Hi Paul,
Am 09.08.2017 15:39, schrieb Paul Nicholson:
I'm measuring about 0.016 fT daytime, 0.045 fT nighttime.
Daytime signal phase leads the night phase by about 67 degrees.
Combining and normalising day/night signals and excluding
the terminator periods gives
http://abelian.org/vlf/tmp/170809a.gif
Still not significant, only about 3.5 sigma, 10.9 dB S/N
in 1.13 uHz.
Thanks for that. I am happy with the result. It is not one of the main
bands anyway, just a short trip to 82 km :-)
So i will soon try some EbNaut with DL0AO.
The extra signal is raising the noise floor slightly
due to a tiny amount of distortion in the line driver and
isolating transformers.
Did you ever try optocouplers instead of isolation transformers? For
example an ADUM-4160 ? Could this be an alternative?
On the test bench the new rx does very
well: very low noise and low distortion. But with the full
signal from the antenna there is enough mixing to slightly raise
the noise floor. I just need that 0.1 dB and also to cure some
mechanical noises (microphonics) when the wind blows.
PS, the new rx also also covers 137 kHz!
The results on 137 kHz will be interesting. Will you publish the final
schematic when the system is completed?
73, Stefan
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