# How do I make an Eye Height measurement without the Sigma 3 factor?

### 問題：

How do I make an Eye Height measurement without the Sigma 3 factor?

### 答案：

The algorithm for Eye Height measurements includes Sigma3 for both the High and Low measurements. This results in a lower Eye Height measurement than when cursors are used. To derive the Eye Height value without Sigma 3 (or Sigma 0), follow the steps below:

Step 1: Create a High measurement. Turn on Gating and set the gates to the center 1% of the eye pattern. Set the HiLow to Min/Max.

Step 2: Create a Low measurement. Turn on Gating and set the gates to the center 1% of the eye diagram. Set HiLow set to Min/Max

Step 3: Create a Pk-Pk Noise measurement on High part of the eye pattern. In the Region section, you can specify either High or Low for where to take the measurement.

Step 4: Create a Pk-Pk Noise on the Low part of the eye pattern.

Step 5: Crate a Math waveform. Define the waveform: (Meas1-(1*Meas3))-(Meas2+(1*Meas4)).

Step 6: Create a Mean measurement for the Math waveform created in Step 5.