Oscope Dithering waveforms, logic waveforms shifting vibrating

[PrescottDan]

When waveforms or Logic signals or dithering , shifting very fast side to side, vibrating on the Oscope.

I set the Trigger level to midway of the waveform or logic signal

The Dithering/vibrating of the waveform doesn't stop

I have tried using the Trigger Holdoff, and it stabilizes the waveform or logic signals better

What is this type of problem called, what is wrong with the circuit in general?

When logic signals are noises and not clean this causes the O-scope to dither and vibrate very fast side to side the waveform?

 

[Venkadesh_M]

Oscilloscope will try to capture the input frequency and will try to generate a trigger according to it. If it is unable to predict the incoming signal, It cant show it better.

 

[PrescottDan]

When a logic signal is noise, high frequency oscillations or ripple, the Oscope's trigger voltage is hard to stable, why is that?

When a Logic signal changes every time period very slightly, the Oscope's trigger voltage is hard to be stable, why is that?

 

[Venkadesh_M]

The Trigger signal in the oscilloscope is responsible for what part of input signal has to be displayed on the screen. Which is generated with time scale setting and input signal edges, If the distance between edges in the input signals keep changing it cant be stable.

 

[PrescottDan]

If the distance between edges in the input signals keep changing it cant be stable.

But the trigger voltage is above the edges, so it should be stable

But since the Edges keep changing very slightly or has noise or ripple on the edges, the Oscope can't be stable

The Waveform is not stable but is dithering side to side very fast vibrating

what causes a Logic TTL or logic CMOS to have the edges changing slightly for every time period?

I have to use the Oscopes Trigger holdoff to make the waveform stable