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Date: Wed, 03 Jan 2018 13:02:47 +0100
From: DK7FC <selberdenken@posteo.de>
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In-Reply-To: <1e63b6ca-ae5c-176a-b9fa-1f035e5cc72e@abelian.org>
Subject: Re: VLF: Finally back on the 58 km band...
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Thanks Paul for the summary!

Well, you may have noticed that the tree has some problems. The WLAN 
link is not working correctly. In the Raspi (AP) log files i can see 
that it connects and disconnects each few seconds sometime. In the next 
moment it is stable for e few minutes... I spent a lot of time to 
exclude many possible reasons. It looks like there is a bad contact in 
the 2.4 GHz yagi outside the building. Last night i run a test with a 
local vorbis stream running over that AP when it was using a different 
antenna. The antenna was inside the building for that test. The stream 
is still running. It would not automatically try to reconnect, so there 
was not a single interruption since last night, which seems to confirm 
that the antenna is the problem.
Well, why do i tell that?
The antenna outside the building is just 1 m distant to the TX antenna. 
The antenna is floating. The shield of the coax cable of the antenna is 
coming inside the building, connecting to the WLAN stick, so it is the 
same ground as the Raspi2 (AP).
It looks like some RF current is coming inside the building that way and 
it looks like there is some coupling to the very low level of the E 
field feedback probe that is used for the phase correction in SL.
Last night there was no RF current since the antenna outside the 
building was not connected.
And now, there is a phase change of +15 deg on your side and and on 
Wolfs side !!!!!!!!!!!!!!!!!!!!!!!!!!!!
Not unlikely that this is caused by the changed configuration. 
Fortunately this is just a small phase change but it is not optimal!!!!!!!
So thanks for the feedback that shows this phase change!

73, Stefan

Am 03.01.2018 12:05, schrieb Paul Nicholson:
>
> Stefan wrote:
>
> > f = 5170.1000 Hz
> > Start time: 29.Dec.2017  15:00:00 UTC
> > Symbol period: 30 s
> > Characters: 12
> > CRC bits: 20
> > Coding 16K21A
> > Duration: 14:56 [hh:mm]
>
> Todmorden (881.2 km)
> --------------------
>
>  29/30 Eb/N0 +2.8 dB, S/N -26.2 dB/1Hz, phase 46.1 *Decoded*
>  30/31 Eb/N0 +4.1 dB, S/N -24.9 dB/1Hz, phase 44.2 *Decoded*
>  31/01 Eb/N0 +1.8 dB, S/N -27.1 dB/1Hz, phase 43.2 *Decoded*
>  01/02 Eb/N0 +1.5 dB, S/N -27.5 dB/1Hz, phase 57.6 *Decoded*
>  02/03 Eb/N0 -1.6 dB, S/N -30.6 dB/1Hz, phase 60.6;
>
> Bielefeld (303.8 km DL4YHF)
> ---------------------------
>
>  29/30 Eb/N0 +8.6 dB, S/N -20.4 dB/1Hz, phase -53.5 *Decoded*
>  30/31 Eb/N0 +8.3 dB, S/N -20.6 dB/1Hz, phase -52.1 *Decoded*
>  31/01 Eb/N0 +8.1 dB, S/N -20.8 dB/1Hz, phase -56.3 *Decoded*
>  01/02 Eb/N0 +8.4 dB, S/N -20.6 dB/1Hz, phase -47.9 *Decoded*
>  02/03 Eb/N0 +4.0 dB, S/N -24.9 dB/1Hz, phase -38.1 *Decoded*
>
> Warsaw (919.3 km SQ5BPF)
> ------------------------
>
>  29/30 Eb/N0  -5.4 dB, S/N -34.4 dB/1Hz, phase -20.3;
>  30/31 Eb/N0 -17.2 dB, S/N -46.2 dB/1Hz;
>  31/01 Eb/N0  -7.8 dB, S/N -36.8 dB/1Hz, phase -44.2;
>  01/02 Eb/N0  -6.1 dB, S/N -35.1 dB/1Hz, phase -36.1;
>  02/03 Eb/N0  -8.2 dB, S/N -37.1 dB/1Hz, phase   2.9;
>
>  Five stacked: Eb/N0 -2.1 dB
>
> Cumiana (504.6 km IK1QFK)
> -------------------------
>
>  29/30 Eb/N0 -5.4 dB, S/N -34.3 dB/1Hz, phase  176.7;
>  30/31 Eb/N0 -1.3 dB, S/N -30.3 dB/1Hz, phase -176.2;
>  31/01 Eb/N0 -4.9 dB, S/N -33.9 dB/1Hz, phase  177.4;
>  01/02 No data from rx site, ADSL fault;
>  02/03 No data from rx site, ADSL fault;
>
>  Three stacked: Eb/N0 1.1 dB *Decoded*
>
> -- 
> Paul Nicholson
> -- 
>