[RFI] DSL RF pulsing centered at 20.5 MHz

Jay Bareman Radio_Q at mchsi.com
Thu Nov 24 13:06:04 EST 2005

I am hearing signals that are pulsing in nature with a rep rate of about 80
a minute, clearly not on a 1 second interval like a clock might be using.
There is no particular center frequency although it disrupts the entire 15
meter band. Watching the bandscope on my receiver shows the pulse in a
different part of the band every time it occurs which just confirms to me it
is a broad band signal, or a transient pulse.  It appears strongest at about
20.5 MHz and clearly with a vertical polarization.  The signals peak at
about S8 to S9 (with no preamps) on a force 12 vertical dipole mounted in my
attic and horizontal antenna's will greatly reduce the signal.


I started DF'ing the signal and wound up at a neighbors house about 6 houses
away, maybe 750 feet.  The signal is very strong at his telephone company
Network Interface Box where he has a white cable plugged into it that goes
into an air vent on the side of the house.  


I have not approached him yet but wanted to get some ideas from the group if
others have found anything like this.  We have SBC DSL lines in the area and
I suspect that is what he is using. 


I tried the SBC tech support on the internet and that led nowhere.


Ideas or experiences or suggestions.




Jim  K5QQ




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