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Oscilloscope Zoom Out Quirk
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SparkyFX:
A few years back I struggled to understand why scopes don't allow this full use of sample memory, as trigger processing should not affect it (effectively wasting the memory). Slower update rate might be a point, but if you consider that the use of more channels will limit the amount of data before and after triggering greatly because the memory organization will be affected, the usefulness of zooming out would vary a lot for each timebase - or cripple the sample memory per channel.

Therefore I rather like the segmented memory approach.
nctnico:

--- Quote from: SparkyFX on June 11, 2020, 05:53:43 am ---A few years back I struggled to understand why scopes don't allow this full use of sample memory, as trigger processing should not affect it (effectively wasting the memory). Slower update rate might be a point, but if you consider that the use of more channels will limit the amount of data before and after triggering greatly because the memory organization will be affected, the usefulness of zooming out would vary a lot for each timebase - or cripple the sample memory per channel.

--- End quote ---
It doesn't matter at all. Sampling memory is per channel anyway and the memory is used as a circular buffer. There are no downsides.
nctnico:

--- Quote from: jjoonathan on June 11, 2020, 02:01:13 am ---The question is "what does the scope do by default when it has extra memory beyond what's used by the configured acquisition." The three answers I've seen are "waste it," "extend the acquisition," and "hold on to past acquisitions." Wasting it is dumb, extending the acquisition is nice, but history is my favorite:

Maybe if I were doing a lot of serial decoding and running into partial packets my preference would flip.

--- End quote ---
The latter is the point: it greatly depends on the use case. Depending on what you are doing history mode (aka circular segmented recording) can be a huge waste as well because the memory can be put to better use as 1 long record for a measurement. In the grand scheme of things I have need for all modes (history, long memory, short memory, segmented recording) so when I buy an oscilloscope I make sure it can do all.
EEVblog:

--- Quote from: nctnico on June 11, 2020, 07:20:33 am ---The latter is the point: it greatly depends on the use case. Depending on what you are doing history mode (aka circular segmented recording) can be a huge waste as well because the memory can be put to better use as 1 long record for a measurement. In the grand scheme of things I have need for all modes (history, long memory, short memory, segmented recording) so when I buy an oscilloscope I make sure it can do all.
--- End quote ---

And that's the thing. For a scope not to offer the full memory for a single capture even when deliberately selected (without using a convoluted dual timebase system) is just silly.
The user needs to be able to chose how that memory is used, and Siglent/Lecroy/Picoscope are seemingly the only ones crippled in this regard.
nfmax:
A question for anyone with a scope that has the 'history' mode:

Does changing the settings between triggers, e.g. changing vertical or horizontal scale, or enabling an additional channel, clear the history buffer? If not, do such changes get reflected in the on-screen display of the settings, when reviewing history?
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