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| New Tektronix 3 Series MDO |
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| tautech:
Combine persistence with coloured intensity grading and welcome to a whole other world of glitch detection ! |
| 2N3055:
--- Quote from: snoopy on April 30, 2020, 02:11:56 am --- --- Quote from: Eric_S on April 29, 2020, 06:37:11 pm --- --- Quote from: nctnico on April 29, 2020, 04:47:42 pm --- It depends on how the traces are shown. If you take one grid and change the v/div so you can fit 4 traces you'll lose ADC resolution (and thus math precission). An alternative is to have multiple grids (split display) in which each trace can be shown at full height (IOW: using a lower v/div setting); in this case you won't lose ADC resolution. But this isn't a modern feature. --- End quote --- When people talk about the resolution of the ADC, why would they mean something to the tune of "ADC input voltage range utilization"? The concept can be important, but that is not really what I think people are talking about when they say that an Arduino Uno's got a 10bit ADC. --- End quote --- More correctly it's about dynamic range. If you have to cram 4 waveforms stacked on the screen at the one time you have to attenuate the signals to the ADC's to make them fit on the screen. So because of this you are using less dynamic range of the ADC and adding more quantization noise, thus effectively reducing the bit depth or effective number of bits ! Apparently the new Tek MSO's don't suffer from this scaling issue. Not sure about the other scope offerings. Maybe some others can enlighten us ;) cheers --- End quote --- You do realize it's a digital scope? How it's displayed has nothing to do with how it's sampled (digitized). It is not 1 to 1 mapping, it never was. Problem is that those scope manufacturers that insists scope should have "analog feel" give you no other choice to resize things on the screen that by using analog input controls. New, modern digitals scopes can zoom in and out in display domain... Attachments , signals in standard scope view(overlapped) and arranged side by side. All same input settings, same resolution and dynamic range, just different display. |
| 2N3055:
--- Quote from: tautech on April 30, 2020, 10:18:52 am ---Combine persistence with coloured intensity grading and welcome to a whole other world of glitch detection ! --- End quote --- True that!! And a suggestion to Siglent... R&S has INVERTED colour mode, that emphasizes RARE event, making them highlighted. That is very useful. Maybe something to think about as not too hard to implement (basicaly inverted pallete).. ?? |
| nctnico:
--- Quote from: 2N3055 on April 30, 2020, 10:44:46 am --- --- Quote from: tautech on April 30, 2020, 10:18:52 am ---Combine persistence with coloured intensity grading and welcome to a whole other world of glitch detection ! --- End quote --- True that!! And a suggestion to Siglent... R&S has INVERTED colour mode, that emphasizes RARE event, making them highlighted. That is very useful. --- End quote --- Correct. The inverted color mode makes glitches stand out like sore thumb. I posted some screendumps together with my RTM3004 review. |
| snoopy:
--- Quote from: 2N3055 on April 30, 2020, 09:59:36 am --- --- Quote from: snoopy on April 30, 2020, 02:03:22 am --- --- Quote from: Wuerstchenhund on April 29, 2020, 11:37:57 am --- --- Quote from: snoopy on April 29, 2020, 02:29:19 am --- --- Quote from: Wuerstchenhund on April 28, 2020, 03:22:57 pm ---InstaVu was a crutch where high update rates were achieved in a special mode using data reduction, and which made it impossible to run measurements or any other analysis on the waveform. It was only an "industry first" in a sense that no-one else implemented such a mode, very likely because of it's limitations. At around the same time, HP came out with its first MegaZoom equipped scope (HP 54645A/D, the 'D' also being the "industry first" MSO), which achieved excessive update rates in normal operation, with no limitations on measurements. And when it comes to emulating analog functionality, there simply is nothing which better resembles an analog scope than MegaZoom (if that's what you want). It's as simple as that. --- End quote --- That's not why you would use InstaVu. InstaVu was used to show up rarely occurring glitches that other scopes were blind to or may take hours sitting in front of the scope before you would capture a single glitch ! --- End quote --- So in which way is this different than any other high waveform rate technology like MegaZoom? And while your trust in InstaVu is admirable, the reality is that even at 400k wfms/s your scope is still blind >90% of the time! Even scopes like the Keysight DSO-X3000T which achieve up to 1'030'000 waveforms/s are blind 89.70% of the time. Which means there is a 9 out of 10 chance your scope will miss an event on every acquisition. Which means the *only* way to find rare events (or to make sure there are none!) is to use triggers. And this is the reason why the only market segment that actually cares about update rates is the low-end/entry-level segment, mostly because this is what serves people coming from analog scopes and who prefer analog scope derived methodology. Above that, the update rate is pretty much irrelevant, and most high end scopes achieve only comparably low trigger rates. Which, again, doesn't matter, because no-one spends $3k on a scope to search for glitches by staring at a screen. --- End quote --- Yes but you have to know what kind of glitch to trigger on otherwise you are poking around in the dark and that's if you even have the ability to trigger on it ! But you still didn't answer my question about the original megazoom acquisition rate ? Be interested to know ;) Here is a comparison between an early Tek scope and apparently still current model Keysight scope ! Not bad for a mid 90's Tek scope ;) https://youtu.be/uUM7UDWifWw?t=1809 --- End quote --- What "apparently still current model Keysight scope !", Agilent MSO6104A ? That thing is dead and gone, replaced by MSOX3000 series many moons ago... And what "magical glitches" are everybody talking about? Runts, too short pulses, dropouts, rise time anomalies ? What? All of those are well covered by triggers. This was discussed ad nauseam many times, like Someone nicely said. Using on screen persistence to capture signal anomalies can be used but has limited usability. Only information you get is that you caught something, but not when and in correlation to what. It can be used only as a proof that there are some anomalies, and hopefully give enough information for operator to devise triggering scenario to reliably capture such anomalies every time. So you can count how many are there, what is distribution and try to correlate with system state and other signals to try to find a source. Also, if you don't catch anything on screen, it is NOT a proof all is well, because you maybe didn't wait long enough... I personally use screen persistence, but first go through a set of well known triggers (rise time, pulse width, runt), that is really quick thing to do, and if those don't catch anything, i might let it run in infinite persistence mode for few hours just to be sure... You can also set mask mode, and use that too. Nobody mentions this in this context. But it is probably best way to do it. It is a built in anomaly detector, that will detect any deviation of the signal. And it will give you much more info than display persistence, because it will give you stats and confidence interval... --- End quote --- What exactly is your point ?? Tek had this functionality in the mid 90's that no other scope vendor had at the time. I have one of these scopes and have used it for that purpose many times. I don't worry about hunting through all of the triggers and trigger parameters in order to find a glitch when I can just push a single button and sit back and watch the side show on the screen ;) cheers |
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