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For example, the dithering of samples that HP/Agilent introduced. It seems to me that by dithering the samples slightly, you end up with more fine grained results that would otherwise have to come from using a much higher sample rate - but the "punishment" is probably a longer acquisition time, as the dithered samples slowly build up the complete picture?
ETS (Equivalent Time Sampling) resolution is only limited by the ability to time the samples, given a repetitive signal. I think earlier Rigols even had it, but they've dropped it as a feature, which I'm guessing is because of how the trigger is implemented now. You still get a sort of random dot-walk effect that will give you a picture similar to an old ETS scope but this is not controlled and is due to the varied relationship between the trigger point and the sampling points.
I don't think the dithering that HP did (still does?) is the same at ETS?
If you have a constant e.g. 200MSa/s, and you can dither the samples e.g. by 5 discrete steps, you end up with a "slow" 1GSa/s.
Maybe that effectively is actually the same as equivalent time sampling, just done by random steps instead of one long linear sequence?
Just for fun..
When oscilloscope works with decimated samples many or some DPO scopes can do Sequential Acquisition Random Interleaving (SARI)
This is used signal.. 20ns pulse repeating 1.87MHz.
Next images scope have forced to low sampling speed using decimation and zoomed window for demonstrate aliasing and other things more easy.
Look carefully sampling speed and risetime etc things...
Sinc post interpolation on.
Linear post interpolation on.
It have many times specially by LeCroy and also others said that this is sometimes better for this kind of signals. No gibbs etc...
No interpolation, just pure samples and nothing else (SARI).
In live screen it looks better due to human eye-brain things etc.
If you turn Siglent scope to slow ack mode (what is also useful in some special cases, it works like conventional DSO) mode SARI is not possible.
Other signal, other case.
Specially in these gif animations live screen it looks better due to human eye-brain things etc. Also gif animation amount of frames and timing is not like in IRL where it looks better but this may give some idea for least some because here in forum are also beginners and scope many have many features, settings and adjusments. Not only these what we most use, example always Sinc on without even thinking if this is always best mode.
Signal 45MHz some kind of "squarewave" and things far over 25MHz Nyquist... (this is not very normal how we setup scope but it was more easy to demonstrate with tools what was just available at this time moment) But with this aliasing and not aliasing... just example about SARI with decimated samplerates. Aliasing, no aliasing. Just because random interleave. Of course this works only for enough continuous waveforms.
Nothing but aliasing
Sari and no aliasing
Even simple cheap tools have many features what user need be familiar. Too many times we use example scopes like "this is how I always have done" instead of thinking if it is always wise. Many hate dots mode but do not overlook it even when it is best in some situations, do not too much think polished nice picture, think what you need know about signal and nothing else. Modern DPO scopes can do lot of better than conventional DSO