Products > Test Equipment
Oscilloscope Zoom Out Quirk
tautech:
--- Quote from: rsjsouza on March 06, 2021, 12:33:28 pm ---
--- Quote from: tautech on March 06, 2021, 08:34:07 am ---No SDS2104X Plus left ...customers have them all so out comes zoom on a SDS5104X.......
What's not to like......still an 8" display of which half is still usable.
Cluttered display ? :-//
--- End quote ---
In my opinion, yes. I have less screen area to what I really want to see from the waveform itself, not the entire capture. Sure, a Pico will never have this issue, but an 8'' screen (just like my DS4014) this is not good.
--- End quote ---
You may have misunderstood. :-//
10" native display but in Zoom mode 8" of corner to corner usable display still remains where in this image only half is used by 3 traces including the decode display.
This is a pile of screen real estate in which to add a further trace, apply Maths, Histograms, Statistics, Measurements etc any of which can be positioned on the remaining half of the display to ones liking.
A stopped/captured waveform record is where the power of a DSO can then be applied to magnify amplitude, Pan or Search the whole record with a range of parameters to ensure the waveform integrity meets requirements of which for SDS5000X we have the minimum 125 Mpts at this primary timebase setting. SDS2000X Plus will show a minimum 100 Mpts record with the same scope settings.
These are relatively new and powerful scopes that like any new device/tool/component takes time to comprehend and properly utilize in a manner we may have not used or fully understood when compared to previous experience.
nctnico:
@Tautech: please stop making a fool out of yourself by pretending everyone but you is stupid. DSOs have had zoom mode and math since the late 80's. Oscilloscope users are well aware that it exists; there is nothing new or special about zoom mode and math these days.
2N3055:
--- Quote from: rsjsouza on March 06, 2021, 12:33:28 pm ---
Sinisa, that is where you lose me. No question about the benefits or characteristics of the Auto setting, but another is the fact that in a Rigol I can set a memory depth and the oscilloscope will obey my command. That is not what is seen in Dave's video: Siglent will size it according to what it thinks it is better.
And no, I don't need to do "mental math and paying attention that they all sit together" either.
Otherwise, I have been in lenghty interface and ease-of-use discussions to know these things are hard to convince if there is not a very clear benefit one way or another.
--- End quote ---
Rafael, it is probably me not being able to explain well. Rigol comes by default in Auto, and I met more than few people that keep using it only in Auto, because for interactive work it is better, than having to think about capture memory, and still have scope work as fast as possible. If you want to understand how Siglent memory works, put your Rigol in Auto memory and observe how it behaves.
That is what I wanted to explain. I also repeated many times that Rigol is better in this regard, because you can choose fixed memory too. Which you use sometimes also, which is OK, because sometimes it can be useful. That is fine.
About mental math, that is maybe debatable. Why? Because, when you set 14 Mpts memory depth, how long SPI (or any other event) sequence can you get with it ? And by long I mean how much time you get in total? 10 ms, 20 ms, 330 ms ?
Please see attached excel table and verify if I calculated wrong...
In short , if you're looking at short timebase and you don't need fast refresh, you will have a lot data captured off the screen.
But that is because your scope have huge 140(70)MPts memory. Nicos scope has 80(40)MPts, so you loose some advantage.
If you have 10 Mpoint scope, it looks less good. But still usable.
Problem is that, after hundreds of messages, I managed to make Nico say what is his main use for it. What he said it was capturing long data on serial buses, while looking at very short part of that capture that has some event or packet of interest. He keeps scope in RUN mode (not Single), and if he sees the event (error, or whatever is of interest) he manually stops the scope (events are sparse, so there is time to react) and then can move inspect whole capture for details. Captures are quite long, on order of 0,1 -2 seconds, done on low sample rates.
To achieve that, you cannot run too fast timebase, because at 80Mpts you need 50Msps/sec to achieve 1,6 sec, for instance. How do you setup your scope to do that?
Regards,
Someone:
--- Quote from: Fungus on March 06, 2021, 09:22:22 am ---
--- Quote from: 2N3055 on March 06, 2021, 09:05:58 am ---LeCroy, Siglent, Picoscope, Rigol (by default AUTO strategy), R&S (by default AUTO strategy), Keysight Infiniivision (Run mode), Micsig (by default AUTO strategy) and all others that have AUTO memory mode use that same method of only grabbing only amount of data that is equivalent to length of screen in current timebase.
--- End quote ---
Nope. All of them grab the amount of data which is the current memory depth. That can easily be more data than fits on screen.
--- End quote ---
2N3055 is correct, and provided the specific modes which cause this to occur. The "current" memory depth on many scopes varies and can't always be set explicitly. This entire thread is that extremely narrow point.
--- Quote from: Fungus on March 06, 2021, 09:22:22 am ---
--- Quote from: 2N3055 on March 06, 2021, 09:05:58 am ---They all do it to minimize amount of data taken in every trigger to get faster reacting scope and keep sampling rate high to avoid aliasing.
--- End quote ---
Are you saying Keysights are slowed down and/or suffer aliasing because of this? My Rigol certainly wasn't.
--- End quote ---
Why auto? Lets go way back in time:
https://www.eevblog.com/forum/testgear/new-tektronix-tbs2000-oscilloscopes/msg1283038/#msg1283038
Thats a Rigol (the specific brand you asked for) causing aliasing or slow update rates if the user selects an inappropriate memory depth. On older Tek scopes there wasn't an auto memory setting and it was quite annoying to go into the menus to adjust the memory depth every time you wanted to change capture lengths (some debugging does well to look at small details and then larger ones, back and forth). Keysight megazoom scopes? They don't let the user set any of that and always maintain the highest update rate (in run mode, in single trigger they fill the full depth), aliasing isn't an issue with them as they have very effective filtering to prevent it.
2N3055:
--- Quote from: Someone on March 06, 2021, 09:41:00 pm --- 2N3055 is correct, and provided the specific modes which cause this to occur. The "current" memory depth on many scopes varies and can't always be set explicitly. This entire thread is that extremely narrow point.
--- End quote ---
Thank you for summarizing that better than I ever could.
--- Quote from: Someone on March 06, 2021, 09:41:00 pm ---Thats a Rigol (the specific brand you asked for) causing aliasing or slow update rates if the user selects an inappropriate memory depth. On older Tek scopes there wasn't an auto memory setting and it was quite annoying to go into the menus to adjust the memory depth every time you wanted to change capture lengths (some debugging does well to look at small details and then larger ones, back and forth). Keysight megazoom scopes? They don't let the user set any of that and always maintain the highest update rate (in run mode, in single trigger they fill the full depth), aliasing isn't an issue with them as they have very effective filtering to prevent it.
--- End quote ---
EDIT. deleted.
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