:MEASure:EYE:RJ

Meas. mode:
Eye
Package License:
L-RND
Compatible waveforms:
NRZ
PAM4
Flex Apps:
FlexDCA
FlexRT
Advanced Eye RJ Commands

Command Syntax

:MEASure:EYE:RJ

Query Syntax

:MEASure:EYE:RJ?

Description

Returns an Advanced Eye Random Jitter (RJ) measurement in Eye/Mask mode. To selects the eye in an NRZ or PAM4 eye diagram on which to return the measurement, use the :MEASURE:EYE:RJ:EYE command. Since the measurement is made on an eye diagram, the pattern itself can be of any type or length, such as PRBS31. (Jitter Mode is limited to making measurements on patterns up to PRBS16.) The random and deterministic components, RJ and DJ, are determined by analyzing the crossing regions of the eye and measuring random jitter using a Q-scale approach. Separation of RJ is made in the presence of all DJ components using this method. Total Jitter (TJ) is measured at the probabilities specified by :MEASure:EYE:TJ:TJBer. To measure DJ, use the :MEASure:EYE:DJ command. To measure TJ, use the :MEASure:EYE:TJ command.

The query form of the command returns the measured RJ. If the measurement is already on, the measurement listing is moved to the top of the displayed results table.

To increase measurement accuracy, use the following steps:

  1. In Jitter Mode, measure Random Jitter (RJ) on a shorter pattern.
  2. Switch to Eye/Mask Mode
  3. Use the :MEASure:EYE:DJ:RJSTabilize and :MEASure:EYE:DJ:RJSValue commands to specify the short-pattern RJ result to be used for the DJ, RJ, and TJ measurements.
  4. Switch to a long pattern.
  5. Measure DJ, RJ, and TJ.

Requires Option 401, Advanced Eye Analysis Software license.

This Eye mode measurement can be applied to both NRZ and PAM4 waveforms.

Requires FlexDCA revision A.02.50 and above.

Measurement Identification

Avoid subtle programming errors! To ensure that the correct measurement is installed or queried, always explicitly identify a measurement when installing a measurement or querying a measured value, status, or detail. To identify a measurement, specify the measurement's source waveform (:SOURce child command). With some measurements, you may also need to specify other identifying values. Generally, when selecting a measurement using FlexDCA's GUI, if a dialog appears prompting you to select values, you should explicitly specify these values when remotely identifying the measurement. More information.

For example, to return the status of the measurement, :MEASure:EYE:RJ:

flex.write(':MEASure:EYE:RJ:SOURce CHAN1A')
if flex.query(':MEASure:EYE:RJ:STATus?') == 'CORR';
    measurement = flex.query(':MEASure:EYE:RJ?')
else:
	details = flex.query(':MEASure:EYE:RJ:STATus:DETails?')
	reason = flex.query(':MEASure:EYE:RJ:STATus:REASon?')

Child commands for measurement identification:

  • :MEASure:EYE:RJ:SOURce
  • :MEASure:EYE:RJ:RJSValue:EYE
  • :MEASure:EYE:RJ:RJSTabilize

Common Measurement Queries

Example Command Sequence

:SYSTem:MODE EYE
:MEASure:EYE:RJ:SOURce CHAN1A
:MEASure:EYE:RJ?