Analog vs digital X-Y mode

[pdenisowski]

digital scope do poorly with XY because they inherently have slow update rate.   R&S has the fastest update rate with MXO4 and MXO5....but they don't yet support XY mode...and maybe their XY mode, when released, will be in SW or maybe in HW.   All digital scopes so far have XY done in SW.

I guess you'll just have to wait and see

[wolfy007]

Digital scopes dont do so bad these days, even some of the cheap ones, below are a few examples from various age groups and price range using the Dutchtronix clock (my favourite XY test), all of which show the clock fairly smoothly once you get the setting right.

[KungFuJosh]

I couldn't say how legit, but the Batronix demo video for the Magnova oscilloscope had what looked like X-Y mode that impressed me more than any other modern scope so far.

[Phil1977]

Does anyone know how much dead time the current digital scopes have in xy mode?

AFAIK modern xy mode is a spin-off of the digital phosphor technology. Many digital scopes even keep the trigger activated in XY-mode. This means, each time the trigger is activated, a snapshot of the signal on X and Y is taken and summarized to the display matrix.

But this also means that the time between the snapshots is just plotted to the screen.

In the end we have (at least) three main differences comparing analogue to digital:
- Analogue is without any dead time. XY-mode does not even need an electron beam return blank.
- Analogue has no latency or display update rate
- Analogue has no quantisation effects reducing the available resolution

Is there any modern digital scope that really addresses all these issues? At least for lower bandwidths I could imagine a continuos, triggerless data acquisition like in roll-mode. Display update rate is a matter of computing power and the relevance of quantisation is a matter of available memory - so very theoretically it may be possible, but did anyone do it?