:MEASure:EYE:TJ

Meas. mode:
Eye
Package License:
L-RND
Feature:
AdvEye
Waveform type:
NRZ
PAM4
Flex Apps:
FlexDCA
FlexRT
Advanced Eye TI Commands

Command Syntax

:MEASure:EYE:TJ

Query Syntax

:MEASure:EYE:TJ?

Description

Performs an Advanced Eye Total Jitter (TJ) 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:TJ: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 and the 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 RJ, use the :MEASure:EYE:RJ command.

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

To increase measurement accuracy, use RJ stabilization:

  1. In Jitter Mode, measure Random Jitter (RJ) on the signal while using a short pattern.
  2. Switch to Eye/Mask Mode
  3. Use the :MEASure:EYE:TJ:RJSTabilize and :MEASure:EYE:TJ:RJSValue commands to specify the short-pattern RJ result measured in step 1.
  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.

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:TJ:

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

Child commands for measurement identification:

  • :MEASure:EYE:TJ:SOURce
  • :MEASure:EYE:TJ:RJSValue:EYE
  • :MEASure:EYE:TJ:RJSTabilize
  • :MEASure:EYE:TJ:TJBer

Measurement Ready?

To confirm that the measurement is ready to read, you can query the measurement's status:

if ('CORR' in Flex.query(':MEASure:EYE:TJ:STATus?')):
	measurement = Flex.query(':MEASure:EYE:TJ?')

If averaging is turned on (:ACQuire:AVERaging), you can also confirm if the measurement result is ready by comparing the number of specified averages (:ACQuire:ECOunt?) versus the number of measurement sweeps that have occurred (:MEASure:EYE:TJ:COUNt?). The technique uses the :COUNt? common measurement query. For example,

if (Flex.query(':MEASure:EYE:TJ:COUNt?') >= Flex.query(':ACQuire:ECOUNt?')):
	measurement = Flex.query(':MEASure:EYE:TJ?')

You can also use an acquisition limit lest to test that a number of waveform samples, or pattern acquisitions have completed before returning a measurement. Refer to the :LTESt:ACQuire:CTYPe command.

Common Measurement Child Queries

This command supports the use of the following common measurement queries: :LOCation?, :COUNt?, :MAXimum?, :MINimum?, :MEAN?, and :SDEViation?.

Example Command Sequence

:SYSTem:MODE EYE
:MEASure:EYE:TJ:PROBability 1E-9
:MEASure:EYE:TJ:SOURce CHAN1A
:MEASure:EYE:TJ?