:MEASure:JITTer:TJ

Meas. mode:

Jitter

Package License:

L-RND

Waveform type:

NRZ

PAM4

Flex Apps:

FlexDCA

Command Syntax

:MEASure:JITTer:TJ

Query Syntax

:MEASure:JITTer:TJ?

Description

Moves the total jitter (TJ) measurement to the top of the Jitter table. Displays the measurement if it is not already shown on the table. The query form of the command returns the measured value. To select the eye in the PAM4 eye diagram on which to return the measurement, use the :MEASURE:JITTer:TJ:EYE command.

Normally, a signal's UI is equal to the sum of its eye width (EW) and total jitter (TJ):

EW _(1E−12) = 1UI −TJ _(1E−12)

However, on severely degraded PAM4 signals the tails of the jitter histograms may cross. In this case, the sum of the measured EW and TJ may not equal one UI.

PAM4 Waveform?

For PAM4 waveforms, use this recommended (identical algorithm) command instead:

:MEASure:PEYE:TJ

NRZ Waveform

PAM4 Waveform

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:JITTer:TJ:

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

Child commands for measurement identification:

:MEASure:JITTer:TJ:SOURce

Example Command Sequence

:SYSTem:MODE JITTer
:MEASure:JITTer:TJ:SOURce CHAN1A
:MEASure:JITTer:TJ?

Measurement Ready?

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

if ('CORR' in Flex.query(':MEASure:JITTer:TJ:STATus?')):
	measurement = Flex.query(':MEASure:JITTer: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:JITTer:TJ:COUNt?). The technique uses the :COUNt? common measurement query. For example,

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