Over the years I’ve seen the eye pattern diagram a few times. At first I don’t understand it and I get an instructor or peer to explain it. I briefly understand, then moments later… it’s gone. If you grok how this diagram is built straight away then please forgive me. Otherwise please read on.
The eye pattern diagram is named after the eye shape in the middle of the diagram above. The purpose of the diagram is to measure the quality of the received electrical or optical signal. Put simply, the bigger the eye opening the better the signal. Before we dig deeper on the measurement we’ll examine how the eye diagram is made.