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

[Paul Nicholson <vlf0403@abelian.org>]

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
--