Oscilloscope Zoom Out Quirk

[nfmax]

One way is as good as the other, maybe, but DSOs are designed, primarily, around zooming in. Zooming out, you are going to find yourself going against the grain. Like a left-hand thread works just as well as a right-hand thread, but insisting on using left-hand thread screws everywhere may be a problem.

[BillB]

All true believers shall break their eggs at the convenient end.

[nctnico]

One way is as good as the other, maybe, but DSOs are designed, primarily, around zooming in.

Says who? Nobody provided any evidence that zooming out is not the way an oscilloscope works. The fact it (recording beyond the screen) is possible on many oscilloscopes suggests that those are actually designed to work this way. It seems Keysight even went through the trouble to make single acquisition mode different compared to normal acquisition mode to support zooming out after a capture by recording beyond the screen. No, the problem is definitely that some seem to be stuck in the idea that you should always zoom in and use exact settings. Even when making those settings and zoom window adds zero benefit to solving the problem at hand.

[Gandalf_Sr]

Click this link to have an unlimited supply of reading material on this subject...

[Martin72]

One way is as good as the other, maybe, but DSOs are designed, primarily, around zooming in.

Says who? Nobody provided any evidence that zooming out is not the way an oscilloscope works. The fact it (recording beyond the screen) is possible on many oscilloscopes suggests that those are actually designed to work this way. It seems Keysight event went through the trouble to make single acquisition mode different compared to normal acquisition mode to support zooming out after a capture by recording beyond the screen. No, the problem is definitely that some seem to be stuck in the idea that you should always zoom in and use exact settings. Even when making those settings and zoom window adds zero benefit to solving the problem at hand.

User tv84 nailed it in it´s last post here exactly, in my opinion.

[2N3055]

One way is as good as the other, maybe, but DSOs are designed, primarily, around zooming in.

Says who? Nobody provided any evidence that zooming out is not the way an oscilloscope works. The fact it (recording beyond the screen) is possible on many oscilloscopes suggests that those are actually designed to work this way. It seems Keysight event went through the trouble to make single acquisition mode different compared to normal acquisition mode to support zooming out after a capture by recording beyond the screen. No, the problem is definitely that some seem to be stuck in the idea that you should always zoom in and use exact settings. Even if making those settings and zoom window adds zero benefit to solving the problem at hand.

You are now inventing that Keysight memory management was made the way it is "for the purpose of enabling zoom out" while presented with plenty of evidence that it doesn't even work that way when used in a scenario as explicitly designed by you.

You are confusing (at this point obviously intentionally, not wanting to admit the truth) that fact that something exists, is not a proof of intention. That kind of memory setting is probably there because it was easier for manufacturers to implement memory management, or for support for digitizer mode when using scope as digitizer. Or whatever. Only instrument designers know.

And zooming in and out provides same benefit as it provides same data for analysis. That was also proven several times by different people.
Once you capture data, both methods have same data and same analysis capabilities. I said that at the begining, tv84 said it very nicely (and more concise than I'm capable off.)

But, at this point you are insulting those that prefer to use proven techniques and use exact settings as being backwards. 
They are stupid because they read manual. Nice.

Your only  reason to insist on you way is that you refuse to learn how to use zoom mode. You simply hate it, for some reason.
So you devised method that you like better, that works on some scopes, and don't on others.
And you like it, and you find it useful. Good for you. I'm happy for you. And you shared it with us. Thank you for that. That was nice of you. Unfortunately, I couldn't find no merritts in it for me, for what I do, and how I do stuff. But thanks anyway. It was a gesture that counts.

[Someone]

This is why Keysight are clever in how they do it. They know that in trigger/Auto continuous update mode you don't care about extra data outside the screen, you just want the fastest update rate possible. Only when the user specifically requests STOP or Single mode does the scope then go "a-ha, I don't care about update rate any more, so I'm going to make one last capture using all my available memory, just in case the user wants to do a zoom outside the display window. And I pay no penalty do doing this! Ain't I clever!"

I think what Dave concludes here sums all this thread very well. There is no justification to not filling up the whole memory (if it's not already filled) in order to have an after SINGLE/STOP zoom out.

The preferred way people use their scope is somewhat irrelevant (and something of a religion among the gurus here) to that fact.

Never crossed my mind that Siglent (and others) wouldn't implement it that way (like KS seems to do it). Maybe it is a simple change to correct that...

What is the point of having all that memory and not being able to take advantage of it? And if that's an unsurpassable obstacle, why the well do they allow the zoom out? Just to see blank screen? Or for us to validate that the scope doesn't have more samples?

Trying to fill the entire XXXM/Gpts on every single acquisition or transition from run->stop is a bad idea, its limiting the ability to capture the triggers the scope is set to (preroll/pretrigger and post trigger filling). You would end up waiting for long periods, or having triggers lost in the preroll. Deep memory is better used when it is asked for, so the user knows they might need to run a search through the capture to find all the events. For nctnico's claiming they want control over the memory depth to exactly match their application, you're proposing having even less control.

[Someone]

Gentlemen, you are ALL talking the same language!

Nico starts with zoom in and likes to be able to zoom out. The others start with zoom out and like to be able to zoom in.

It's all the same, but in reverse order.

All the rest are just details (and personal preferences or lifelong habits)!

This is from nctnico's repeated alarmism any time they can drop this "hard fail" of a workflow. Claiming silly things like its impossible to see the fast edge and capture a deep acquisition, or that there are no downsides to having longer record lengths enabled.

[Someone]

One way is as good as the other, maybe, but DSOs are designed, primarily, around zooming in.

Says who? Nobody provided any evidence that zooming out is not the way an oscilloscope works. The fact it (recording beyond the screen) is possible on many oscilloscopes suggests that those are actually designed to work this way.

They can work that way, yes. But you keep insisting that other ways to achieve the same result are completely irrelevant and not to be considered. That may be for you, but you keep bringing this extremely narrow and unusual workflow up as some general advice when its completely your imaginary construction.

If you want to bring it up, then you'll need to actually put out the reasons, constraints, and benefits of your method. This thread is full of people completely not understanding why you keep talking about this the way you do. Smells like trolling.

When put in context its an obvious obscure corner case, it requires all these simultaneously:

• slow/infrequent trigger rate (compared to the detail window being viewed)
• interesting detail at short time window
• possibly interesting detail in the larger capture (but can't rely on another trigger arriving)
• unwillingness to use a zoom window

You just draw out the discussion endlessly with distractions and nonsense. You've got a workflow that works for you, great. You'd like to see it available on more scopes, great, write to the manufacturers. But stop arguing that this workflow is somehow important for others to consider if you can't motivate us to its benefits.

[tautech]

One way is as good as the other, maybe, but DSOs are designed, primarily, around zooming in.

Says who?

Most of those that disagree with your backwards methodology of captured data analysis.

Nobody provided any evidence that zooming out is not the way an oscilloscope works. The fact it (recording beyond the screen) is possible on many oscilloscopes suggests that those are actually designed to work this way.

Says who ? Your presumption.

It seems Keysight event went through the trouble to make single acquisition mode different compared to normal acquisition mode to support zooming out after a capture by recording beyond the screen.

Actually designed that way ? I very much doubt this when it's a byproduct of the fast update rates made possible by the use of ASIC's when the majority of DSO's use ADC's and much larger memory than most ASIC based DSO's so managing the smaller capture memory in KS's is somewhat simpler to do.

The point is, zooming out is a crutch covering the far better methodology of zooming in.
While it is true many lost cost DSO's with Zoom mode only provide a 50/50 split of the display do indeed limit usability while upper entry level DSOs provide a much better split ratio where buyers of which are more accustomed to not needing so much visual reference of the primary timebase when in fact they want a larger zoomed timebase which is what they primarily work with.

No, the problem is definitely that some seem to be stuck in the idea that you should always zoom in and use exact settings.

Alternatively, others are stuck on zoom out methodology which severely limits the capability of the tool in front of you.

Even if making those settings and zoom window adds zero benefit to solving the problem at hand.

Take your blinkers off and embrace how all DSO's work.

While you entitled to work with a scope in another 'round about' way those that you may train will have a shock if they go to work for others where zooming in is the universally accepted methodology.

[Someone]

One way is as good as the other, maybe, but DSOs are designed, primarily, around zooming in. Zooming out, you are going to find yourself going against the grain. Like a left-hand thread works just as well as a right-hand thread, but insisting on using left-hand thread screws everywhere may be a problem.

The different ways to do this each have their own particular benefits, so any particular user can put their own narrow "goalposts" around that and insist one way is better. When they don't actually mention those goalposts it comes off poorly....

[EEVblog]

The point is, zooming out is a crutch covering the far better methodology of zooming in.

Err, they aren't mutually exclusive!
Every scope works by zooming in, but it seems like the likes of Keysight have thought about it and implemented it slightly different to give you a potential added benefit if you so desire it.

No, the problem is definitely that some seem to be stuck in the idea that you should always zoom in and use exact settings.

Alternatively, others are stuck on zoom out methodology which severely limits the capability of the tool in front of you.

He's just taking advantage of a feature of the scope that gives benefit to him in some cases. I don't see the problem with this and in publicising it.
I greatly doubt he uses it in every case, in fact that's not even possible.

While you entitled to work with a scope in another 'round about' way those that you may train will have a shock if they go to work for others where zooming in is the universally accepted methodology.

Why be so hostile about learning a new way to get something done?
Is it because you never knew about it before? Is it because your beloved Siglent's don't have it?
It's no different to learning say window triggering and then finding that feature isn't available on most of the scopes out there.

[Someone]

Its like some people aren't reading the whole thread and just jumping on small points, out of context.

He's just taking advantage of a feature of the scope that gives benefit to him in some cases. I don't see the problem with this and in publicising it.
I greatly doubt he uses it in every case, in fact that's not even possible.

While you entitled to work with a scope in another 'round about' way those that you may train will have a shock if they go to work for others where zooming in is the universally accepted methodology.

Why be so hostile about learning a new way to get something done?
Is it because you never knew about it before? Is it because your beloved Siglent's don't have it?
It's no different to learning say window triggering and then finding that feature isn't available on most of the scopes out there.

Because there is no substance to nctnico's endless arguments on this. Wuerstchenhund put it beautifully:

Don't get me wrong, I'm not trying to do things differently, if it works for you be my guest. But so far I have seen no data which shows any benefit of your method over the standard way, and I don't believe the need of a scope to support such a (clearly very niche) methodology should be very high on a list of recommendations.

We're waiting to have any explanation of why this method makes sense, not just some handwaving excuses around why alternatives are not fit for the overly specific and narrow use case.

[SilverSolder]

Take the Rigol DS1000z. We now established that, if you set the memory to manual then it will always record the full selected memory size, no matter what. Great, right? 

But here's the thing: on the DS1000z at least, you can't always access that data. In RUN mode, if you switch to zoom mode, you can still only zoom *in* on the signal on screen, but not zoom *out* to look at off-screen data.

On the DSO1014A (a Rigol design), with Zoom off, in Run mode, but with no triggers happening, you can use the horizontal scale & position knobs to move the displayed trace around within the offscreen captured data, and change the displayed duration. If you then turn Zoom on, you get a zoomed view of the currently displayed part of the captured data, even if it was originally off screen. The horizontal scale & position knobs change mode to operate as zoom and pan within the displayed window. Turn off Zoom and you can move to a different part of the captured data, rinse & repeat.

This could actually be quite useful: I didn't know you could do this! Do the more recent Rigols work in the same way? I'll check the X3000T as well now, I'm intrigued.

I can confirm the X3000T works in the same way, in Stop/Single mode. If there is off-screen captured data, you can use the horizontal controls in ordinary mode to bring it on screen, then use the zoom mode to zoom in on the displayed part.

One more wrinkle: you only get off-screen data from the 'magic' last capture in Stop/Single mode if the ADC sample rate is 5GHz (with one channel of each pair active). Presumably, if the sample rate is any lower, all the available memory is in use anyway.

You might get "off screen data" again if you increase the horizontal speed by 1 step compared with using 1 channel.  (That is how it works on the 54622D.)

[SilverSolder]

We're waiting to have any explanation of why this method makes sense, not just some handwaving excuses around why alternatives are not fit for the overly specific and narrow use case.

Imagine a camera with a zoom lens.  An experienced photographer does not start with the lens zoomed out to the max, and then only zooms in from that point.  Instead, they start with the lens zoomed somewhere around where their experience tell them is the best zoom factor for the kind of picture they are taking, then they trim the zoom both in and out a little bit from that point while watching the model in the viewfinder, until he/she looks "just right".  It is a fast and fluid way of working with a camera.

[EEVblog]

Because there is no substance to nctnico's endless arguments on this. Wuerstchenhund put it beautifully:

Don't get me wrong, I'm not trying to do things differently, if it works for you be my guest. But so far I have seen no data which shows any benefit of your method over the standard way, and I don't believe the need of a scope to support such a (clearly very niche) methodology should be very high on a list of recommendations.

We're waiting to have any explanation of why this method makes sense, not just some handwaving excuses around why alternatives are not fit for the overly specific and narrow use case.

I don't care about ntcnico's claims, he can defend them himself. But if you cannot see how having capture data outside of the display area could be potentially useful, then I don't know what else to say, apart from "surely the potential advantage is obvious to any experienced engineer." There is no need to give specific examples, use your imagination.

[Fungus]

Obviously with Keysight having the fastest update rate and having this feature, that's obviously not a trade off that needs to be made in basic scope design.

Keysights usually have much less memory to process than the others.

[Someone]

We're waiting to have any explanation of why this method makes sense, not just some handwaving excuses around why alternatives are not fit for the overly specific and narrow use case.

Imagine a camera with a zoom lens.  An experienced photographer does not start with the lens zoomed out to the max, and then only zooms in from that point.  Instead, they start with the lens zoomed somewhere around where their experience tell them is the best zoom factor for the kind of picture they are taking, then they trim the zoom both in and out a little bit from that point while watching the model in the viewfinder, until he/she looks "just right".  It is a fast and fluid way of working with a camera.

Again, analogies fall apart. The proposed "zoom out" is nctnico looking at an intentionally zoomed in view, with the expectation that interesting things will be captured in the larger acquisition which isn't being seen (from their prior knowledge of the scene). Nothing at all like you are describing.

Because there is no substance to nctnico's endless arguments on this. Wuerstchenhund put it beautifully:

Don't get me wrong, I'm not trying to do things differently, if it works for you be my guest. But so far I have seen no data which shows any benefit of your method over the standard way, and I don't believe the need of a scope to support such a (clearly very niche) methodology should be very high on a list of recommendations.

We're waiting to have any explanation of why this method makes sense, not just some handwaving excuses around why alternatives are not fit for the overly specific and narrow use case.

I don't care about ntcnico's claims, he can defend them himself. But if you cannot see how having capture data outside of the display area could be potentially useful, then I don't know what else to say, apart from "surely the potential advantage is obvious to any experienced engineer." There is no need to give specific examples, use your imagination.

I've tried to imagine a reason it could be better than using a zoom window, I can't see it. Having to manipulate the view is more button presses compared to having all that visible on the screen at the same time. I don't deny its useful in some circumstances, but the "arguments" for it are nonsense, and plainly untrue. So much confusion created for almost no benefit.

Just dropping "hard fail" without actually getting others to understand the reasons is the disruptive behaviour.

[maginnovision]

Having to manipulate the view is more button presses

That's exactly the point. When I do this I'm debugging something, usually real time systems where you can't alter the timing to debug. So verify one thing and check others away from the trigger after. In my case my triggers are generated by hardware. My other option would be long timebase capture, zoom in to verify item 1 and then zoom out and scroll more to check item 2. It's 1 less step. So one more step at beginning of debug session to set mem depth and then saving steps after. Timing is tight, data is slow.

[Someone]

Having to manipulate the view is more button presses

That's exactly the point. When I do this I'm debugging something, usually real time systems where you can't alter the timing to debug. So verify one thing and check others away from the trigger after. In my case my triggers are generated by hardware. My other option would be long timebase capture, zoom in to verify item 1 and then zoom out and scroll more to check item 2. It's 1 less step. So one more step at beginning of debug session to set mem depth and then saving steps after. Timing is tight, data is slow.

I'm not sure you're completely explaining the possibilities.

0) Set a wide view, zoom in later to see other things (button/knob pressing each time)
1) Set a memory depth manually, view the narrow point of interest with memory around the screen, zoom out later to see other things (slightly more setup, similar button/knob pressing each time)
2) Set a zoom view/window so both are visible at the same time on the screen (once-off setup)
....
option 185468783) use two scopes

Its a world of possibilities, none is always the best choice.

[nfmax]

Take the Rigol DS1000z. We now established that, if you set the memory to manual then it will always record the full selected memory size, no matter what. Great, right? 

But here's the thing: on the DS1000z at least, you can't always access that data. In RUN mode, if you switch to zoom mode, you can still only zoom *in* on the signal on screen, but not zoom *out* to look at off-screen data.

On the DSO1014A (a Rigol design), with Zoom off, in Run mode, but with no triggers happening, you can use the horizontal scale & position knobs to move the displayed trace around within the offscreen captured data, and change the displayed duration. If you then turn Zoom on, you get a zoomed view of the currently displayed part of the captured data, even if it was originally off screen. The horizontal scale & position knobs change mode to operate as zoom and pan within the displayed window. Turn off Zoom and you can move to a different part of the captured data, rinse & repeat.

This could actually be quite useful: I didn't know you could do this! Do the more recent Rigols work in the same way? I'll check the X3000T as well now, I'm intrigued.

I can confirm the X3000T works in the same way, in Stop/Single mode. If there is off-screen captured data, you can use the horizontal controls in ordinary mode to bring it on screen, then use the zoom mode to zoom in on the displayed part.

One more wrinkle: you only get off-screen data from the 'magic' last capture in Stop/Single mode if the ADC sample rate is 5GHz (with one channel of each pair active). Presumably, if the sample rate is any lower, all the available memory is in use anyway.

You might get "off screen data" again if you increase the horizontal speed by 1 step compared with using 1 channel.  (That is how it works on the 54622D.)

I didn't check but I think you are right, that is how Megazoom works. The guiding principles seem to be:

• Memory control is automatic, and the scope will always use as much of the available memory as it can, subject to not compromising the waveform update rate
• If memory is available, it is used first to provide the highest possible sample rate (this is what I mean by 'designed to zoom in')
• If the ADC is running at maximum speed, memory is used to provide off-screen capture (like it was in the very earliest days of DSOs with more than one screensworth of memory), but this only happens on transition to Stop/Single mode

You will only get off-screen capture at the faster X scale settings. The switchover point depends on the memory size & ADC speed. The MZ4 scopes like the X3000T have a relatively short memory and a fast ADC (4Mpoints/5gsps), so the switchover happens at much faster X scale than it did with the 54645D which @nctnico mentioned he was using when he developed his technique (1Mpoints/200Msps). With the latest MXR scope the balance is swinging back the other way - 400Mpoints/16Gsps. As soon as I can borrow one of these I will check its behaviour & report back .

However, instead of using 'spare' memory for off screen capture, I rather like the Siglent technique of keeping a history of previous acquisitions you can go back and look at - I'm always too slow pressing Stop when soemthing happens!

[nfmax]

While it is true many lost cost DSO's with Zoom mode only provide a 50/50 split of the display do indeed limit usability while upper entry level DSOs provide a much better split ratio where buyers of which are more accustomed to not needing so much visual reference of the primary timebase when in fact they want a larger zoomed timebase which is what they primarily work with.

You don't need to use the zoom function (split window view) at all if you don't want to. In the absence of triggers, or in Stop/Single mode, the horizontal scale & position controls will let you zoom in & out to the full extent of the captured data.

[Someone]

While it is true many lost cost DSO's with Zoom mode only provide a 50/50 split of the display do indeed limit usability while upper entry level DSOs provide a much better split ratio where buyers of which are more accustomed to not needing so much visual reference of the primary timebase when in fact they want a larger zoomed timebase which is what they primarily work with.

You don't need to use the zoom function (split window view) at all if you don't want to. In the absence of triggers, or in Stop/Single mode, the horizontal scale & position controls will let you zoom in & out to the full extent of the captured data.

Yes, but using a zoom window you can see both long and short time details at the same time without having to adjust or move anything. If you have more flexibility in how to allocate traces and screen space to such windows then all the better.

Both useful approaches depending on the specific circumstances.

[tautech]

While it is true many lost cost DSO's with Zoom mode only provide a 50/50 split of the display do indeed limit usability while upper entry level DSOs provide a much better split ratio where buyers of which are more accustomed to not needing so much visual reference of the primary timebase when in fact they want a larger zoomed timebase which is what they primarily work with.

You don't need to use the zoom function (split window view) at all if you don't want to.

Of course not however it gives the fullest pre and post trigger capture which in the case of a deep memory DSO could be 100+ Mpts before and after the trigger.

[nfmax]

While it is true many lost cost DSO's with Zoom mode only provide a 50/50 split of the display do indeed limit usability while upper entry level DSOs provide a much better split ratio where buyers of which are more accustomed to not needing so much visual reference of the primary timebase when in fact they want a larger zoomed timebase which is what they primarily work with.

You don't need to use the zoom function (split window view) at all if you don't want to.

Of course not however it gives the fullest pre and post trigger capture which in the case of a deep memory DSO could be 100+ Mpts before and after the trigger.

Maybe that is the case on Siglent scopes, but on InfiniVision scopes it is nothing more than a different view of the same data, after capture. You can always set the trigger delay to whatever you need, before or after the trigger event. The actual trigger event doesn't even have to be included in the capture at all, if that is what you want.