G4CNN wrote:
The signal was visible from about 22.00 last night (010205) until
06.00 this morning when it died out. I saw no clear "Dawn effect" on
the QRN in these images, but the QRN is low throughout, which might be
a result of using this resolution, or perhaps the different frequency.
That's interesting about the noise. I monitored VE1ZZ's frequency
(136.5) on Saturday night and also found no dawn effect on the
noise. I also wondered whether it was the frequency. Using Argo on
its full band (waterfall) mode, I monitored on Sunday night using a
500Hz filter from 137.2 to 137.7 (the DXers were affecting the plot
when I used SSB bandwidth) and there was a clear indication that
the noise was highest at the top of the band. This noise went down
at about 0626. (See attached JPG - highest frequency to the right).
This suggests that:
1) we are using the wrong frequency to listen to DX at night.
2) the noise is frequency selective. Perhaps it is linked to the
'Luxemburg effect' that we hear at the top end of the band late
evening. Does it effectively generate noise sidebands on the DCF39
signal? Or is there a strong wideband signal HF of the band,
3000km to the east?
More work is required on this one.
Mike, G3XDV (IO91VT)
http://www.lf.thersgb.net
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