Ethernet Renderers jitter measurements

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jespera

  • Jr. Member
  • Posts: 6
Re: Ethernet Renderers jitter measurements
« Reply #20 on: 24 Oct 2018, 08:00 pm »

As far as I know overshoot and ringing is due to the limited bandwidth.
Actually, due to the gibbs phenomenon, the overshoot will not disappear
even with unlimited bandwidth. But most of what we see on the flat part
of the square wave looks like noise and not ringing. And that was what
I was interested in...

Quite a good video though ...

Jesper

audioengr

Re: Ethernet Renderers jitter measurements
« Reply #21 on: 25 Oct 2018, 06:02 pm »
Sorry for pestering you with stupid questions. Here are some more:

What does b/w of 7GHz mean?

Bandwidth of 7GHz allows one to see all of the high-frequency in the signal.

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What is the sampling freq of the scope?

50GHz

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Is there any way of reducing the noise on the squares?

The noise on the square-waves is of no consequence.  The only thing that matters is the rising edges.

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Would the use of
discrete components (transistors, tubes, chokes, etc) rather than chips help?

You could probably filter out the noise by using a slower responding regulator and maybe slower logic family, but the jitter would increase dramatically because the risetime would slow.

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Do you think it would be audible?

Yes, it would cause smearing of the image due to increased jitter.

Steve N.

audioengr

Re: Ethernet Renderers jitter measurements
« Reply #22 on: 25 Oct 2018, 06:05 pm »
Steve can answer far better than I, but while some of the 'noise' on the square wave trace might actually be noise, most of what you're seeing is just the nature of a band-limited signal.

Agreed.

Steve N.