Hi all,
I am a former lurker who just acquired my first oscilloscope. I've done a fair bit of reading and video tutorial watching, and I'm beginning to get comfortable with the scope, but I'm seeing something on mine that I haven't noticed in any videos I've watched, and I just wanted to ask about it. I hope this is not a ridiculous question to ask. I've done a lot of googling and been unable to find much relevant info, but maybe I just don't know the right term to search for.
Short version: On a lot of the square waves I look at, the edges (except the one I'm triggering on) flicker and jump left and right between two different positions.
So, I'm wondering if it's one or more of the below:
A) There is something don't understand about how to set up the trigger or other scope parameters to stabilize the waveform
B) The signals I'm probing just have some variance and the scope is accurately representing it, and I shouldn't sweat it
C) It's caused by some kind of external interference
D) There is a problem with my scope or probes
E) It's totally normal and I shouldn't worry about it
Here are some screenshots that show what I am talking about:
Here are some extra pieces of info:
Thank you!
I am a former lurker who just acquired my first oscilloscope. I've done a fair bit of reading and video tutorial watching, and I'm beginning to get comfortable with the scope, but I'm seeing something on mine that I haven't noticed in any videos I've watched, and I just wanted to ask about it. I hope this is not a ridiculous question to ask. I've done a lot of googling and been unable to find much relevant info, but maybe I just don't know the right term to search for.
Short version: On a lot of the square waves I look at, the edges (except the one I'm triggering on) flicker and jump left and right between two different positions.
So, I'm wondering if it's one or more of the below:
A) There is something don't understand about how to set up the trigger or other scope parameters to stabilize the waveform
B) The signals I'm probing just have some variance and the scope is accurately representing it, and I shouldn't sweat it
C) It's caused by some kind of external interference
D) There is a problem with my scope or probes
E) It's totally normal and I shouldn't worry about it
Here are some screenshots that show what I am talking about:
Here are some extra pieces of info:
- The scope is a Rigol DS1074Z.
- Signal sources have been various, but the two pictured here are from a pin connected to a two-line LCD display from an Arduino (yellow trace), and a 35 KHz square wave from a Jyetech FG085 signal generator I built from a kit. (http://www.jyetech.com/Products/085/e08503.php)
- I've tried a lot of the different triggering options and it doesn't seem to make a difference, but I have mostly been using edge triggering on rising edge in about the middle of the amplitude.
- I also tried fiddling with trigger holdoff, up to the waveform period length, and it didn't seem to affect it the left-right twitching.
- The probes I'm using came with the scope, and I have them set to 10x.
- With the signal generator, I tried connecting it different ways:
- I plugged it straight into a scope input with a BNC cable
- I plugged it into one side of an unterminated tee connector on an input (because I've seen people doing this online - I don't know why)
- I tried just hooking onto the signal generator output with the scope probe
- I've only seen this happening on square waves, not sine or other misc. waveforms I've looked at.
- It does not do it on the square wave that comes off the metal tab on the front of the scope.
- If I reduce the frequency from the function generator below 15 or 20 KHz, the effect seems to go away.
Thank you!