Signal variations - Telecon

[George Fremin III]

I am watching the telecon from today and I have a few comments.

When I first got the grape Bill Engelke made a comment about the signal level changes in my graph as was blaming it on software.

What I see in my plots fits propagation and here is what I wrote him at the time:

I saw the mention of the low levels overnight for other stations out west here.  

The others in the video were west of me I think. 

I think what happens in the band goes long at night here until sunrise - so 10 mhz wwv gets weak here overnight.  And of course the dip in the daytime is the MUF going way high and the absorption going up between here and WWV during the day.

Looking at this VOACAP you can see the predicted signal levels match what you see in the captures.

And data for the MUF

And then I just saw the W0DAS part of the Telecon - and I see his has some variations as well - I do not know how far he is from the transmitters - but I have seen similar fading during the daytime on 40 meters on a 5 mile path to a station that I have line of site to.  The signal fades up and down.  Power / antenna is not changing.  I think the variations I see on that signal that is line of sight to me on 40 meters during the day is due to multipath.  I think some signal is coming direct and some is coming via the D layer during the day when MUFs are very high.  These two signals are adding and cancelling each other causing fading.  I would have never expected to see fading on this path - and indeed we did not really notice it when just chatting but putting on a carrier when I was trying to do some pattern testing on a new yagi it was very obvious.

Anyway - take my comments as just one take on that I think is going on with the signals. 

--

George

K5TR