I just got my pcsu1000 , regardeless of the input sensitivity selected i get a high frequency signal that seem to come from the usb.
I was using a long usb cable so i reverted to the short cable but the signal is still there.
In this picture , there is no probe connected so there should be no signal present.
Any clues on what is producing these signals ?
–> Please do not include big pictures on this forum, post only a link ! THX.
There is always about +/-1 pixel noise on normal screen. On big screen this is more visible.
You can use the averaging to reduce the noise.
Select Options -> Average.
Here example images with and without averaging:
^+1, that is normal for DSOs…
Here is a trace from my $3000 Lecroy WaveJet 322, with the same vertical and timebase settings–and the input grounded:
Analog 'scopes mask this through the inherent averaging of the analog signal chain…
Here’s another example: Tektronix - input grounded…
For a nice warm and fuzzy reference, here’s what it looks like on a 30+ year-old 275MHz HP 1726A:
