PAM Transition Time
The Eye mode IEEE 802.3cd PAM Transition Time measurement measures the transition time on PAM4 waveforms. You can choose to measure one of the following transitions:
- Slowest edge
- Average rising edge
- Average falling edge
By default, measurements are made on the following edges:
- Rising edges: A run of at least 5 level zeros (leading CIDs) and 6 level threes (lagging CIDs).
- Falling edge: A run of at least 5 level threes(leading CIDs) and 6 level zeros (lagging CIDs).
The transition time is measured as the waveform's edge transitions through the 20% to 80% amplitude levels between the average level zero and average level three. The average level amplitudes are measured using the same algorithm as is used for the Outer OMA measurement. You can change the default minimum leading and lagging CIDs in the PAM-N Analysis Setup dialog'sTransition Time tab.
Before making this measurement, apply a SIRC (System Impulse Response Correction) data digital filter (Option IRC on N1092A, 86105C, 86105D, 86115D, or 86116C modules). This is the same filter that is used with the TDECQ (Transmitter and Dispersion Eye Closure Quaternary) measurement. To apply SIRC correction data, use the optical channel's setup dialog box.
PAM-N Analysis Setup dialog Settings
To configure how the measurement is made, use the PAM-N Analysis Setup dialog box which provides the setting that are listed in the following table.
|Receiver Sample Timing||♦||Configures the timing for sampling the signal data for all PAM measurements in Eye/Mask mode.|
|Eye Center Location||♦||Selects the basis for determining the location of an eye's center on the waveform. This can be set at the maximum eye width or maximum eye height.|
|Eye Level Width||♦||Defines the timespan (in percentage of symbol width) over which an eye's amplitude level is measured.|
|Time Units||♦||Sets the time units for measurement: seconds or unit intervals.|
|Minimum CIDs||♦||Defines the waveform's minimum leading and laging CIDs.|