Products > Test Equipment
Siglent SDS800 Zoom out question (problem?)
electr_peter:
--- Quote from: tautech on October 05, 2024, 09:05:49 am ---Okay, so you like the Keyshite way, I get that, so show us a $440 model with that capability ?
--- End quote ---
Once again, you try to denigrate Keysight ideas. If other scope has some refined features that Siglent doesn't have, they automatically are not useful/worth the cost/redundant/etc. according to you, got it.
electr_peter:
@2N3055, your explanation of how Keysight works is on point. However, you seem to go a bit further and imply that "proponents of zoom out" feature also suggest to incorporate it in analysis process which they do not. I am not in any way suggest you or anybody to use zoom out as a process (never had), just that in some cases this feature can be useful.
--- Quote from: 2N3055 on October 05, 2024, 10:21:55 am ---
--- Quote from: electr_peter on October 05, 2024, 08:39:05 am ---
--- Quote from: tautech on October 05, 2024, 08:06:45 am ---Why engage the brain when the processing power in the modern DSO is far more powerful ? :-//
--- End quote ---
Why put blinders on and mentally limit available options from scope suite? :-//
Anyway, user chooses process that is most suitable for application at hand, I not arguing what one "should use".
--- End quote ---
I agree. Let's not put blinders on.
So why are you ignoring that Keysight does not "capture outside the screen".
--- End quote ---
Because it does in RUN/STOP mode under specific conditions as you described yourself (example 1). In example 2 it did try to capture outside display (as in example 2), but did not find valid trigger and reverted back to the last in display capture already in memory. Otherwise, it would have captured as in example 1.
--- Quote ---What you see on the screen is separate, later capture from separate trigger than the one that made you press Stop.
...
When you press stop it waits for next trigger event and captures some other, random part of waveform, uncorrelated to what was on the screen when you press Stop.
--- End quote ---
Can you explain what do you expect scope to display when you press STOP? Because statement above is correct practically everytime when looking at signals in fasttime bases. With fast timebases and triggers 100s of times a second even pressing STOP button has all sorts of user/scope delays which results in something on the screen that may or may not be similar to what was on screen in RUN mode. With rare triggers it is a bit more clear what to expect to happen, but still anything can be shown depending on changes in signal.
If signal is jumping around all over the shop like crazy, separate snapshots in SINGLE/STOP mode will also jump around like crazy (and having 1 snapshot in such cases obviously is not enough). What else can scope do? I am really not sure what your angle here is :-//
Are you implying that more memory is better? Sure, but that is a separate thing.
--- Quote ---So basically, to observe the neighborhood of some event of the screen, it as useful as simply changing timebase to whatever you want to look at while scope is still in the RUN mode and then STOP.
That is exactly what Keysight does, but automatically. I guess it is good if you cannot be bothered to change timebase then stop instead of just single lazy STOP.
--- End quote ---
Yes, it is equivalent. But it is improvement nonetheless compared to typical scope operation even if you think it is "lazy". Again, it is just a feature, but it is not an instruction how one should use a scope.
--- Quote ---But result is the same, you get some random uncorrelated time in signal when trigger activates. If that is OK for you because signal is monotonic and auto repetitive to such degree that it does not matter where you look, then what is the point of "looking around". It is all going to be the same. Perfect replica. Once you put whole period on screen, all others are the same.
If signal is highly agile, than Keysight is useless. Dangerous I may say. It will show you false data somewhere else than what you were looking at...
It is trick, and the scope lies to you. literally.
--- End quote ---
Once again, I still don't understand your point. If signal is jumping around and you get single fixed capture, of course you can miss changing behavior. It is up to the user to get enough captures at proper times bases. STOP/SINGLE mode is just doing exactly what it says, there is no lying here. You can call Keysight way a trick, cunning plan or cheating, but it is not lying.
"you get some random uncorrelated time in signal when trigger activates" - this definition applies to all trigger captures as well, so :-//
2N3055:
--- Quote from: electr_peter on October 05, 2024, 12:37:22 pm ---
--- Quote from: tautech on October 05, 2024, 09:05:49 am ---Okay, so you like the Keyshite way, I get that, so show us a $440 model with that capability ?
--- End quote ---
Once again, you try to denigrate Keysight ideas. If other scope has some refined features that Siglent doesn't have, they automatically are not useful/worth the cost/redundant/etc. according to you, got it.
--- End quote ---
Keysight does NOT do what you claim it does.
After stopping, you DO NOT have insight into what was around event that was on screen when you pressed STOP.
It does not "zoom out". It takes separate, later capture, at some completely different time, and shows you what was around that later event.
It does that only on timebases less than 20µs/div and can show up to 400µs altogether. If you have MSO active, it is half of that.
Worst part is that people keep insisting it "zooms out". It does not. It simply does this: If you are at timebases of less than 20µs/div, it will keep capturing only screen width, trigger to trigger. If you then press stop, on it's own it will change timebase to equivalent of 40µ/div, wait for trigger and then take a separate Single capture and then Stop.
This is absolute functional equivalent to manually changing timebase to something else and pressing Stop.
Both ways you will get some random capture later. With exception that Keysight does that and pretend it to be something else. And you have one less step. But always only 400/200µs worth of data. While on other scopes with deep memory (which includes Keysights with deep memory, mind you) you can capture 100ms if you like.
Only way to guarantee that scope will capture definite time interval around some part of waveform is to deliberately instruct scope what, where and how much.
You can do that in two ways:
- By using Nico's method of setting manual memory length (on scopes that support it) by calculating times from combination of memory size and sample rate, and manually position screen to some detail inside that buffer. Then you do stop and by using time base and horizontal position you travel back and forth and inspect. CON is It requires mental math, but PRO, it makes good use of full screen for details.
- By using long timebase and zoom function. You setup long capture with timebase, set everything on screen, and then use zoom to travel back and forth. CON is zoom mode partitions screen and detail is not so large on screen. PRO is that setup is simple, intuitive and WISIWIG. You always have visual map of whole capture and your position where are you looking into detail.
And you are wrong. In this case it is Siglent (and LeCroy) that has sophisticated features. Like always running History mode, where you can see last 100s or 1000s triggers. With timestamp. With full analysis on each. With 4 maths channels with arbitrary formula input. And 20-125X more memory
On SDS300xHD, in history mode you can then go find one of the thousands, save that as a memory, create math channel that subtracts memory from current history capture and show you difference.
2N3055:
--- Quote from: electr_peter on October 05, 2024, 12:57:10 pm ---@2N3055, your explanation of how Keysight works is on point. However, you seem to go a bit further and imply that "proponents of zoom out" feature also suggest to incorporate it in analysis process which they do not. I am not in any way suggest you or anybody to use zoom out as a process (never had), just that in some cases this feature can be useful.
--- Quote from: 2N3055 on October 05, 2024, 10:21:55 am ---
--- Quote from: electr_peter on October 05, 2024, 08:39:05 am ---
--- Quote from: tautech on October 05, 2024, 08:06:45 am ---Why engage the brain when the processing power in the modern DSO is far more powerful ? :-//
--- End quote ---
Why put blinders on and mentally limit available options from scope suite? :-//
Anyway, user chooses process that is most suitable for application at hand, I not arguing what one "should use".
--- End quote ---
I agree. Let's not put blinders on.
So why are you ignoring that Keysight does not "capture outside the screen".
--- End quote ---
Because it does in RUN/STOP mode under specific conditions as you described yourself (example 1). In example 2 it did try to capture outside display (as in example 2), but did not find valid trigger and reverted back to the last in display capture already in memory. Otherwise, it would have captured as in example 1.
--- Quote ---What you see on the screen is separate, later capture from separate trigger than the one that made you press Stop.
...
When you press stop it waits for next trigger event and captures some other, random part of waveform, uncorrelated to what was on the screen when you press Stop.
--- End quote ---
Can you explain what do you expect scope to display when you press STOP? Because statement above is correct practically everytime when looking at signals in fasttime bases. With fast timebases and triggers 100s of times a second even pressing STOP button has all sorts of user/scope delays which results in something on the screen that may or may not be similar to what was on screen in RUN mode. With rare triggers it is a bit more clear what to expect to happen, but still anything can be shown depending on changes in signal.
If signal is jumping around all over the shop like crazy, separate snapshots in SINGLE/STOP mode will also jump around like crazy (and having 1 snapshot in such cases obviously is not enough). What else can scope do? I am really not sure what your angle here is :-//
Are you implying that more memory is better? Sure, but that is a separate thing.
--- Quote ---So basically, to observe the neighborhood of some event of the screen, it as useful as simply changing timebase to whatever you want to look at while scope is still in the RUN mode and then STOP.
That is exactly what Keysight does, but automatically. I guess it is good if you cannot be bothered to change timebase then stop instead of just single lazy STOP.
--- End quote ---
Yes, it is equivalent. But it is improvement nonetheless compared to typical scope operation even if you think it is "lazy". Again, it is just a feature, but it is not an instruction how one should use a scope.
--- Quote ---But result is the same, you get some random uncorrelated time in signal when trigger activates. If that is OK for you because signal is monotonic and auto repetitive to such degree that it does not matter where you look, then what is the point of "looking around". It is all going to be the same. Perfect replica. Once you put whole period on screen, all others are the same.
If signal is highly agile, than Keysight is useless. Dangerous I may say. It will show you false data somewhere else than what you were looking at...
It is trick, and the scope lies to you. literally.
--- End quote ---
Once again, I still don't understand your point. If signal is jumping around and you get single fixed capture, of course you can miss changing behavior. It is up to the user to get enough captures at proper times bases. STOP/SINGLE mode is just doing exactly what it says, there is no lying here. You can call Keysight way a trick, cunning plan or cheating, but it is not lying.
"you get some random uncorrelated time in signal when trigger activates" - this definition applies to all trigger captures as well, so :-//
--- End quote ---
It is simple. Only way to capture changing signal and be able to do it at least partially coherent is long memory. And that is actually not a separate issue.
Simply, you DON'T look at the signal at the fastest timebase if you want data around. On a scope with large memory you can keep fastest SAMPLE rate down to 10s of ms/div. All the details are there, same as if you were at 1 ns/div.
And use zoom mode to look at the detail. Or stop and traverse data with timebase and horizontal pos.
As you said yourself, any scope does the same if you do one more manual step. So yes it is simply a shortcut, a "lazy" way. Scopes that don't have that shortcut have same capability. It is used differently. But it is wrong to imply that by using Keysight you get something others cannot accomplish. Of course they can, by using different UI. Which on different scopes, UI and workflow differences are much greater than this detail.
electr_peter:
--- Quote from: 2N3055 on October 05, 2024, 01:30:47 pm ---Keysight does NOT do what you claim it does.
After stopping, you DO NOT have insight into what was around event that was on screen when you pressed STOP.
It does not "zoom out". It takes separate, later capture, at some completely different time, and shows you what was around that later event.
--- End quote ---
Keysight does what it claims. "last capture in RUN mode" is earlier in time than "capture in STOP mode" aspect is more or less true with all scopes in STOP mode. That may be different if scope captured everything with 0 blind time at max sample rate or have duplicated capture data path, but we are not there yet in normal scopes.
Which capture out of 1000s of traces in RUN mode does your scope STOP on? Are you really are sure which one exactly? With fast trigger events this is a pointless question. With slow trigger events it is more clear if you need this clarity.
--- Quote ---Both ways you will get some random capture later. With exception that Keysight does that and pretend it to be something else. And you have one less step.
--- End quote ---
"random capture later" applies to all trigger captures. Also you have much faster waveform update rate while getting more memory in STOP mode.
--- Quote ---And you are wrong. In this case it is Siglent (and LeCroy) that has sophisticated features.
--- End quote ---
I said refined features that Keysight has (and others do not have) which you did not prove wrong. Sure, modern Siglent/Lecroy are good scopes with many features and big memory, no wonder these are very popular considering cost.
--- Quote from: 2N3055 on October 05, 2024, 01:46:22 pm ---As you said yourself, any scope does the same if you do one more manual step. So yes it is simply a shortcut, a "lazy" way. Scopes that don't have that shortcut have same capability. It is used differently. But it is wrong to imply that by using Keysight you get something others cannot accomplish. Of course they can, by using different UI.
--- End quote ---
Where did I say other scopes cannot accomplish something? Do you see a difference between a feature/shortcut (in a narrow sense) and ability to accomplish something (in a wider sense)? Keysight has useful feature (another way to accomplish something a bit faster) which others do not have.
I think I get it now - this Keysight "zoom out" bashing is covert criticism that Keysight InfiniVision memory is lacking compared to competition. Then just say it straight and not in these roundabout ways. "Zoom out" feature is alive and well (independent of memory size), it just has to face unfair criticism for some reason.
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