Re: VLF: EbNaut transmissions on lower frequencies?, pre-tests: 6.47kHz / ULF coil

[DK7FC <selberdenken@posteo.de>]

Hi Paul,

Thanks for the most ineresting experiments, even if the result is 
negative sometimes.
Well it's not as easy as expected it seems. I did expect that the decode 
will be no problem with the added signals. Local experiments are not 
useful since my distance to the tree grabber is just 3.5 km. Anyway it 
is a real experiment with some path, so maybe i will do some QRP tests 
anyway.
Today the WX wasn't really good here and i've been motivated to continue 
to work on the large ULF coil. A very big step was done today, 
variometer is completed and i calculated that i need a 6th stack which 
must have 8 layers. Now 7 of them are completed! I will finish the 
winding today! That work took several month, 6 kg of cu wire is used, 
about 150€ just for the wire.
More later...

73, Stefan

Am 06.11.2016 21:50, schrieb Paul Nicholson:
> Stefan wrote:
>
> > f = 6470.00000 Hz
> > Start time: 03.11.2016   06:00:00 UTC
> > Symbol length: 30 s
> > Characters: 11
> > CRC 16
> > Coding 16K25A
>
> and
>
> > A second transmission is running now [5th Nov]
> > Same message, symbol length, phase orientation
> > and start time...
>
> No decode of either message.
>
> I added the two days coherently and that also failed to
> decode.  I tested the processing with simulated signals
> and that gave the expected 3dB gain.
>
> Looked at the cross correlation of the two days but can
> see nothing.  The simulated signals at about Eb/N0 0.0dB
> are visible on a cross correlation.
>
> This will only work if the received phase doesn't change
> much from one day to another.  We may need some luck, some
> stable weather and ionosphere.
>
> To keep the office warm, the computer is trying some
> range of phase shifts between the two days.
>
> --
> Paul Nicholson
> --