1 眼图是什么？
在实际系统中，完全消除码间串扰是十分困难的，而码间串扰对误码率的影响目前尚无法找到数学上便于处理的统计规律，还不能进行准确计算。为了衡量基带传输系统的性能优劣，在实验室中，通常用示波器观察接收信号波形的方法来分析码间串扰和噪声对系统性能的影响，这就是眼图分析法。眼图是一系列数字信号在示波器上累积而显示的图形，它包含了丰富的信息，从眼图上可以观察出码间串扰和噪声的影响，体现了数字信号整体的特征，从而估计系统优劣程度，因而眼图分析是高速互连系统信号完整性分析的核心。另外也可以用此图形对接收滤波器的特性加以调整，以减小码间串扰，改善系统的传输性能
2 眼图的关键参数是什么？
如眼高、眼宽、眼幅度、眼交叉比、“1”电平，“0”电平，消光比，Q 因子，平均功率等
详情请参考百度百科
3 基本原理
对于含有Clock线的通信链路来说，直接用Clock的跳变沿做触发信号，然后显示Data波形，接着用余晖的方式多次叠加波形，就可以得到眼图效果
4 我的示波器能显示眼图吗？
任何实时显示示波器，都能显示眼图
Tek有个FAQ，可以解释这个问题
IS IT POSSIBLE TO DISPLAY AN EYE PATTERN ON MY OSCILLOSCOPE?
Any real-time scope can display an eye with varying degrees of clarity. The faster the scope is able to re-trigger, the clearer the eye.
To display an eye, first adjust the settings so that you are able to see one period and center it in the display. We are using a signal at a data rate of 200MHz (1 UI = 5nsec), so we will set our timebase to 1nsec/div.
Figure 1: Your data signal
Figure 2: One period of your data signal
Now adjust the position or horizontal delay so that the period being viewed is not the edge being triggered. It is usually best to center on the third or fifth UI after the trigger. In this case the third UI starts on 15nsec, so the center of the UI will be 15nsec + ½ of a UI = 17.5nsec.
Figure 3: Adjust the horizontal position or delay to the third or fifth UI
Now go into the display menu and turn on variable persistence to see both the positive and negative transitions of the period at a given unit interval.
Figure 4: Final eye diagram using persistence mode
In addition, you can use FastAcq mode or WaveformDB mode to create a color graded display of your eye.
Figure 5: Eye diagram using FastAcq mode