On 4/13/2012 6:04 PM, Scott Yost wrote:
> For the members who search this list looking for knowledge (but are hesitant
> to post),
> there are indeed several sites that provide audio clips of different RFI
> sources, to help you narrow down a search.
Yes, there are. One of the virtues of this list is that there are more
than a dozen true professionals working in the field of RFI, and they
step up when they feel someone is going down a blind trail Those experts
generally consider this sort of "noise signature" analysis as a means of
troubleshooting is misguided when the source is a switching power
supply, a computer clock, or other digital equipment.
Where noise signature recordings make sense is for noise sources that
are DIFFERENT -- electric fences, dog fences, and so on. Computer
clocks, chargers, and switching power supplies can be difficult to
recognize as noise without a spectrum display of some sort, because they
tend to be "bumps of noise" with an unstable carrier sort at the middle
of the bump, and the bumps repeat every so many kHz across the band and
slowly drift either in one direction as they warm up, and back and
forth. These noise sources raise the overall level on the band, but
they're hard to recognize without hearing the drifty carrier unless you
have that spectrum view. You don't need a full-bore expensive spectrum
analyzer to see this stuff -- it shows up quite nicely on a Panadapter.
There's a tutorial on RFI on my website, as well as a link to an
excellent piece written by a Belgian ham detailing some of his
noise-chasing exploits.
http://audiosystemsgroup.com/publish.htm
73, Jim K9YC
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