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

[Paul Nicholson <vlf0403@abelian.org>]

> Start time: 03.11.2016   06:00:00 UTC
> Symbol length: 30 s
> Characters: 11

No decode of this one.

> Time for a night-transmission test!

Let's try.

> Did you ever see a frequency offset or (relevant) time
> offset on my transmissions.

Frequency ok, carrier and successful decodes showed no
phase shift over long periods.  Signal too weak to check
for short period phase changes.

I haven't looked to bit clock offsets, I assume with these
long symbols that it won't be a problem.

> There are short periods in which the error density is
> very high,

Eg 13:30 to 14:30 but the noise was low.  And there are
short periods when it is completely red.  Even random
noise would only give half red.  Probably just statistics.

> It's a bit a pity that the phase varies so much between
> day and night.

No so much, 60 degrees, and I can compensate for that before
the decoder.   Day/night phase change should be less of a
problem as we go to lower frequencies.  LWPC is not much
help without a better ionosphere model than its basic
LWPM model.

--
Paul Nicholson
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