[RFI] 30m Interference
Paul Christensen
w9ac at arrl.net
Mon May 30 04:19:17 PDT 2011
Looking for clues concerning interference to the 30m band being caused by
what appears to be two digitally-modulated transmissions, one exactly at
9955 kHz and the other at 9965 kHz. The peak amplitude changes little with
changes in propagation, leading me to believe it is local, but I have
validated that the source is not in the immediate area of my QTH.
Looking at the print-screen, you will see the WWV carrier which does change
substantially in amplitude with varying QSB conditions. The amplitude of
the two interfering transmissions does slowly change over the long term.
For example, they are weak in the early morning, then rising during the
daylight hours. But again, they are not subject to QSB.
http://72.52.250.47/images/RF-Noise-053011-1.JPG
I would like feedback on the following. You may wish to reply directly to
me:
1) Can you see these transmissions at your QTH?
2) Any idea as to the type of modulation being used based on the spectra?
Many Tnx!
Paul, W9AC
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