"Problem" with the Rigol DS1052E. (SOLVED!) - Page 1
Forum section: electronics / general

author: Mint.
author_rank: Frequent Contributor
timestamp: February 01, 2012, 03:20:42 am
content: This is my first scope so I have no idea how scopes act and what they are supposed to be like. This topic is just an assumption that something is wrong.-This photo shows the waveform in 500ms. Now the thing here is that, the little dot of black in the waveform near the middle, I assume is how the waveform refreshes, just like in an analog scope with the cathode ray. Now the problem is that sometimes when I am working on waveforms 50ms+ (that is the point when you can spot the little dot of black) the dot starts at the middle of the scope, moves to the right and then we don't see it for a few seconds and then it pops up in the middle of the scope!Its just ridiculous I think personally, because you just lose half of the waveform, sure you can still see it, but how it acted at that exact moment in real time you cannot see.

author: ivan747
author_rank: Super Contributor
timestamp: February 01, 2012, 06:51:40 pm
content: I don't know much about scopes either, but, is the trigger holdoff function activated?

author: Mint.
author_rank: Frequent Contributor
timestamp: February 01, 2012, 07:33:53 pm
content: Nope it wasn't activated. Even when it is. The screen is black and then it triggers then suddenly half a waveform pops up on the right and then the right side is blank and the scope draws the waveform.

author: ivan747
author_rank: Super Contributor
timestamp: February 01, 2012, 11:22:42 pm
content: The problem looks like Dave's Lecroy problems. I have no idea what is causing it, sorry.

author: amspire
author_rank: Super Contributor
timestamp: February 02, 2012, 02:24:58 am
content: Quote from: Mint. on February 01, 2012, 03:20:42 amLet me guess, when you have the timebase set to 500ms/dev. the black dot takes 2.5 seconds to move from the center to the right, and then you have to wait another 2.5 seconds before it starts again?If so, the reason is that 500mS/div is 5 seconds for a full sweep. Since you have the trigger in the center of the screen, the scope will buffer 5 divisions of data points before it triggers. At the trigger point. it displays the first 5 divisions of information, and then you are seeing the real time writing of the following 5 divisions over the next 2.5 seconds.If that all fits, then you have nothing wrong. 5 seconds per sweep is just very slow. You can see it happening.Richard

author: ron
author_rank: Regular Contributor
timestamp: February 02, 2012, 03:47:57 am
content: ^ Exactly right. Screen shot shows 500mS/div. Nothing wrong with the scope.change thatto

author: Mint.
author_rank: Frequent Contributor
timestamp: February 04, 2012, 12:01:44 am
content: Quote from: amspire on February 02, 2012, 02:24:58 amI honestly don't understand many of the technical aspects of what you are talking about. Sorry about that. But I have uploaded a video just so you can see with more detailed if its alright or not.

author: amspire
author_rank: Super Contributor
timestamp: February 04, 2012, 12:38:48 am
content: Looks perfect to me.The blank part of the trace shows where the previous trace is being erased and the new trace is being written. If it didn't do that, how would you know what is the new data, and what is the old data? Since this is a repetative waveform, it just so happens that the old data and the new data are the same. It will probably make much more sense if you have the scope so it is not triggering off the waveform. You could switch both channels on, trigger off Ch1 (with no signal attached), and look at the waveform in Ch2. The waveform will now change position every new sweep, and it will be much easier to see what is happening.So why does the sweep start in the middle rather then the left? That is because you have the trigger point set to the middle. If you moved the trigger point to the far left, you would see the scope writing the new trace all the way from left to right.At the moment it sits there for 2.5 seconds buffering the data for the left half of the screen and then it triggers writing the new trace for the left half instantly, and then writing the right half in real time - thanks to the blanked section, you can see the writing as it happens.So it is all working absolutely perfectly.You just have to learn how it works - that is all. It is really important to understand that when you are viewing a trace that takes a whole 5 seconds to capture, the scope cannot do magic and somehow capture something that happens over 5 seconds in an instant. 500mS/div sampling rate does take a full 5 seconds to capture a trace, and that is so slow, you can see it capturing the waveform.Richard.

author: Mint.
author_rank: Frequent Contributor
timestamp: February 04, 2012, 03:06:45 am
content: Perfect! Thank you for your help everybody!