Message-ID: <593C6658.8090009@posteo.de>
Date: Sat, 10 Jun 2017 23:36:24 +0200
From: DK7FC <selberdenken@posteo.de>
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To: rsgb_lf_group@blacksheep.org
References: <592F348B.8060302@posteo.de> <593176F7.2050407@posteo.de> <59355178.2080007@posteo.de> <alpine.DEB.2.11.1706102254190.31885@mailn.lipkowski.org>
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Subject: Re: VLF: New EbNaut announcement...
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Status: RO

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 <selberdenken@posteo.de>
>> Reply-To: rsgb_lf_group@blacksheep.org
>> To: rsgb_lf_group@blacksheep.org
>> 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
>>
>>