Re: VLF: Back on 5.17 kHz / 58 km...

[Paul Nicholson <vlf0403@abelian.org>]

Stefan wrote:

> f = 5170.000000 Hz
> Start time: 04.Jan.2017   08:00:00 UTC
> Symbol length: 60 s
> Characters: 8
> CRC 16
> Coding 16K25A

> I will repeat the transmission starting [5th] 8 UTC...

Best decode with reference phase pattern: 30 30 0 0

Eb/N0 = +3.6 dB,   BER 35.0%, list rank 0.

S/N 20.24 dB in 11.8 uHz,  -63.0dB in 2.5kHz

The phase pattern is appropriate for an advance of the
signal phase during day relative to night.

Symbol error map (with 30 30 0 0 pattern):

 http://abelian.org/vlf/tmp/170106a.png

and with constant reference (0 0 0 0 pattern)

 http://abelian.org/vlf/tmp/170106b.png

Not much difference, 500/1408 symbol errors with constant
reference.  Down to 493/1408 with 30 30 0 0 pattern.

I haven't mentioned the message text because it's possible someone
else may be trying a decode.

> that  makes a fine record of 5.17 kHz successes
> between the two of you!

Indeed, 5170Hz seems to be quite a cooperative band to use.

--
Paul Nicholson
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