bit machine, and it accesses the opds folder through Windows fileshares. Note that for some reason, the 32-bit Version of ebnaut-rx won't autostart using the -a option. This is the autodecoder script which becomes active after each half hour:


if exist \\SILVER\SharedDocs\Funk\Opera\opds\do.txt goto cont1
sleep 30
goto loop
del \\SILVER\SharedDocs\Funk\Opera\opds\do.txt
if %time:~3,1% EQU 0 goto cont2
if %time:~3,1% EQU 3 goto cont2
:: files should be ready within 5 minutes after half hour
goto loop
copy \\SILVER\SharedDocs\Funk\Opera\opds\fft.txt fft.txt /y
ebnaut_ifft3b fft.txt
del fft.dat
findoffset 0
set /p startoffset=<startoffset.txt
start /belownormal ebnaut-rx.exe -f fft.wav -N6 -p8K19A -k16 -L1000 -S3 -c2 -F-10 -T%startoffset% -a
sleep 2
start show_rawsyms3b.exe
sleep 38
taskkill /im ebnaut-rx.exe
taskkill /im show_rawsyms3b.exe
findstr "time found rank Eb/N0" fft-log.txt >>ebnautresults.txt
echo --------------------------------------- >>ebnautresults.txt
ftp -s:ftp_ebnaut.txt >ftp_ebnaut_log.txt
goto loop

As usual, you will need ebnaut_ifft3b.exe, ebnaut-rx.exe and the appropriate sr.txt in the decoder folder. Invoking show_rawsyms could just as well be omitted for unattended operation.

Taskkill is a workaround as neither ebnaut-rx nor showrawsyms will terminate itself. The decoder runtime has been limited to 40 seconds, which turned out to be long enough to run through all flat-phase decode attempts (on this machine).

The findoffset.exe utility is at
It calculates the startoffset to the next 10 minute boundary and writes it to startoffset.txt. To accomodate possible latencies (e.g. from a virtual audio cable), it can be called with an extra delay (in seconds).
For this to work, you should make sure that one export file starts before a half hour, and ends within a few minutes after the next half hour. For the usual 478 uHz 35-minute FFT , this can be achieved by starting the opds SpecLab instance in the second half of any 10-minute interval (e.g. between hh:55:00 and hh:59:50, but not between hh:49:50 and hh:55:00) 

The findstr command appends some selected lines from the log file to the end of ebnautresults.txt.

You will also need another copy of sleep.exe
and your own FTP control file which might look similar to this:


open *Server*
cd *Remote Folder*
put ebnautresults.txt

Hope this may be useful...

Best 73,
Markus (DF6NM)

Stefan wrote:

PS: I try to set up that auto-decoder as well. And maybe i'll be back on LF...

-----Ursprüngliche Mitteilung-----
Von: Markus Vester <[email protected]>
An: rsgb_lf_group <[email protected]>
Verschickt: Sa, 13. Okt 2018 13:32
Betreff: Re: LF: EbNaut Autodecoder 137490 Hz

Ric now running 30 characters 0.1 s symbols - Gotcha ;-)

73, Markus (DF6NM)

-----Ursprüngliche Mitteilung-----
Von: Domenico IZ7SLZ <[email protected]>
An: rsgb_lf_group <[email protected]>
Verschickt: So, 7. Okt 2018 12:17
Betreff: Re: LF: EbNaut Autodecoder 137490 Hz

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

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):

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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