:MEASure:EYE:ERATio
Command Syntax
:MEASure:EYE:ERATio
Query Syntax
:MEASure:EYE:ERATio?
Description
Moves the extinction ratio measurement to the top of the Results table. Displays the measurement if it is not already shown on the table. The query form of the command returns the measured value. Extinction ratio is the ratio of the one level and the zero level of an eye diagram of an optical signal. Sources can be any displayed waveform, color-grade memory, or function. For example, CHAN1A, CGMemory1, or FUNCtion1. Use the :MEASure:EBOundary:LEFT, :MEASure:EBOundary:RIGHt, and :MEASure:EBOundary:DEFault commands to change the eye boundary settings.
This Eye mode measurement can be applied to NRZ waveforms but not PAM4 waveforms.
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:ERATio:
flex.write(':MEASure:EYE:ERATio:SOURce CHAN1A')
if flex.query(':MEASure:EYE:ERATio:STATus?') == 'CORR';
measurement = flex.query(':MEASure:EYE:ERATio?')
else:
details = flex.query(':MEASure:EYE:ERATio:STATus:DETails?')
reason = flex.query(':MEASure:EYE:ERATio:STATus:REASon?')
Child commands for measurement identification:
:MEASure:EYE:ERATio:SOURce:MEASure:EYE:ERATio:UNITs
Extinction-Ratio Correction Factors
Use extinction-ratio correction factors to compensate for the frequency response of a module's internal reference receiver filter for an optical channel. The 86105C module has recommended correction factors for each of the module's reference receiver filters. When you select an 86105C filter, the recommended correction factor is automatically selected for the extinction-ratio measurement. Correction factors are also useful when an external photodetector is connected to an electrical channel.
Use the :MEASure:ERATio:CHANnel:CFACtor command to apply extinction ratio correction factors for NRZ waveforms. Whenever a correction factor value is applied to a measurement, the entered value is displayed using the ERCF annotation on the measurement Results panel (for example, ERCF: 0.2%).
Example Command Sequence
:MEASure:EYE:ERATio:SOURce CHAN1A :MEASure:EYE:ERATio :MEASure:EYE:ERATio?
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:ERATio:STATus?')):
measurement = Flex.query(':MEASure:EYE:ERATio?')
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:ERATio:COUNt?). The technique uses the :COUNt? common measurement query. For example,
if (Flex.query(':MEASure:EYE:ERATio:COUNt?') >= Flex.query(':ACQuire:ECOUNt?')):
measurement = Flex.query(':MEASure:EYE:ERATio?')
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?.