:MEASure:EYE:EWIDth:ALGorithm

Command Syntax

:MEASure:EYE:EWIDth:ALGorithm  {MDATa | SDEV}

Query Syntax

:MEASure:EYE:EWIDth:ALGorithm?

Description

Selects the algorithm used for the :MEASure:EYE:EWIDth measurement.

• MDATa (Data) — This algorithm measures the eye width within the crossings. The smallest eye width is reported.

• SDEV (Standard Deviation) — Because jitter may appear on the waveform and influence the eye opening, the Standard Deviation algorithm estimates the eye height based upon the mean and standard deviation of the crossings.

  To compute eye width using this algorithm, the crossing points of the eye are first located. Then a vertically thin measurement window is placed horizontally through the crossing points. The data within this measurement window is analyzed. This measurement window is created to be extremely small so that the width of the crossing points is not affected by the rise time and fall time of the waveform.

  The eye width is determined by measuring the noise through the histograms as 3σ (standard deviation) from both the crossing points into the eye opening.

  

  

  where:

  • t_crossing2 = the mean time value for the second crossing point.
  • σ_crossing2 = the standard deviation for the second crossing point.
  • t_crossing1 = the mean time value for the first crossing point.
  • σ_crossing1 = the standard deviation for the first crossing point.

Set the algorithm before turning the measurement on.