At 10:39 01/12/2006, Tom Althoff wrote:
Consistantly over the past 40 years I reaffirm on a daily basis
that, at least on 40M, as the sun lowers in the west I can hear
European stations about 45 minutes to an hour before they can hear me.
I have no explanation for it but suspect that the signal level is
the same on both ends but the background noise from the daylight
side masks the signal as it appears in Europe.
I think that Tom has made an important point here. Our ability to
copy is based on the signal to noise ratio. I think that the path
loss will be the same in both directions. However, if the
transmitting station uses more power or the receiving station has a
lower noise level, then the ability to copy will be markedly
different in each direction. Local band noise, QRN, QRM and so on can
make a big difference. Using a directional antenna for receive can
greatly improve S/N. One thing that I regularly notice as 20m starts
to close to North America from the UK is that while overall signal
strength can fade over half an hour by 2 or 3 S units, the band noise
also drops, so sometimes readability is hardly impaired. Eventually,
of course, the signal level drops to the point where S/N is degraded
and then you have to wrap the QSO up fairly quickly because it
disappear within fairly quickly after that.
Seasons greetings,
David, M0DHO.
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