Measurement of reconstructed carrier from the 31.5 hour message,
In approximately 8 hour blocks (34.7uHz):
From To Signal S/N Phase Noise
16th 21:00 17th 05:00 0.077 fT 11.0 dB 112.7 0.022 fT
17th 05:00 17th 13:00 0.063 fT 17.4 dB 75.2 0.0085 fT
17th 13:00 17th 21:00 0.041 fT 9.2 dB 83.5 0.0143 fT
17th 21:00 18th 04:30 0.05 fT 3.8 dB 125.0 0.032 fT
Day/night phase shift up to 50 degrees which is about what was
expected, although this is a long average so it could be varying
more on shorter timescales to make the signal apparently weaker.
The 18th from 00:00 onwards was noisy.
Overall, would have needed to average about 14dB in this
bandwidth (34.7 uHz) to have a reasonable chance (~50%)
of decode.
Daytime is doing better than nighttime. In 17.36 uHz we have
17th 04:00 to 20:00 0.057 fT 18.2 dB
(eg 11 chars, 72 seconds, Eb/N0 = +0.23 dB)
Or, in 34.7 uHz
17th 05:00 to 13:00 0.063 fT 17.4 dB
(eg 9 chars, 40 seconds, Eb/N0 = +0.2 dB)
Conclusion is that it's not the phase that's blocking these
long messages, it's the poor nighttime S/N.
--
Paul Nicholson
--
|
