| Products > Test Equipment |
| Oscilloscope Zoom Out Quirk |
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| tv84:
--- Quote from: nctnico on May 10, 2020, 12:22:49 pm ---Come to think of it: it makes no sense needing to use zoom mode to have all the memory available. I already told the oscilloscope to use a certain amount of memory. --- End quote --- You're contradicting yourself. You have to choose: fill all the memory or don't fill all the memory. If not, you'll be defending Siglent's way in a hurry... |
| nctnico:
--- Quote from: tv84 on May 10, 2020, 12:37:12 pm --- --- Quote from: nctnico on May 10, 2020, 12:22:49 pm ---Come to think of it: it makes no sense needing to use zoom mode to have all the memory available. I already told the oscilloscope to use a certain amount of memory. --- End quote --- You're contradicting yourself. You have to choose: fill all the memory or don't fill all the memory. If not, you'll be defending Siglent's way in a hurry... --- End quote --- I'm not contradicting myself. Needing to use zoom made in order to make the oscilloscope use the memory depth I set is making the same setting twice. |
| nctnico:
--- Quote from: Wuerstchenhund on May 10, 2020, 12:24:23 pm ---I agree, this is just a case of a poor UI on a particular scope, not a problem that's inherent to zoom as a function. --- End quote --- It is not; I'm using all DSOs like this. Like several others you are trying to argue less is somehow more while grasping at straws no thicker than a hair trying to ridcule me. Just give up. |
| EEVblog:
--- Quote from: Someone on May 10, 2020, 11:39:21 am --- --- Quote from: EEVblog on May 10, 2020, 11:27:43 am --- --- Quote from: Someone on May 10, 2020, 11:16:42 am ---The argument against always having full memory depth for single captures is what do you do when the pre trigger buffer isn't full yet, but the user pressed single? Throw away possibly the only trigger? --- End quote --- Ah, THAT'S the magic in the capture architecture design! This just triggered my memory! (pun of the week, surely?) I independently solved this in my DSOA Mk3 design back in 1998 with 7200 FIFO's. https://alternatezone.com/electronics/files/dsoamk3.txt --- End quote --- Not sure you solved it: --- Quote ---The RAM FILL period is required in order to allow the RAM to be at least half filled with data. This is to ensure that the data the PC reads back will always contain half pre-trigger information and half post-trigger information. If a trigger was to occur before the RAM is half filled, then we would have an indeterminable number of pre-trigger samples (if any at all). --- End quote --- Thats the same problem of what to do when the pre-trigger buffer isn't filled yet. With modern scopes having Mpts and Gpts of memory the pretirgger period can be substantial if you always have to fill it even when you are on a shorter timebase/memory setting. --- End quote --- Yeah but you only have to pre-fill memory once after the uses presses the START button. In most usage cases and non-slow timebases that's practically an instant, and is actually the price you pay when you have defined the (default) horizontal trigger position to be center memory. There is no way around doing it once unless you copied your sample memory to display/plot memory and then continued to sample in the background. That would be a huge design trade-off for so little gain. |
| nfmax:
--- Quote from: EEVblog on May 10, 2020, 01:03:26 pm --- --- Quote from: Someone on May 10, 2020, 11:39:21 am --- --- Quote from: EEVblog on May 10, 2020, 11:27:43 am --- --- Quote from: Someone on May 10, 2020, 11:16:42 am ---The argument against always having full memory depth for single captures is what do you do when the pre trigger buffer isn't full yet, but the user pressed single? Throw away possibly the only trigger? --- End quote --- Ah, THAT'S the magic in the capture architecture design! This just triggered my memory! (pun of the week, surely?) I independently solved this in my DSOA Mk3 design back in 1998 with 7200 FIFO's. https://alternatezone.com/electronics/files/dsoamk3.txt --- End quote --- Not sure you solved it: --- Quote ---The RAM FILL period is required in order to allow the RAM to be at least half filled with data. This is to ensure that the data the PC reads back will always contain half pre-trigger information and half post-trigger information. If a trigger was to occur before the RAM is half filled, then we would have an indeterminable number of pre-trigger samples (if any at all). --- End quote --- Thats the same problem of what to do when the pre-trigger buffer isn't filled yet. With modern scopes having Mpts and Gpts of memory the pretirgger period can be substantial if you always have to fill it even when you are on a shorter timebase/memory setting. --- End quote --- Yeah but you only have to pre-fill memory once after the uses presses the START button. In most usage cases and non-slow timebases that's practically an instant, and is actually the price you pay when you have defined the (default) horizontal trigger position to be center memory. There is no way around doing it once unless you copied your sample memory to display/plot memory and then continued to sample in the background. That would be a huge design trade-off for so little gain. --- End quote --- Or use two swinging buffers, even in Single mode. But that halves your maximum record length, which seems like a poor choice. |
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