Hello Jacek,
Yes i need/like to learn everything about this tool. You can publish it
on your website maybe, it could be too much OT here. But i'm starting
from 0.000 so i need some very basic stuff at the beginning. I like to
learn by myselfe in small steps, not directly looking for complete
scripts. I've ever been a lonely fighter, otherwise i wouldn't have done
any kite experiment!
I understand that the settings dependency is related to the QRN and QRM.
So you can do this only when the EbNaut message is already known, or you
need a plain carrier!?
But, can't you generate your own carrier by an internal signal generator
(even weighted, for a 3 axis system, i.e. a certain phase and amplitude
weighting for each channel, known from different messages in the past,
i.e. individual for each TX stn) to determine the optimum setting for
the individual transmission and its QRN/QRM situation? All this could be
put into a script, that calls the recording, adds the weighted test
signal, determines the optimum parameters and then applies them to
hopefully decode the EbNaut message?
I'm now struggling to decode my own message of the last 970 Hz
experiment, so i have a challenge! The spectrograms are already completed...
73, Stefan
Am 10.06.2017 23:15, schrieb Jacek Lipkowski:
Thanks for the transmission Stefan. although this is easy decode, it
can be used to optimise the receiver for longer messages.
I've tried to process this using different vtblank -a and -t
parameters, use ebnaut in signal analysis mode (knowing thr message in
already) and graph the resulting carried Eb/N0.
The pipeline is: vtread ... | vtfilter -h bp,f=6470.1,w=3000 | vtblank
-aXX -d 0 -tYY |vtmult -f 6470.1 | vtresample -r 240 | ebnaut -r240
-other parameters -d15 -f16 -M received_message. Only the -a and -t
parameters are changed. 14 -a values and 409 -t values were used (5726
calculations, about 1 day on 48 intel cpu cores).
The attached graph shows the carrier Eb/N0 for different parameters,
and can be used to optimise the receiving of longer messages. For this
transmission the sweet spot was -t 7500-8600 (for -a 1.7) and -t
8550-8750 (for -a 1.8), i'd use vtblank -a 1.7 -t 8050 -d0.
Beware that this is specific to qrm at this particular location, time
of day, thunderstorm activity etc. Beware2: this is for vlfrx-tools
0.7q (which is unpublished bu Paul, but downloadable by tweaking the
url, the official 0.7p works similar), vtblank from version 0.8
behaves differently (haven't checked why yet)
I can publish the scripts and the raw data in case anyone is interested.
VY 73
Jacek / SQ5BPF
On Mon, 5 Jun 2017, DK7FC wrote:
Date: Mon, 05 Jun 2017 14:41:28 +0200
From: DK7FC <[email protected]>
Reply-To: [email protected]
To: [email protected]
Subject: VLF: New EbNaut announcement...
Hi VLF,
For some local tests i like to transmit the 2 character message that
i already sent on 970 Hz 3 weeks ago. This time on 6470 Hz....
Such a short message with sch long symbols may be interesting for
newcomers or various tests by the established VLF receivers...
f = 6470.100000 Hz
Start time: 05.Jun.2017 13:00:00 UTC
Symbol period: 60 s
Characters: 2
CRC bits: 3
Coding 16K21A
Duration: 9h, 20min
Antenna current: ~ 460 mA
73, Stefan
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