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

[Paul Nicholson <vlf0403@abelian.org>]

Some figures.

Average S/N: -60.7dB in 2.5kHz after sferic blanking;

Information bits: 427.5  (5.7 bits per character);
Code symbols: 3872;
Overall code rate: 1/9.057;
Total duration: 189728 seconds;

Info bit rate: 8.11 bits per hour (76% of channel capacity);

With such long messages, it isn't necessary to use a CRC.
The redundant 0.3 bits per character add up to 22.5 bits which
is plenty enough for the outer error detection layer to use.

With 22.5 plus the default 16 bit CRC, the optimum list length
for the outer layer is impractical and we don't get the full
coding gain.

On the Linux version you can set CRC size to zero to turn it off,
I'm not sure the Windows version will accept zero.

--
Paul Nicholson
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