Re: VLF: A message from W4DEX

[Paul Nicholson <vlf0403@abelian.org>]

> another big step since New Year 2015.

We can always count on Dex to try to push the limits out
further.

Last night the noise was low, so low that the best S/N
was bearing 290.  Dex on 284.6.  Usually the S/N
peaks up by aiming off at 310 to 330.

It was also the first time I used the new antenna
calibrations to mix the signal for a decode.

We used 8269 to avoid any overlap with VO1NA.

Given those conditions, we could have tried 42 chars,
16K25A CRC16 with 7 second symbols 23:00 to 08:05:04,
for Eb/N0 -0.15.

Correlations from on-line receivers (a loss of
perhaps 1 to 2dB due to vorbis encoding):

 Bielefeld 6918 km, Eb/N0 -12.3 dB;
 Cumiana   7173 km, Eb/N0 -10.0 dB;
 Warsaw    7681 km, Eb/N0 -19.7 dB;
 Forest VA  254 km, Eb/N0 -1.2 dB *Decoded* rank 0;
 Hawley TX 1816 km, Eb/N0 -7.7 dB;

The low Eb/N0 at Forest is surprising.  Something is wrong,
should be a huge signal. In 2015 Dex's EbNaut was even
visible on a spectrogram at Forest.

What do normal people do on Christmas day morning? I was
out at the H rx site with a spectrum analyser looking at
the amplitude of some MF signals (909kHz 5mV RMS on the
open circuit loop).

Meanwhile, I'm running low on celebratory cigars!

--
Paul Nicholson
--