73
Joe VO1NA

On Thu, 9 Nov 2017, Paul Nicholson wrote:

cat msg7 |
  ebnaut -et -N8 -k20 -p16K21A |
  sudo ebkey -S21 -m rp,gpio=23 -T '20171106 2200'

Decoded 'EINSTEIN' from the overnight 8th/9th transmission.

Eb/N0 = -0.5 dB, constant reference phase, BER 41.1 %

Symbol error map http://abelian.org/vlf/tmp/171109a.gif

 Night   Eb/N0    Phase   S/N
 6/7th  -20.0 dB          < -48 dB in 1Hz
 7/8th  -3.7 dB    97.6  -31.79 dB in 1Hz  (E+H)
 8/9th  -0.5 dB   128.8  -28.63 dB in 1Hz  (E+H)

 8/9th  -3.2 dB   131.1  H-field only
 8/9th  -2.3 dB   126.7  E-field only

Nothing at all from the 1st night and clearly something
broke during the 2nd night.

After a full phase search I got a slight improvement to -0.4 dB
with phase pattern -150,-150,180,180, which means the signal
phase is lagging a little (on average) after about 02:00.

This decode is about at the limit for the transmitter power and
message duration.  Looking at the error map, we might be able to
use a longer message but will probably only manage 9 chars max.

--
Paul Nicholson
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