# Eye Amplitude

The Eye Amplitude is the difference between the logic 1 level and the logic 0 level histogram mean values of an eye diagram. This measurement is made in a section of the eye referred to as the eye window boundaries. The default value for the NRZ eye window is the central 20% of the symbol period. Two pairs of annotation labels are placed on the eye diagram. The instrument positions one pair at the one level. The other pair is placed at the zero level.

A histogram is constructed using the sampled portion of the eye diagram within the eye window. This histogram is comprised of data points from the upper and lower halves of the eye diagram and is used to determine the mean values of the logic 1 and logic 0 levels. The eye amplitude is determined as follows:

`eye amplitude = one level histogram mean − zero level histogram mean`

This measurement applies to NRZ waveforms and not to PAM waveforms.

## Configurable Measurement Parameters

This measurement is affected by the following setting (choose Measure > Thresholds...):

- Eye tab

## To measure

1. Click the measurement toolbar's Eye Meas tab.
2. Click Auto Scale in the menu bar.
3. Click the More buttons to locate the Eye Amplitude button.
4. Click the button.

## SCPI Command

`:MEASure:EYE:AMPLitude`