:MEASure:EYE:TDEC

Meas. mode:
Eye
Package License:
L-RND
L-MFG
Waveform type:
NRZ
Flex Apps:
FlexDCA
FlexRT
TDEC Configuration Commands

Command Syntax

:MEASure:EYE:TDEC

Query Syntax

:MEASure:EYE:TDEC?

Description

Performs a TDEC measurement (Transmitter and Dispersion Eye Closure) in Eye/Mask mode. THe TDEC measurement:

  • Measures the quality of an optical transmitter with its optical link.
  • Describes the optical power penalty of the measured optical transmitter compared to an ideal transmitter. It measures the increase of optical power required for the measured optical transmitter to achieve the same eye opening of the ideal optical transmitter.
  • The lower the TDEC measurement, the higher the quality of the measured transmitter.

TDEC is often used as a replacement for a Transmission Dispersion Penalty measurement. This measurement can be used with FlexDCA's Rapid Eye feature. If pattern lock is selected, ensure that Acquire Entire Pattern is selected.

Since the measurement is made on an eye diagram, the pattern itself can be of any type or length, such as PRBS31. The query form of the command returns the measured TDEC. If the measurement is already on, the measurement listing is moved to the top of the displayed results table.

Because the TDEC measurement uses an OMA measurement to calculate TDEC, use the :MEASure:EYE:TDEC:OMA:METHod command to select the method used to obtain the OMA measurements.

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:TDEC:

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

Child commands for measurement identification:

  • :MEASure:EYE:TDEC:SOURce
  • :MEASure:EYE:TDEC:OMA:METHod
  • :MEASure:EYE:TDEC:OMA:VALue

This Eye mode measurement can be applied to PAM4 waveforms but not NRZ waveforms.

Requires FlexDCA revision A.05.00 and above.

Reference Filter and Compliance Measurements

When making TDEC compliance measurements, a reference receiver 25 Gb/s filter (effective 12.6 GHz BW) is needed and is provided in the following recommended products with Option 168:

  • 86105D Option 168 (25 Gb/s TDEC filter)
  • 86115D Option 168 (25 Gb/s TDEC filter)

To select the filter, open the optical channel setup dialog and in the Reference Filter field, select the TDEC (12.6 GHz) filter. This filter is not needed for non-compliance TDEC measurements.

Because the TDECQ and TDEC measurements call for a different bandwidth than the traditional bandwidths used by NRZ receiver mask testing, select the channel bandwidth using the :CHANnel:FSELect:BANDwidth and :CHANnel:SIRC:FBANdwidth commands, rather than the corresponding :CHANnel:FSELect:RATe and :CHANnel:SIRC:FRATe commands. When using the TDEC and TDECQ filters, the value returned by the :CHANnel:FSELect:RATe? and :CHANnel:SIRC:FRATe? queries will not correspond to the symbol rate.

Related Commands

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

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

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

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?.