Re: VLF: Transatlantic success East to West

[Paul Nicholson <vlf0403@abelian.org>]

On 12/18/17 20:03, DK7FC wrote:
> Thanks Paul for the summary.
>
> Well, 8 days already and it gets worse. I think the phase changes are 
> not from my side, so it must be the path.
> I think i will give up now with this 3 character message. But even a 
> failed attempt gives us a set of data showing the difficulties and phase 
> variations.
> On the other side, a single character message is to short to let it be 
> as it is. So i'm trying a new message with just 2 characters before 
> going down to 5170 Hz.
> If possible, i daily feedback is apprechated.
>
> *f = 17470.1000 Hz
> Start time: 18.Dec.2017  21:30:00 UTC
> Symbol period: 45 s
> Characters: 2
> CRC bits: 14
> Coding 16K21A
> Duration: 09:12 [hh:mm]
> Antenna current: 1.2 A*
>
> 73, Stefan
Ok with that.  We're seeing several dB night to night change
in S/N and it doesn't follow the noise floor at Forest.

Relative RMS noise amplitudes in 1Hz band around the signal:

 10/11  Eb/N0 = -13.1 dB, noise = 2.12
 11/12  Eb/N0 =  -6.3 dB, noise = 5.49
 12/13  Eb/N0 =  -6.8 dB, noise = 3.60
 13/14  Eb/N0 = -19.6 dB, noise = 1.75 (stopped 03:40)
 14/15  Eb/N0 =  -6.0 dB, noise = 2.60
 15/16  Eb/N0 = -11.0 dB, noise = 2.54
 16/17  Eb/N0 = -14.6 dB, noise = 2.27
 17/18  Eb/N0 =  -9.9 dB, noise = 3.03 (stopped 04:19)

If anything, noisier nights are giving higher S/N.

Looking at NAA 24kHz, I see variations of the night phase
of up to 80 degrees.

It looks as if stacking repeated signals isn't going to
work so well at these high frequencies.  At least it
would need a dB or two devoting to a pilot carrier.

You'll just have to double your antenna current Stefan!

--
Paul Nicholson
--