| Products > Test Equipment |
| Oscilloscope Zoom Out Quirk |
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| nctnico:
--- Quote from: tautech on May 10, 2020, 10:00:31 am --- --- Quote from: nctnico on May 10, 2020, 09:49:25 am --- --- Quote from: tautech on May 10, 2020, 09:45:08 am ---Or we could just start the car in gear because pressing of the clutch is just another further unnecessary operation ! :horse: --- End quote --- That is another advantage of an automatic gearbox; you don't have to press the clutch pedal. Good point! --- End quote --- ::) Another thing you haven't properly thought through. You can't start an auto in gear and once started you need to select D after pressing the foot brake and the guy that started the manual in gear is already way off down the road ! --- End quote --- But you don't need your left foot at all. But let's stop discussing car gears. The point is that it makes no sense trying to argue that less is somehow more. In the real world less is just less. Use your time to point Siglent to this thread and add this feature. Likely it is 3 lines of extra code. Maybe they can beat Dave to making a video showing how it doesn't work on Siglent scopes but it does work on Rigol's 8) |
| Martin72:
--- Quote ---Use your time to point Siglent to this thread and add this feature. Likely it is 3 lines of extra code. --- End quote --- If it were that simple, why not. Having is better than needing. But there must be a reason why they haven“t done this so far. |
| tv84:
So, after all, if Siglent introduces "nico's way" all is settled? :phew: Finally I'm starting to see the light! :D Thanks guys. |
| nfmax:
--- Quote from: Wuerstchenhund on May 08, 2020, 09:18:13 am ---Keep in mind this is *not* "zooming out"as having your scope in normal mode and just changing the timebase so you can see more of the signal, which again works on every scope. It's really about if a scope can record beyond its screen on very short timebases when the memory is set accordingly, which is only visible in a single acquisition. --- End quote --- Older DSOs used to behave like this. I just checked using the first DSO I ever bought with my own money - an Agilent DSO1014A (actually made by Rigol, but that's not relevant). It has a stunning 20,000 points of memory per channel (in 2-channel mode) and a 2Gsps ADC (again in 2 channel mode). Furthermore, it has the Tek-inspired memory-use display above the main window. This shows what is on the screen as a fraction of the whole memory. NewFile0.png shows the situation for X scales of 500ns/div and longer. Data is captured beyond the screen limits, and in Single or Stop mode you can increase the X scale by just less than two ranges, i.e. you get a full screen trace at 1us/div but only 8 divisions' worth at 2us/div. If the X scale is reduced to 50ns/div you get the situation shown in NewFile1. The screen occupies a smaller fraction of the total memory, and you can now increase the X scale to 500ns/div while maintaining a full display. On entry-level DSOs of this era and before, there is no way of varying the amount of memory used, as it was so small to begin with. Waveform update rate is limited by the acquisition engine (to 400 wfm/s), not by the number samples captured at each trigger. At higher price points, the amount of memory increased, but the ADC rate not so much. Hence, for shorter X scales (limited by the ADC sample rate), the amount of 'off-screen' memory may also be increased. At longer X scales (= 'slower timebases') the increased memory is used instead to increase the ADC sample rate. Thus short X scales allow you to zoom out more than you can zoom in, and the other way round for long X scales It was perhaps using a scope from this era (like, e.g. the Agilent 54645) that @nctnico developed his 'zooming out' technique. It worked because, fortuitously, the X scale setting needed to show the details of the data frame was in the 'zooming out' optimised range. The subsequent increases in ADC sample rate, and more particularly the waveform update rate wars, changed this situation again. With user-controlled memory depth, the oscilloscope designer still has to choose between using additional allocated memory to increase the ADC sample rate, thereby allowing more levels of zooming in, or to increase the off-screen capture length, allowing more levels of zooming out. Because the latter option also reduces the headline waveform update rate (because each waveform is longer), it tended to lose out. Maybe this is why @nctnico so disparages waveform update rate as a parameter - because it goes against his way of using the scope? |
| EEVblog:
--- Quote from: nctnico on May 10, 2020, 09:40:59 am ---And I don't get how fast waveform updates suddenly become relevant in this thread; capturing beyond the screen has no downsides. --- End quote --- It's only relevant if designing in this feature was done at the sacrifice of update rate in the design. 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. |
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