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Sub: Rigol's DHO800 Oscilloscope (Gibbs Effect & Aliasing Misunderstanding)

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ebastler:

--- Quote from: Fungus on October 29, 2023, 09:10:43 am ---
--- Quote from: Mechatrommer on October 28, 2023, 10:05:44 pm ---then that probably causal... a real signal. who knows whats inside semiconductors IC?

--- End quote ---

Substrates that can predict the future?  :)

--- End quote ---

Come on, guys. A digital FIR filter (which may cause pre-ringing) cannot see into the future either when it processes a stream of digital amplitude values. It introduces a delay. The main edge appears delayed on its output, while some pre-ringing effects appear with less delay. No magic required.

gf:

--- Quote from: tautech on October 29, 2023, 08:26:15 am ---A selection, mostly dots but some vectors when we need compare.
Toggled captures between Dot and Vector mode.
Most in Stop mode but a few running, all easy to identify.
Any in Stop mode are also toggled between Dot and Vector mode.
Max at 200ps/div. Dot count in the Timebase tab.
All in Auto memory management mode.

--- End quote ---

Does run mode superimpose multiple traces on the screen, even though Persistance is off?
Apparently it does. How many traces?


--- Quote ---Please stop this BS about dot interpolation.

--- End quote ---

In run mode (e.g. ..._9.jpg) there still seems to be some interpolation going on. Not interpolation in the traditional sense, but trigger point interpolation, aligning the traces horizontally by fractional sample time offsets. Since this signal is not undersampled, the trigger point interpolation is expected to work quite well here, and apparently it does. But I wonder how well it works if the edges were undersampled?

rf-loop:
It goes (least in Siglent) just as in theory
Look Fungus... Sinc is predicting... heh

Sorry these very small real raw dots is bit difficult to see... specially after GIF animation processed.
I have used Zoom mode for get more low samplerate just for make this thing more visible and also because at this time just now I do not have suitable signal source with enough fast edges so that can demonstrate this using higher speed. But how ever it do not change math.
Acquisition and after then oscilloscope stop and visible only last single acquisition.

After then changed modes: Dots only, Sinc, Linear.

Siglent do not have this kind of linear mode where is added interpolated extra dots between real dots. Only line what connects sample dots.
Sadly there is also not display mode where real dots can highlight when Sinc or Linear interp.

In some situations it is very good if we have opportunity to turn Sinc off when ever, run time or stopped or captured to history buffer and independent of what are other settings (sadly there is also oscilloscopes where this is not possible).



Fungus:

--- Quote from: rf-loop on October 29, 2023, 10:44:55 am ---In some situations it is very good if we have opportunity to turn Sinc off ... (sadly there is also oscilloscopes where this is not possible).

--- End quote ---

Happily: I don't know any where you can't have a sample rate far above the bandwidth of the input BNC.


Fungus:
I love how everybody is busy trying to recreate a technique that was abandoned years ago in favor of sinc:

https://www.tek.com/en/documents/application-note/real-time-versus-equivalent-time-sampling

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