Mike (K8CN) commented and asked me some great questions offline and thought
I should make a comment to the group as I'm sure others have similar
questions or comments. The issue is in regards to bandwidth selected and
the actual sampling rates of the various components of the system I'm using
being a limiting factor.
I've not yet investigated the sampling rate limitations my system has and
its impact on the displayed oscilloscope pattern. I'm confident my
software based oscilloscope system that's running at the same time on my
laptop as my SDR receiver is not sampling rate limited as long as my
bandwidth is 22 KHz or less. I have a lot more to investigate/learn about
my system and its bandwidth limitations especially as it relates to the
observation of power line noise and other broadband noise but I wanted to
share my finding as soon as possible with the group about using a wider
bandwidth than normally considered (wider than most conventional receivers
provide) when looking at power line noise based on my experience and that's
why I shared my initial bandwidth data/plots.
As I learn more about how my component sampling rates impact my results I
will share that information with the group, and a big thanks to Mike (K8CN)
for asking the great technical questions.
Happy Thanksgiving to everyone.
Don (wd8dsb)
On Wed, Nov 26, 2025 at 3:41 PM Don Kirk <wd8dsb@gmail.com> wrote:
> As I mentioned in a recent post I have had much better success observing
> the AM audio spectrum for power line RFI and other broadband noise when
> using a bandwidth much wider than conventional receivers typically
> provide. I now use at least a bandwidth of 25 KHz, and prefer a bandwidth
> of 100 KHz whenever possible. I just created a simple website to show the
> impact of a 5, 10, 15, 20, 25, 50, and 100 KHz bandwidth for those
> interested, and here is a link to the website:
> https://sites.google.com/view/bwforpowerlinerfi/home
>
> Just FYI, and 73.
> Don (wd8dsb)
>
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