Oscilloscope Zoom Out Quirk

[kcbrown]

...
I will say this: for single capture mode, it really should use all the available memory always.  This is because the history buys you nothing, since each time you press the "single" button it'll clear the history, so the scope may as well use all the memory for the one capture you're performing.  This is the one exception that Siglent should have made to the "what you see is all you get" behavior from the start.  Either that, or it should remember prior captures as long as the capture parameters (timebase, trigger settings, etc.) remain the same.

There is a common scenario where history mode makes perfect sense even in single mode.
And that is when you are experimenting, you tweak something in your DUT (analog or digital) and take single capture, tweak few minutes, capture that ... Now you have 20 captures over 2 hours. You go in history mode and overlay them, measure, decode. compare..
You can save them for documentation if you want then.

Except that on the Siglent, you can't do this.  I wish you could.

Whenever you hit the "single" button, it clears the history.

Did they change that behavior in the models above the 2000X+?  Because you certainly can't get multiple history entries via "single" on the 2000X+.

[2N3055]

...
I will say this: for single capture mode, it really should use all the available memory always.  This is because the history buys you nothing, since each time you press the "single" button it'll clear the history, so the scope may as well use all the memory for the one capture you're performing.  This is the one exception that Siglent should have made to the "what you see is all you get" behavior from the start.  Either that, or it should remember prior captures as long as the capture parameters (timebase, trigger settings, etc.) remain the same.

There is a common scenario where history mode makes perfect sense even in single mode.
And that is when you are experimenting, you tweak something in your DUT (analog or digital) and take single capture, tweak few minutes, capture that ... Now you have 20 captures over 2 hours. You go in history mode and overlay them, measure, decode. compare..
You can save them for documentation if you want then.

Except that on the Siglent, you can't do this.  I wish you could.

Whenever you hit the "single" button, it clears the history.

Did they change that behavior in the models above the 2000X+?  Because you certainly can't get multiple history entries via "single" on the 2000X+.

HUh.. let me check this..
No you're right, it does not...
I must have confused it with something that was discussed..
Sorry!

[Martin72]

Hmm....smells like a feature adding in future firmwares...

[2N3055]

Hmm....smells like a feature adding in future firmwares...

Not that I know of, really I remember a lengthy discussion about it and probably something left in my head...

[kcbrown]

OK, but you have to set the timebase to something.  How do you set it on your scope so as to get the maximum capture depth while also retaining the sample rate you want?

You are overthinking it. Zen master says: 'Try not to find problems that aren't there'.

Except I'm not overthinking it.  It's simply a question of how to get the capture characteristics to be what you want them to be.  Since there are situations in which you don't care about what the timebase setting is, it follows that you can then use the timebase to get the capture size you want in those situations.  Point being that those situations, which you explicitly called out, are precisely the ones where you have the fewest valid objections to Siglent's "what you see is all you get" approach.

Where the scope behavior you advocate for becomes truly useful is when you do care about the timebase setting and you want to use all of the available (or configured) memory for the capture.

All DSOs except for the ones from Lecroy and some older Siglent models, allow at least to force full memory.

You can force full memory in all of the Siglent scopes.  It's just a question of how to go about it.  For the "what you see is all you get" scopes, you force that via the appropriate timebase setting.

It's a tradeoff.  The downside of the "what you see is all you get" approach is that you don't get to use all of the configured memory while having a smaller timebase.  The upside of it is that (save for the maximum capture buffer size, which is separately configured) you fully control the entire capture configuration with a single setting (the timebase) and you always know exactly what you're going to get without having to reference anything other than the timebase settings.

Ideally, you want to be able to choose which approach to take.  Fortunately, Siglent has seen the light on that and now makes that possible.

One approach that no scope manufacturer I know of implements would be to allow the user to specify the maximum capture length as a multiple of the time represented by the screen as defined by the timebase setting  So, for instance, you might set it to 10x, and thus you'd always capture 10 times the amount of time shown on the screen.  Such an approach would retain the primary advantage of "what you see is all you get", namely that it would make it possible for you to always know exactly what you're going to get, and it would allow you to always zoom out by the configured amount.  The remaining memory (if available) would then be used to store prior captures in the way Siglent already does.

And several offer an automatic mode.

It's not clear to me what specific advantages that would have, most especially if the particulars of "automatic mode" are manufacturer-specific, as I'd expect them to be.

[Martin72]

The last scopes I got(private)/use(on work) having the auto mode as default setting.

[nctnico]

OK, but you have to set the timebase to something.  How do you set it on your scope so as to get the maximum capture depth while also retaining the sample rate you want?

You are overthinking it. Zen master says: 'Try not to find problems that aren't there'.

Except I'm not overthinking it.  It's simply a question of how to get the capture characteristics to be what you want them to be.  Since there are situations in which you don't care about what the timebase setting is, it follows that you can then use the timebase to get the capture size you want in those situations.  Point being that those situations, which you explicitly called out, are precisely the ones where you have the fewest valid objections to Siglent's "what you see is all you get" approach.

I suggest you re-read this thread. I have tried to explain how & why zooming out is convenient in great detail as good as I can in previous posts. If you think that these situations are the ones where there are the fewest objections to not having zoom out, then I'm afraid I can't explain it in a way you can fully understand it. Trying to explain again, would take this discussion in a circle. For me the advantages are crystal clear though and a scope which can not zoom out would seriously hamper my workflow efficiency.

[kcbrown]

I suggest you re-read this thread. I have tried to explain how & why zooming out is convenient in great detail as good as I can in previous posts.

I don't disagree that being able to zoom out is very convenient under some circumstances.  I wasn't disputing that.  I was responding specifically to the situations you called out in which you said you don't care what the timebase setting is.   Well, if you don't care what the timebase setting is, then what exactly is the advantage of being able to zoom out if you set the timebase to generate a maximum sized capture?  Or, alternatively, what's the disadvantage of not being able to zoom out under those circumstances?   You're probably twiddling the timebase knob either way in the event the timebase isn't something you care about, right?

If you think that these situations are the ones where there are the fewest objections to not having zoom out, then I'm afraid I can't explain it in a way you can fully understand it. Trying to explain again, would take this discussion in a circle. For me the advantages are crystal clear though and a scope which can not zoom out would seriously hamper my workflow efficiency.

Well, for any given situation, either you care about your timebase or you don't.  I presumed that those situations in which you don't care about your timebase are ones in which you could set the timebase arbitrarily, in which case you could just as easily set it to something that guarantees a maximum-depth capture.  If you want to be able to zoom out under those conditions, then you have to give up sample rate to do it.

So what exactly are you after under those conditions?

[Someone]

More choice is always good, but nctnico's unstated/shy/hidden refusal of zoom mode is around limitations of specific scopes (which are often not the scopes that this argument is "injected" into). It is valid for the very narrow case of those circumstances and specific scope, and the problem is it is presented as some generalisation or common issue completely out of context and unexplained.

Below is an attempt at a pictorial representation of some of the limitations/decisions/tradeoffs real people would consider.

If your scope only offers the first example of zoom (small view of trigger) it may well be impractical, or if zoom blocks some other function being used. But this is the sort of nuance that is never stated or avoided by nctnico, even when others are clearly saying and pointing to the second example (large view of trigger) at which point the argument that it is too hard to see becomes silly.

More choice, good.
Arguing people to un-mentioned corner cases to win internet argument, troll.

[electr_peter]

Data point on Micsig oscilloscopes. STO1104E allows to perform "zoom-out" if memory depth is set to manual mode (i.e. max 70M). In auto memory mode with most time bases there is no info beyond the data on screen. Memory size, sampling rate and time division settings are always shown on a screen and you can mentally calculate if the is data beyond the screen.

[Fungus]

Memory size, sampling rate and time division settings are always shown on a screen and you can mentally calculate if the is data beyond the screen.

Alternatively: Just look at the little indicator at the top... 

[electr_peter]

Good point, these icons represent memory situation clearly.

[teddychn]

Memory management and its options/guises are a recently added feature to SDS5000X in the FW version V0.9.7R2 before last.
It was developed in SDS2000X HD and SDS6000A.

aah interesting... so maybe it could be coming to any other remaining models featuring same / similar shared firmware platform? Or perhaps it requires a specific set of hardware common in those listed above? ^^

It would be an FPGA capture architecture thing I think, not the processor firmware as such.

That is correct.

I think Siglent can make it with tweaking the zoom mode. IMHO, just turn the upper-split screen into a time zone strip and that might do the trick. I guess it depends on Siglent's decision rather than architecture limitation.