HFU HF Underground
Technical Topics => Propagation => Topic started by: Ray Lalleu on September 22, 2019, 2139 UTC
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Strange propagation tonight 22 Sep 2019
maybe from 19 UTC to 21 UTC (or later ?)
for SW signals (in 5 to 7 MHz at least)
varying from deep fades to huge booming signals.
( This topic will be moved to the propagation forum soon )
Nothing like that on 23 Sep. 2019
Time to move that to the proper forum.
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''Strange propagation tonight 22 Sep 2019
maybe from 19 UTC to 21 UTC (or later ?)
for SW signals (in 5 to 7 MHz at least)
varying from deep fades to huge booming signals.''
Ray, I did notice this too, but I wasn't paying particular attention
to the times when the SW signals were at their strongest.
(I was listening to free radio stations and some legal broadcasters on 6 Megs as well as 3.9 megs.)
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Welcome to the fall equinox, it's looking like a rough one. It's been acting up from UHF to the upper limits of HF here.
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foF2 has been bouncing around in the 5-7 MHz range, which can cause this effect. When it goes to just above the frequency you're listening to, the signal booms in (maximum signal strength is typically when the frequency of operation is just below the MUF). Then it drops a little, and the signal quickly fades away.
You can tell this is the case by examining the signal on a waterfall, and observing selective fading of the sidebands.
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You can tell this is the case by examining the signal on a waterfall, and observing selective fading of the sidebands.
That is an interesting visual effect. I enjoy the SDR waterfall as you can see many artifacts not otherwise noticed.
I was listening to 75m the other morning. Literally like a switch turned on and a half dozen stations around the east coast went from S3 to solid S9+ in less than a second.
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Yep.
Someone's playing with the big switch.
20m was dead when I tuned in a few hours ago and now there's plenty of sigs, same for 40m, dead flat, now packed. And for a brief interval the sigs jump up for a few seconds or milliseconds and back down to the bottom of the fft and histogram (what newbs call the waterfall).