# :MEASure:EYE:EHEight:ALGorithm

NRZ Eye Height Commands

- :MEASure:EYE:EHEight
- :MEASure:EYE:EHEight:ALGorithm
- :MEASure:EYE:EHEight:FAVorite
- :MEASure:EYE:EHEight:LOCation?
- :MEASure:EYE:EHEight:SOURce
- :MEASure:EYE:EHEight:STATus?
- :MEASure:EYE:EHEight:STATus:DETails?
- :MEASure:EYE:EHEight:STATus:REASon?

## Command Syntax

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

## Query Syntax

    :MEASure:EYE:EHEight:ALGorithm?

## Description

Selects the algorithm used for the `:MEASure:EYE:EHEight` measurement.

- `MDATa` (Data) — This algorithm measures the eye height within the Eye Window specified by the Eye Height Location controls described below. The smallest eye height is reported.

- `SDEV` (Standard Deviation) — Because noise on the eye will cause the eye to close, the Standard Deviation algorithm estimates the eye height based on the mean and standard deviation of the eye top and base.

  In order to make an accurate eye height measurement, histograms are constructed to characterize both the one and zero levels and their noise levels within the eye window boundaries. The one and zero level measurements are made in a section of the eye referred to as the eye window boundaries. The default value for NRZ eye window boundaries is the central 20% of the symbol period.

  The one and zero levels are the relative means of the histograms. The noise is measured through the histograms as three standard deviations from both the one level and zero level into the eye opening.

  where:

  - Vtop = the mean voltage of the top peak of the vertical histogram.
  - σtop = the standard deviation of the top peak of the vertical histogram.
  - Vbase = the mean voltage of the bottom peak of the vertical histogram.
  - σbase = the standard deviation of the bottom peak of the vertical histogram.

Set the algorithm before turning the measurement on.