:MEASure:JITTer:JITTer:MODE

Jitter Setup Commands

Command Syntax

:MEASure:JITTerN:JITTer:MODE {TPHase | PERiod | NUINterval | DDR}

Where N identifies one of four possible jitter/noise analyses {1:4}. For example, JITTer4.

Query Syntax

:MEASure:JITTerN:JITTer:MODE?

Description

This command lets you select whether the Jitter analysis extrapolates TJ from TIE measurements or N-UI measurements:

TPHase
TIE (Phase) — The time difference between each transition and some ideal time reference. Jitter data is accumulated according to a recovered clock.
PERiod
The same as N-UI jitter with an N of 2.
NUINterval
N-Unit Interval — Like a recovered clock, N-UI is the time difference between each transition and the transition N unit intervals away from it.
Use the :MEASure:JITTer:JITTer:NUINtervals command to enter the value of N.
DDR
When an explicit clock recovery method is selected (see the :<signal>:CRECovery:MODE commands), you can select DDR for the jitter measurement.
The DDR mode supports the differences in jitter extrapolation and measurement calculations (particularly Eye Width) that are required when DQS is used as an explicit clock and measurements are made at a UI that is some distance away from the clock edge.
The advanced clock recovery :<signal>:CRECovery:ECLock:ALIGn and :<signal>:CRECovery:ECLock:DELay settings are used to identify the eye on which jitter analysis is performed.
First, note that with Centered Aligned clocks, jitter is measured on the left and right side of the eye in the middle of the eye diagram, and with Edge Aligned clocks, jitter is measured on the eye to the right of the center.
Then, to identify an eye that is a number of UI away from the clock edge, set the :<signal>:CRECovery:ECLock:DELay to a multiple of the clock period.
This way of identifying the eye on which jitter analysis is performed also aligns the eye and TIE measurement results to the jitter measurement results.
Use the :MEASure:JITTer:JITTer:NUINtervals command to enter the value of N.

N-UI and Period jitter can be performed on clock or 1/0 data waveforms only. Because N-UI and period jitter are measured from edge to edge, no clock recovery is required. However, clock recovery is used to validate the pattern length of 2 and to report the data rate.