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VLF: EbNaut for QSOs, beaconing and grabbers (?)

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Subject: VLF: EbNaut for QSOs, beaconing and grabbers (?)
From: DK7FC <[email protected]>
Date: Fri, 29 Apr 2016 23:43:29 +0200
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Now, i'm not sure what the marority is thinking about VLF these days. Many OMs are in the background. I hope it is rather interesting then annoying, that VLF stuff :-)

When comparing EbNaut with other modes, we can see that it seems to be the most effective mode, at least on LF and VLF.
On the other hand, it is complex to handle, maybe to complex for some. FFT data must be exported by SpecLab, start times must be known exactly, as well as the frequency and 'even' the message length and the symbol length. The frequency stability must be extremely good.
But from a different point of view this makes the mode as flexible and effective as it can be. So it is no critisation at all, i just have ideas how to extend the usage so it becomes practicable for more stations, maybe also on LF/MF.

Now, for a comparison to other digital modes which allow to have a QSO (e.g. JT9) or running a beacon and a 'grabber' window (WSPR or OP32) there are pre-defined settings, like the start time (each even minute for WSPR) or the frequency range or the content.

What i would like to have (and maybe others too) is a special EbNaut+SpecLab+Script(s) system that runs periodically and writes and displayes the decode result in a txt file that can be displayed on a grabber site, just like the OPDS32.txt on my LF DX grabber.
That system should be easy to install for most of the operators here. It should run automatically in the background and should consume less then 20% CPU power during decoding. A decode time of 10 minutes is no problem when it runs in the background anyway.

We could discuss and define different modes for VLF:
One mode could be 'beacon'. Definition (for example): starting each hour on 1 or 2 channels (selectable, 1 or 2 or 1+2) (= defined frequency); 30s symbols (or 10s or 60s, selectable, must be stated on the grabber page); 6 characters (for a longer callsign like IZ7SLZ)
With such a pre-definition, there's no need for an announcement, which is the main difference between EbNaut and other modes. The result, which can be even checked for plausibility (filtering nonsense-callsigns) could be displayed like the OPDS32.txt results, showing date, time, message, SNR and further relevant data. A script (written by Markus) could automatically start the decoder, read the FFT data, search for results, display them in EBN.txt and delete the FFT data file then. The FFT input size could be limited to a small value so the decode time becomes short and the file size becomes small. With 30s and 6ch this takes 280 minutes, so a beacon transmitter station could run 5 hour sequences. It's then a bit like a grabber indicating the transmitting station which QRSS mode must be choosen.

Another one could be 'QSO', with 30 or 60s symbols and 15 characters, using a single channel, i.e. a discrete frequency. A bit like JT9 but with stricter limitations.

What do you think, Markus and Paul. Could it be helpful to rise the activity in EbNaut, maybe also on LF? Would someone of you provide the scripts or maybe a special decoder edition for that task?

73, Stefan
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