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

[Paul Nicholson <vlf0403@abelian.org>]

On Oct 7th Stefan wrote:

> f = 6470.00000 Hz
> Start time: 07.10.2016   21:00:02 UTC
> Symbol length: 80 s
> Characters: 15
> CRC 16
> Coding 16K25A
> Duration: ?? Something arround 44 hours?
> Antenna current: 270 mA (ish)

Copied 'DK7FC JN49IK 73'

Eb/N0 = +1.1 dB   BER = 37.8%

Constant reference phase.

Error map http://abelian.org/vlf/tmp/161112a.gif

Using something that Markus suggested some time ago - to
normalise the symbol amplitudes by the average signal
amplitude.   I've tried this before on various tests but
never got an improvement, usually a small reduction of
decode performance.   But with this message straddling
day and night it obviously helps a lot.  I had to play
with a range of averaging periods and don't yet know
if I have the best one.

--
Paul Nicholson
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