mind to tell what filter is that? or if that feasible to put on DSO front end?
If you are low-pass filtering, you are removing higher harmonics. The ringing on a bandwidth limited square wave are not Gibbs ears. Just less harmonics. Because Gibbs ears are a digital signal processing artefacts from using sin x /x reconstruction, you can't get these on an analog scope because the whole digital signal processing step isn't there.
If you are low-pass filtering, you are removing higher harmonics. The ringing on a bandwidth limited square wave are not Gibbs ears. Just less harmonics. Because Gibbs ears are a digital signal processing artefacts from using sin x /x reconstruction, you can't get these on an analog scope because the whole digital signal processing step isn't there.If the ears are as you claim "a digital signal processing artefacts from using sin x /x reconstruction" please explain why they are only present on one trace.
to him the real signal that you captured is not Gibbs, since Gibbs only is the one calculated out of Sinc interpolator. however similar they look like. you do know what a pedantic and literalist are right? there is no point continue arguing round and round.
to him the real signal that you captured is not Gibbs, since Gibbs only is the one calculated out of Sinc interpolator. however similar they look like. you do know what a pedantic and literalist are right? there is no point continue arguing round and round.
Yes, that seems to be the problem. We just get circular arguments here: "No, what you show is not Gibbs, since according to my definition it is not Gibbs, but I won't tell you my definition."
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.
Does run mode superimpose multiple traces on the screen, even though Persistence is off?
Apparently it does. How many traces?
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?
I give up...
An important detail about Gibbs' phenomenon in the Fourier series of a square wave is that, although the height of the Gibbs' ear grows with the number of harmonics included, the area under the ear decreases.
So to start from end: Overshoots you see on that Siglent are result of analog Brickwall filter when you feed it with very fast signal, much faster than it's transition band is.
Why is the bandwidth highest at 2GSa/s....
"Yaigol" was fixed by a firmware update about six months after launch.
I had just discovered pictures of my Bodnarpulser on the Rigol DHO4204 which I had on loan, I put them here.
One channel active, 4GSa/s maximum sample rate, the signal looks "good".
Two channels active, 2GSa/s sample rate, the signal deforms a bit - but is "faster"(rise time)...
4 channels active, but still 1GSa/s samplerate, the signal looks a bit "blurred" in two places and the rise time becomes slower again.
Why is the bandwidth highest at 2GSa/s....
Bodnar_Single.png
Why is the bandwidth highest at 2GSa/s....i guess because it produces cleaner less jittery Gibbs (Sinc interpolation) at 2GSa/s (200pts/screen 500ps/pts)? what surprises us is why the properly bw limited scope can still produce gibbs artifact at 10x sampling rate
Why is the bandwidth highest at 2GSa/s....i guess because it produces cleaner less jittery Gibbs (Sinc interpolation) at 2GSa/s (200pts/screen 500ps/pts)? what surprises us is why the properly bw limited scope can still produce gibbs artifact at 10x sampling rateKeep in mind that any filter in the signal path with a sharp enough cut-off can introduce overshoot/ringing near edges, and if the filter happens to be a linear phase filter, then this ringing is symmetric (pre + post). This is not limited to sinc reconstruction filters, and it is not limited to undersampled signals.
In Bodnar_Dual.png (2GSa/s) I do not think that the pre- and post-ringing comes from an interpolation filter.
I have one "question"...
When there is 10ns/div and 4Gsa/s (40 sample points / div) do we really need Sin(x)/x (aka Sinc) specially when oscilloscope is also 200MHz BW.
Think about it.
(yes I know where one other oscilloscope turn Sinc off (without indicating it) when some t/div is selected...and Sinc do not give any real advantage. Even when Sinc is still selected)
Also if I design oscilloscope I will really think carefully when Sinc give some advantage and when not...
Just for thinking..
, ie capture at 4GSa/s. how amazing people can miss it!
, ie capture at 4GSa/s. how amazing most people can miss it!As you can see not everyone...
Why is the bandwidth highest at 2GSa/s....i guess because it produces cleaner less jittery Gibbs (Sinc interpolation) at 2GSa/s (200pts/screen 500ps/pts)? what surprises us is why the properly bw limited scope can still produce gibbs artifact at 10x sampling rateKeep in mind that any filter in the signal path with a sharp enough cut-off can introduce overshoot/ringing near edges, and if the filter happens to be a linear phase filter, then this ringing is symmetric (pre + post). This is not limited to sinc reconstruction filters, and it is not limited to undersampled signals.show me in any rigol DSO, or any other "better" competitive DSO from teardown photos that have this "sharp enough cut-off can introduce overshoot/ringing near edges". one member here proved that filter exists, but not for DSO. even if it is, it will not fit from teardown photos evident, we dont see fancy inductors capacitors 3x 5x parellel networks over there.
Think about it.
https://cdn.teledynelecroy.com/files/whitepapers/wp_interpolation_102203.pdf
And since the trace is pretty clean, I'm quite confident that it doesn't suffer from aliasing (at least not significantly), i.e. very likely it was properly bandwidth limited before sampling.
OTOH, I'm pretty confident, that the signal in Bodnar_Quad.png (1GSa/s) was not properly bandwidth limited before sampling and that the apparent (let me call it) "reconstruction jitter" is caused by aliasing.
In Bodnar_Dual.png (2GSa/s) I do not think that the pre- and post-ringing comes from an interpolation filter.nope! until evident provided. i've provided a few, its your turn... here's the challenge below if you miss it (on any brand scope thats capable both Sinc ON and vector/dot (Sinc OFF) mode. its like nobody understand this thread and i'm just talking to the airin fact the evident that there is no pre-ringing is just right above the 2GSa/s image, ie capture at 4GSa/s. how amazing people can miss it!