Hi Domenico,
Thanks for the detailed report and the EbNaut decode over 1159 km. It
was still in daylight, so not bad for LF in mid June and a 376 second
long message...
Where does that -3.4 mHz offset come from?
Well, i realised that i don't even need to build the XOR gate circuit.
I simply used the PC that generates EbNaut for VLF, i.e. SpecLab, which
has a PPS+NMEA input. I choose a frequency of 12530 Hz. Then i built an
LF up-converter (in 2011) that has a LO of 125 kHz. So i come out on
137.53 kHz. That 125 kHz LO frequency (4 MHz xtal down-divided) is PLL
locked to the 10 kHz ref output of the old Jupiter GPS, which is
running here since 2010. The 10 kHz and the 125 kHz are also used on
the RX side. So i can generate stable signals on LF...
It seems it works :-)
73, Stefan
Am 19.06.2017 14:59, schrieb Domenico IZ7SLZ:
Hi Stefan, LF
as i suspected, i found my linux-pc storage hard disk full. A new 1 TB
HD is now in order.
So unfortunatly i can't give you an EbNaut report obtained using full
vlfrx-tools programs.
OPDS SL session has recordered a file witch covers your 16:30 EbNaut
transmission. I got a nice decode using almost the same offsets found
by Markus DF6NM.
I have tried to use also linux ebnaut, after converting the wave file
with following shell script:
------------------
#!/bin/bash
sox 06181637.wav -t dat -|
sed '/;/d' |
ebnaut -v -dp4K19A -F29.9966 -N10 -S1 -r111.11111 -c2 -L200000 -PS -v
-T724.5 # |tee dk7fc.txt
-------------------
But it gives, of course, almost the same results.
At the link http://qsl.net/i/iz7slz//DK7FC/
i have uploaded FFT raw and wave files, in case someone wants to try
the decoding.
So Stefan, congratulations for your first LF-Ebnaut transmission. Can
you tell us how did you generate the signal ?
There is a very easy and cheap method actually in use by Riccardo
IW4DXW and Tony IK1HGI for generating a coherent carrier for
EbNaut.Congrats to Riccardo for this nice idea.
They are using directly the timing pulse TP5 output of the neo-8 GPS .
In fact this timing port (TP5) can be reprogrammed up to 5 MHz.
The BPSK modulator consist of an XOR port in between the GPS TP5 output
and the PA driver. Cool !
73 Domenico, IZ7SLZ
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