A little bit of everything in this display except CB!
The slight slope of the floor is subtle impulse noise just waiting
to get loose.
The carrier looking stuff between 6MHz and 18MHz is shortwave.
Some CPD is trying to poke through the floor.
The narrow spikes centered at 21MHz are QPSK cable modem traffic -
probably me capturing this screen shot of my hub analyzer from my
back porch using a laptop.
(Courtesy - Poge Smit)
A couple of good displays of CPD with the one on the left being a classic
and the one on the right
being fairly deceptive due to the other various impairments. However,
CPD is the least of the
problems with these return paths as significant ingress exists in the
right display and major noise
underlies the peak hold CPD display on the left.
Neither display represents a usable return spectrum.
(Courtesy - Max Morales)
Impulse noise.
The left display is not uncommon and can be sporadic and difficult
to find.
The right display is real nasty and could probably be located by driving
around your plant with
an AM radio until all you hear is a horrible buzz! Though impulse was
described as the
culprit for the plot on the right, the junk also looks like a bad EOL
terminator and may very
well be a combination of both.
(Courtesy - Max Morales)
Pure amplifier and line extender noise.
(Courtesy - Max Morales)