SDS1104X-E Unexpected Behaviour

[BillyO]

I discovered a bug in the Siglent SDS1104X-E.  I actually discovered it a while ago (when I found the offset in AC coupling mode on all 4 channels) but it's now becoming a bit annoying.

Offset and position do exactly the same thing.  They shouldn't.  Position should set the base-line (it does), offset should adjust the offset from base-line.  It doesn't, it just changes the base-line just like the position control does.  I am not sure if this was introduced in the latest software/firmware as that's what I'm using and have never used anything else.

Is there an official way to log a bug report?

Edit: Video added.

https://youtu.be/UzVjM4AltRc

[Martin72]

Short video would be nice...

[pope]

Interesting. I'll check mine when I get a chance.

[BillyO]

Short video would be nice...

What video format and size does the site permit?

[2N3055]

I discovered a bug in the Siglent SDS1104X-E.  I actually discovered it a while ago (when I found the offset in AC coupling mode on all 4 channels) but it's now becoming a bit annoying.

Offset and position do exactly the same thing.  They shouldn't.  Position should set the base-line (it does), offset should adjust the offset from base-line.  It doesn't, it just changes the base-line just like the position control does.  I am not sure if this was introduced in the latest software/firmware as that's what I'm using and have never used anything else.

Is there an official way to log a bug report?

Can you, please, explain what baseline, offset and position mean to you?
How did you set Vertical reference settings in Utility menu? (manual pg 220.)

[Martin72]

Short video would be nice...

What video format and size does the site permit?

Don´t know, me I´ve just upload vids to youtube, then linked here.

[BillyO]

Baseline is where you put the trace with the vertical position control.  The vertical position is, well the vertical position.  Where you set the trace to be vertically on teh screen.  It is marked with a triangular flag on the left.  Offset is where the trace actually is.  If offset=0 then the trace will be at the set position.  If offset=10mV then the trace will be 10V above where the set position is.  If the offset=-20mV then the trace will be 20mV below the set position.

I will try the two options mentioned on page 220 right now and get back.  However, this does not sound like the problem unless their English is wanting.

Edit:  Changing from fixed position to fixed offset had no effect.

[bdunham7]

How are you setting the 'offset'? 

[tautech]

C'mon Billy, screenshots please !

A picture = 1000 words.

[BillyO]

How are you setting the 'offset'?

With the "Offset" control.  How would you set it?

[BillyO]

C'mon Billy, screenshots please !

A picture = 1000 words.

Link added to a video in first post

[tautech]

C'mon Billy, screenshots please !

A picture = 1000 words.

Link added to a video in first post

Settings change required:
This video is private

Edit
Visible now.

[bdunham7]

With the "Offset" control.  How would you set it?

There are some 'offset' settings for rmath functions (DC offset in integration for example) but I've never seen or used the offset setting in the channel menu until I turned mine on just now and looked.  Indeed, there it is, and it is obviously just a replication of the position knob.  Why that is there, I've no idea.  My SDS2354X+ appears not to have such a setting, or at least I couldn't find it right away.

There was an uncommon feature of certain CROs that would actually allow you to put a separate (from the position controls) DC bias on the inputs, often much more than the position controls could achieve.  None of that is really necessary with a typical DSO, the position knob effectively does both.

Edit:  for those that don't see it right away, it is on page 2 of the channel menu.

[2N3055]

This whole "BUG!!" is between chair and oscilloscope. Please repair this thread title. Please first try to learn basic fundamentals  and after real knowledge and experience start naming things as "bugs".

Here you can of course ask how to use oscilloscope. But please, before it, try to even read the user manual first, even though it's boring.

What an amazing A-#ole!  First, I don't think you have any idea what I'm talking about.  Next, unless you have something constructive to add .. STFU!

I have read the manual.  Have you?  As bdunham7 mentions, it's found in the 2nd page of the channel menu and it is not even mentioned in the manual.


The "bug" might simply be the fact that they have two controls that do the same thing but are labeled differently.  Or it's not meant to exist.  That's fine.  Fix the "bug" by calling them both "position" or both "offset" or just removing it.  However, not being a Finnish twat, where I come from the words "position" and "offset" mean different things, especially in context of each other.

The title stays the same.  Now, vittuun!

Well, frankly, you have colorful personality yourself...
So let us all calm down and let's figure this out..

Position and offset are actually interchangeable in this context for reasons to be discussed. And it is why I asked what do you mean by this two terms. And I didn't mean by it to be explained as to what is meaning of these two english words (know that, thank you anyways) but as to what meaning you ascribe to them in context of the scope...

I don't have SDS1000X-E so I didn't know about this distinction. Touch screen scopes from them don't have it. And I agree with RF, it is not a bug. It might be confusing design choice or misnomer but not a bug.

What I presume it has it because offset/position in DC and AC mode will differ. Maybe they wanted to have separate control for the two.

Experiment: apply 25% duty cycle  0 to 1V squarewave to scope input.
Put it in DC mode. What you see?
Center it on the screen with vertical position knob (physical one on the channel).

Change channel to AC mode. What do you see?
Now try moving it up and down with vertical position knob (physical one on the channel).
Go out in DC mode? What you see?
Center it again.
Go back in AC mode.
Now try moving it up and down with offset function ( one in the menu ).
Go out in DC mode? What you see?

Do you see any difference in behaviour now?

Would you be so kind and try this? I am also curious what would the results be.

Best,

[bdunham7]

Do you see any difference in behaviour now?

I tried it and as I expected it made no difference.  In the AC-coupled mode, the baseline was displaced to -250mV as you'd expect, but the controls work the same way--if you select 'OFFSET' the multipurpose knob has the exact same effect as the position knob.  In the AC mode, the difference between the channel marker and the baseline of the waveform is always -250mV, in DC mode it always lines up.

The only thing different about the offset vs position is that if you push the multipurpose knob, you get the option of entering the value numerically, albeit painfully slowly with the turn/click method.

[BillyO]

Yes, I can be .. colorful .. especially when someone introduces themselves with a personal insult.
Enough of that for now.


I'll try what you suggest, but I think a key point is that there is no mention of this control in the manual.  Almost like it was there for beta test purposes but was not removed for the final product.

I'll report back on my findings.

Edit:  Findings below

25% duty square wave, DC, centered

AC, centered

AC, displaced down 1V using "Position" control

DC, displaced down 1V using "Position" control

AC, displaced down 1V using "Offset" control

DC, displaced down 1V using "Offset" control

[2N3055]

Yes, I can be .. colorful .. especially when someone introduces themselves with a personal insult.
Enough of that for now.


I'll try what you suggest, but I think a key point is that there is no mention of this control in the manual.  Almost like it was there for beta test purposes but was not removed for the final product.

I'll report back on my findings.

It probably was the opposite, added later to FW and not to manual...

[2N3055]

Do you see any difference in behaviour now?

I tried it and as I expected it made no difference.  In the AC-coupled mode, the baseline was displaced to -250mV as you'd expect, but the controls work the same way--if you select 'OFFSET' the multipurpose knob has the exact same effect as the position knob.  In the AC mode, the difference between the channel marker and the baseline of the waveform is always -250mV, in DC mode it always lines up.

The only thing different about the offset vs position is that if you push the multipurpose knob, you get the option of entering the value numerically, albeit painfully slowly with the turn/click method.

So it was not remembering different settings in AC and DC mode ..

Then it is really only an alias for vertical position button but to be accessed from menu.
I presume it is there because of remote control via HTTP interface...

[BillyO]

Then it is really only an alias for vertical position button but to be accessed from menu.
I presume it is there because of remote control via HTTP interface...

Yes, as I said in the beginning, it does the same thing but gives it a different name.

Makes no sense for the HTTP interface as it requires several more steps to access it.  The position control is easier to get to and easier to use, even through the webserver interface.

My previous post has been updated with the results of your suggestions.

So, my position on this is it is either a bug in the terms I previously described and should be corrected to provide a means to adjust offset of waveform from position, or it should just be removed.  It serves absolutely no purpose I can find as it stands.

[bdunham7]

So, my position on this is it is either a bug in the terms I previously described and should be corrected to provide a means to adjust offset of waveform from position, or it should just be removed.  It serves absolutely no purpose I can find as it stands.

Although you could provide a limited 'digital trim' as your offset, I don't think there's much utility in having some separate offset trim. It would be potentially confusing if you misunderstand it or forget that it is not set to zero.  As far as removing the menu item, that might break something as there may be some internal reason that it is there.  I would just chalk it up to a not-so-polished UI and ignore it. 

[BillyO]

I don't think there's much utility in having some separate offset trim.

There is actually.  I can think of 2 (maybe rare) use cases, but important if you need it.  Maybe Mr. loop, with all his superior knowledge of metrology, could expand on that?

I would just chalk it up to a not-so-polished UI and ignore it.

Probably the best way forward.

[Simon]

I got a siglent spectrum analyzer at work, not a fan of the interface on that, a working machine is one thing, communicating in another language (that of the user) is a different skill set.

[bdunham7]

There is actually.  I can think of 2 (maybe rare) use cases, but important if you need it.  Maybe Mr. loop, with all his superior knowledge of metrology, could expand on that?

On a CRO or other scope where the vertical position has to operate within reasonable limits, the addition of an adjustable DC bias on the input that allows you to offset the input by many divisions worth does have some uses, like looking at PSU ripple and more.  This was an uncommon feature on CROs.  But a DSO like the Siglent SDS1104X-E already has this feature built-in and incorporated into the vertical amplifier system.  Even if you did have some second offset system in the vertical amp, it would just add to or subtract from the first one.  The only other 'offset' I can think of that you could do is some sort of digital trim, but that would have to be pretty limited.  What use case do you have that isn't met by the system in the 1104X-E?

[BillyO]

What use case do you have that isn't met by the system in the 1104X-E?

Well, there is the case that kind of brought this back for me.  Looking at and making some measurements on a very low frequency not quite square wave signal.  Using AC coupling naturally distorted the waveform.  It would have been handy to use DC coupling and apply an offset to bring the signal back to where it should be.

The other use case is the problem I had before where there was a considerable offset in the vertical ranges below 10mV/div.

Yes, both are rare and both can be worked around, but an offset adjustment would make quick work of that.

[bdunham7]

Well, there is the case that kind of brought this back for me.  Looking at and making some measurements on a very low frequency not quite square wave signal.  Using AC coupling naturally distorted the waveform.  It would have been handy to use DC coupling and apply an offset to bring the signal back to where it should be.

Do you mean a signal with a large DC bias?  Or something else?

The other use case is the problem I had before where there was a considerable offset in the vertical ranges below 10mV/div.

This would be like trim or zeroing, I suppose it might come in handy on occasion.  But it wouldn't be stable.  I can't think of a single DSO that implements this directly.  You can do it with a MATH function, but that would be a lot of effort.