Author Topic: Rigol DG4102 and DS1054Z skew and accumulating jitter  (Read 363 times)

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Offline RoGeorge

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Rigol DG4102 and DS1054Z skew and accumulating jitter
« on: September 26, 2017, 12:23:57 AM »
Does anybody please know/have some high resolution pics with the main clock for the DG4102 and DS1054Z, please?

I am trying to find the exact parts and their datasheets for the oscillator and PLL used in each of the DG4102 and DG1054Z, in order to understand some "jitter like" phenomena that seems to accumulate during many cycles (for example, a 0-50 ns jumping of an edge measured one second later after the trigger moment, and this is not the 5us PLL/jitter bug from a few ears ago - at 5us the edge is OK, only at very long delays after the trigger, as in hundreds of ms, the edge is jumping back and forth).

I was expecting some frequency difference between the generator and the oscilloscope's clock, so it is normal to have a time skew that increases proportional with the distance between the trigger moment and the displayed pulse.
What I was not expecting, and I don't know how to explain it, is that the jitter also increases in time.

Is it normal for the jitter to increase when the delay is longer? If yes, what determines the jitter to accumulate in time?

The test signal in the video is a repetitive pulse of 10 ns wide at each 500 ms. The pulse is generated with a Rigol DG4102 DDS. Cable is 50 Ohms impedance, with a 50 Ohms terminator at the oscilloscope side.

Smaller traces in white, orange and pink from the screen are frozen reference markers. The live signal is the yellow trace.

When delay after trigger is zero, there is no jitter. When delay is 1 second, the time skew and offset appears to be double than when the delay is 0.5 seconds.

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