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Date: Fri, 16 Mar 2018 14:35:20 +0100
From: DK7FC <selberdenken@posteo.de>
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In-Reply-To: <17dffb96-efc0-ce1b-700c-cd5d08cdf8e9@abelian.org>
Subject: Re: VLF: DK7FC > W1VD / K3SIW 8.27 kHz EbNaut - We don't give up!
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Paul,

AMAZING!
That was quickly! Many thanks.
I quickly run it through the file by W1VD, the 08.wav file. It improves 
the SNR from 4.67 dB to 7.57 dB, i.e. we gained 2.9 dB!
More later.

73, Stefan

Am 16.03.2018 14:21, schrieb Paul Nicholson:
>
> Here's an awk script to normalise the I/Q signal to the
> RMS amplitude.
>
> #!/usr/bin/awk -f
>
> BEGIN{
>    idx = 0;
>    sum_square = 0
> }
> {
>    stamp[idx] = $1
>    ival[idx] = $2
>    qval[idx] = $3
>
>    sum_square += $2*$2 + $3*$3
>    idx++
>
>    if( idx == 300)
>    {
>       rms = sqrt( sum_square/idx)
>
>       for( i = 0; i < idx; i++)
>          printf( "%s %.5e %.5e\n", stamp[i], ival[i]/rms, qval[i]/rms)
>       idx = 0;
>       sum_square = 0
>    }
> }
>
>
> Make sure the 'shebang' line is the first line of the script.
>
> Save it in a file, say, iqnorm.
>
> Make the file executable with: chmod +x iqnorm
>
> Then pipe the raw ASCII signal through it, so that instead of
>
>  vtwavex 26.wav | vtraw -oa | ebnaut -dp16K21A ...
>
> you run
>
>  vtwavex 26.wav | vtraw -oa | ./iqnorm | ebnaut -dp16K21A ...
>
> I've run it on my recordings (sample rate 1Hz) of the 5char
> transmissions and every single one has improved Eb/N0.
>
> Not yet tried it on the W1VD, K3SIW files.
>
> The '300' means 300 samples, so that's 300 * 0.45723950 ~= 137 seconds
> for the W1VD files, or 231.5 seconds for K3SIW.
>
> -- 
> Paul Nicholson
> -- 
>