Command Syntax

PAM4 Measurements

:TPRogram:SETup:MEASurements [[APOWer][, CEQ][, EDIMage][, LEVels][, LINearity][, OER][, OOMA][, OVERshoot][, PPPower][, TDEQ][, TTIMe][, TPEXcursion][, UNDershoot][, WDATa]]

Query Response

PAM4 Measurements

([APOW][, CEQ][, EDIM][, LEV][, LIN][, OER][, OOMA][, OVER][, PPP][, TDEQ][, TTIM][, TPEX][, UND][, WDAT])

Description

For a selected line in an existing Test Plan, edits the selected measurements to run and any waveform data or eye diagram image files to capture. One or more of the arguments can be included in the program message but each argument must be separated with a comma character. If no arguments are provided, all measurements are cleared (turned off). To make these selections at the time that the Test Program is defined, use the :TPRogram:SETup:MEASurements command. This command is equivalent to the Measurements settings field in the Test Program Measurement Setup dialog.

APOWer Argument Token (Average Power)

Average Power is a measure of the true average component of an optical signal. Select the units (dBm, W) with the :TPRogram:SETup:PUNits and :TPRogram:SLINe:PUNits commands.

CEQ Argument Token (Ceq Noise Gain)

PAM Ceq noise gain measurement measures the noise gain introduced by the following FlexDCA Waveform Signal Processing operators: TDECQ Equalizer, Linear Equalizer, DFE, and CTLE. Although the Ceq measurement is defined by the standard for TDECQ measurements, it can be used with any of the operators that are listed above. Ceq is expressed as:

Ceq_dB = 10 log₁₀(Noise_out / Noise_in)

EDIMage Argument Token (Eye Diagram Image)

FlexOTO saves a graphics file of the eye diagram on which the measurements were made. After your Test Program completes, click Save which is located below FlexOTO's Job Results panel to open the Save dialog. Select the dialog's Results tab and click Save. The eye diagram image will be saved in the Results zip file. You can also return an eye diagram remotely over SCPI using the :JOBS:RESults:SIMage? query. Refer to the programmer's Help for more information including an example script.

LEVels Argument Token (Linearity)

Levels measures all four amplitude levels (0, 1, 2, 3) of the PAM4 eye diagram. Select the units (dBm, W) with the :TPRogram:SETup:PUNits and :TPRogram:SLINe:PUNits commands.

LINearity Argument Token (Linearity)

Linearity is a measure of the variance in amplitude separation (distribution) between the different PAM4 levels. The linearity ratio is always equal to or less than 1.0. The value 1.0 indicates that the separations between all levels are equal. For non-compliant measurements, you can use a PRBS signal. For compliant measurements, you will need to use compliance linearity pattern that is called out in the relevant standard.

This measurement is affected by the :TPRogram:SETup:LDEFinition and :TPRogram:SLINe:LDEFinition commands.

OER Argument Token (Outer ER)

The Outer Extinction Ratio measurement measures Optical Modulation Amplitude (OMA) with a PAM4 signal's level 0 and level 3. The test requires a test pattern containing at least 6 consecutive level 0 UIs and 7 consecutive level 3 UIs. With a PRBS13Q test pattern, only the longest run of level 3 UIs and the longest run of level 0 UIs are used. For longer patterns several level 3 runs and several level 0 runs may be included. The measurement is the ratio the average level 3 value and average level 0 value.

Select the units (Decibel, Percent, or Ratio) with the :TPRogram:SETup:ERUNits and :TPRogram:SLINe:ERUNits commands.

OOMA Argument Token (Outer OMA)

PAM Outer OMA measurement measures Optical Modulation Amplitude (OMA) with a PAM4 :SETup signal's level 0 and level 3. Select the units (dBm, W) with the :TPRogram:SETup:PUNits and :TPRogram:SLINe:PUNits commands

OVERshoot Argument Token (Overshoot)

The Overshoot measurement returns a value expressed as a percentage and is defined as:

Where:

• P_max is based on a 1e-2 hit ratio, where P_max is the smallest power level that results in the number of samples above that level not exceeding the product of hit ratio and total number of observed samples. All samples are acquired in a single unit interval eye diagram. The default hit ratio is 1.0E-2.

This measurement is affected by the :TPRogram:SETup:THRatio and :TPRogram:SLINe:THRatio commands.

PPPower Argument Token (Peak-Peak Power)

The IEEE 802.3cu compatible Peak-Peak Power measurement is reported in Watts or dBm. Select the units (dBm, W) with the :TPRogram:SETup:PUNits and :TPRogram:SLINe:PUNits commands

TDEQ Argument Token (TDECQ)

The TDECQ (Transmitter and Dispersion Eye Closure Quaternary) measurement measures the quality of an optical transmitter with its optical link. TDECQ is 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 as the ideal optical transmitter. The lower the TDECQ measurement, the higher the quality of the measured transmitter.

This measurement is affected by the :TPRogram:SETup:TMPReset, :TPRogram:SLINe:TMPReset, :TPRogram:SETup:TEPReset, and :TPRogram:SLINe:TEPReset commands.

TTIMe Argument Token (Transition Time)

The Transition Time measures the transition time based on the Slowest edge, average Rising edge, or average Falling edge as selected by this dialog's Target Transition setting. The default setting is Slowest.

This measurement is affected by the :TPRogram:SETup:TRANsition and :TPRogram:SLINe:TRANsition commands.

TPEXcursion Argument Token (Tx Power Excursion)

The Transmitter Power excursion (TPE) measurement for PAM4 signals is IEEE 802.3cu compatible and is given by the following equation:

where:

• P_max is based on a 1e-2 hit ratio, where P_max is the smallest power level that results in the number of samples above that level not exceeding the product of hit ratio and total number of observed samples. All samples are acquired in a single unit interval eye diagram.
• P_min is based on a 1e-2 hit ratio, where P_min is the largest power level that results in the number of samples below that level not exceeding the product of hit ratio and total number of observed samples. All samples are acquired in a single unit interval eye diagram.
• P_avg is the average power of the signal.

This measurement is affected by the :TPRogram:SETup:THRatio and :TPRogram:SLINe:THRatio commands.

Select the units (dBm, W) with the :TPRogram:SETup:PUNits and :TPRogram:SLINe:PUNits commands.

UNDershoot Argument Token (Undershoot)

The Undershoot measurement returns a value expressed as a percentage and is defined as:

Where:

• P_min is based on a 1e-2 hit ratio, where P_min is the largest power level that results in the number of samples below that level not exceeding the product of hit ratio and total number of observed samples. All samples are acquired in a single unit interval eye diagram. The default hit ratio is 1.0E-2.

This measurement is affected by the :TPRogram:SETup:THRatio and :TPRogram:SLINe:THRatio commands.

WDATa Argument Token (Waveform Data)

FlexOTO saves the waveform data in a FlexDCA compatible internal-format waveform file XML file (.wfmx). This file can be imported into a FlexDCA waveform memory. The file starts with an ASCII XML header followed by binary waveform data. The file includes vertical and horizontal scaling parameters of the waveform. Therefore, when you load the waveform into a FlexDCA's waveform memory, you can still perform automatic measurements and use markers on that waveform. The internal format is binary, so you can not directly display the file contents in a word processing or spreadsheet program. However, you can convert an internal format file to a text file (.txt) for use in a spreadsheet or word processing program, by loading the file into FlexDCA's waveform memory and then re-saving the waveform in either Y-values format or XY-values format.

After your Test Program completes, click Save which is located below FlexOTO's Job Results panel to open the Save dialog. Select the dialog's Results tab and click Save. The waveform data will be saved in the Results zip file.

Example Command

station.write(:TPRogram:SLINe:FIXTure "DUT Fixture 2"')  # Turns off all lanes
station.write(:TPRogram:SLINe:FIXTure "DUT Fixture 2", LANE1,LANE2')  # Turns on Lanes 1 and 2
station.write(':TPRogram:SETup:FORMat PAM4')
station.write(:TPRogram:SLINe:MEASurements OOMA,APOWer,EDIMage')
station.write(:TPRogram:SLINe:PUNits WATT')