Spectrogram of W4DEX at Forest, VA (range 254km) through
Mike Smith's receiver which is streamed over the Internet,
http://abelian.org/vlf/tmp/141201a.png
Appeared close to 8819.9 Hz then after the shutdown it came
back up near 8820.0 Hz.
The frequency was unstable, somewhere around 8819.9970 for a
while but it also spent some time near 8819.9985.
No chance of picking this up in Europe, although I did have
a look at a 30 minute slot which seemed reasonably steady.
But apart from this little problem with the frequency lock,
the signal looks pretty good.
Warren wrote:
> Can you point me to the coherent BPSK software?
I think so, Markus devised a way to send an encoded message
using Spectrum Lab. It is necessary to arrange something like a
DPDT relay to reverse the phase of the tx signal under control
of Spectrum Lab. The PC needs reasonably good clock discipline
(0.1 seconds or so) so that the bits are synchronous with UT
and the carrier has to be GPS or Rubidium locked, or maybe
from a very good OCXO.
I'll dig out the details in a follow-up.
--
Paul Nicholson
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