:MEASure:EYE:TI

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:TI

Query Syntax

:MEASure:EYE:TI?

Description

Performs an Advanced Eye Total Interference (TI) measurement in Eye/Mask mode on NRZ or PAM4 signals. TI is the amount of vertical interference on a signal that is due to deterministic causes. Total Interference (TI) is the width of the one (or zero) level distribution at a low probability or symbol error rate (BER). By default the measurement is made at a BER of 1E-12 (1 x 10–12), which is a probability of occurrence of less than 1 part per trillion. Use the :MEASure:EYE:TI:TIBer command to change the BER setting to any value between 1E-1 to 1E-18. 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.) If you experience difficulties measuring a PAM4 signal, confirm that the signal-type setting is set to PAM4 with the :CHANnel:SIGNal:TYPE command. The random and deterministic components, RI and RN, can be measured using the :MEASure:EYE:RN and :MEASure:EYE:DI commands. If the measurement is already on, the measurement listing is moved to the top of the displayed results table.

To increase measurement accuracy, use TI stabilization:

  1. In Jitter Mode, measure Random Noise (TI) on the signal while using a short pattern.
  2. Switch to Eye/Mask Mode
  3. Use the :MEASure:EYE:TI:RNSTabilize to turn on RN stabilization and :MEASure:EYE:TI:RNSValue commands to specify the short-pattern RJ result measured in step 1.
  4. Switch to a long pattern.
  5. Measure DI, RN, and TI.

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.05.30 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:TI:

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

Child commands for measurement identification:

  • :MEASure:EYE:TI:SOURce
  • :MEASure:EYE:TI:RNSTabilize
  • :MEASure:EYE:TI:TIBer
  • :MEASure:EYE:TI:RNSValue:LEVel1
  • :MEASure:EYE:TI:RNSValue:LEVel0

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:TI:STATus?')):
	measurement = Flex.query(':MEASure:EYE:TI?')

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:TI:COUNt?). The technique uses the :COUNt? common measurement query. For example,

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

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:TI:SOURce CHAN1A
:MEASure:EYE:TI?