Sunday 23 February 2020

Finally, the winds subside.

After three weeks of winds that never really fell below 110km/h, some kind of quieter conditions have returned to North Wales.

Last night, the tower went back up, bringing several bands back into operation.

I ran WSPR at 1W, 7MHz, from my half sloper wire overnight.  Although not entirely surprising, it's always nice to plot WSPR spots and see how the advancing time of day affects the signals.

In this case, it's a plot of VK7JJ hearing my 1W, peaking at between ~08:00 and 08:30UT at the moment.  Contrary to what books will tell you, that the signal will increase during greyline (i.e. between sunset and the end of twilight), this result shows the signal becomes detectable by VK7JJ about two hours before sunset, peaks about an hour before sunset, and then vanishes about ten minutes after sunset.  At the moment, a month before the Vernal Equinox, the terminator is almost exactly opposite at my station.
VK7JJ hearing my 1W, 7MHz WSPR signal.
Situation as my signal becomes detectable at VK7JJ (ca. 2 hours before sunset there)
Situation as my signal peaks at VK7JJ (ca. 1 hour before sunset there)
Situation as my signal vanishes at VK7JJ, ca. ten minutes after sunset there.  Images: DXAtlas, with permission.

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