Products > Test Equipment
Oscilloscope Zoom Out Quirk
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EEVblog:

--- Quote from: Someone on May 11, 2020, 03:32:29 am ---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
--- End quote ---

Glad you agree.
jemangedeslolos:
Ultimately we all know what will start the third world war.
nctnico:

--- Quote from: nfmax on May 11, 2020, 08:53:00 am ---
--- Quote from: tautech on May 11, 2020, 08:41:06 am ---
--- Quote from: nfmax on May 11, 2020, 07:50:17 am ---
--- Quote from: tautech on May 10, 2020, 11:03:20 pm ---
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.


--- End quote ---

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

--- End quote ---
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.

--- End quote ---

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.

--- End quote ---
On a DSO data is acquired around the point-of-origin (usually center) position on the screen. The trigger point is just a time offset from the point-of-origin.
2N3055:

--- Quote from: nctnico on May 11, 2020, 10:18:05 am ---
--- Quote from: nfmax on May 11, 2020, 08:53:00 am ---
--- Quote from: tautech on May 11, 2020, 08:41:06 am ---
--- Quote from: nfmax on May 11, 2020, 07:50:17 am ---
--- Quote from: tautech on May 10, 2020, 11:03:20 pm ---
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.


--- End quote ---

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

--- End quote ---
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.

--- End quote ---

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.

--- End quote ---
On a DSO data is acquired around the point-of-origin (usually center) position on the screen. The trigger point is just a time offset from the point-of-origin.

--- End quote ---

Absolutely incorrect in every way. Trigger point is THE reference point. Acquisition delay is specified from trigger point.  All else is display presentation. Acquisition engine will decide how much pre-trigger and post-trigger data will get in part based on relation of trigger point position in relation to display reference position, and it's position on screen..
Wuerstchenhund:

--- Quote from: EEVblog on May 11, 2020, 02:20:53 am ---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.

--- End quote ---

I don't think anyone argues that data outside a window which shows a narrow view of a small part of a signal is not important, and I haven't seen any comment suggesting that.

In fact, the idea that surrounding data is important is the main idea behind deep memory scopes and the standard method of "capture long and zoom in". Because knowing that things outside the original point of interest may turn out very relevant, the reason why we have large memory in mopdern scopes is so we can capture the whole sequence right from the start, and then zoom in to the areas of interest (which there might be many).

So the question is not if data outside the (narrow) window is not important, but why is the scope set in a way that important data is outside the window in the first place.

The idea that one *needs* this "zoom out" capability one can make-do, under limited conditions, on some scopes, simply because the scope was set to show a very narrow part of the actual signal when one spontaneously decides to that the rest of the signal should be examined, too, suggests to me a lack of preparation. Because especially when you're bug hunting it shouldn't really come to a surprise that parts outside that initial narrow piece of interest will become relevant. Capturing long means having every part of the signal inside view and thereby quickly available for examination in a coherent manner.

And even if you got yourself in a situation where you found your original capture was too short, instead of make-do with "zoom out" it might make a lot more sense to finally set that timebase to capture long so you avoid finding yourself in the same predicament again a few minutes later.

So I fully agree with you, data outside that narrow screen is useful, more often than not. Which raises the question why is important data outside the screen area in the first place. This off-screen data being important is even more reason to make sure right from the start to capture everything in a long acquisition.
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