I have read some text about the eye pattern (or eye diagram), but I do not understand how should I read it.
The wikipedia definition of it is this one:
In telecommunication, an eye pattern, also known as an eye diagram, is an oscilloscope display in which a digital signal from a receiver is repetitively sampled and applied to the vertical input, while the data rate is used to trigger the horizontal sweep. It is so called because, for several types of coding, the pattern looks like a series of eyes between a pair of rails. It is a tool for the evaluation of the combined effects of channel noise and intersymbol interference on the performance of a baseband pulse-transmission system. It is the synchronised superposition of all possible realisations of the signal of interest viewed within a particular signaling interval.
So my first question is: how does an ideal eye pattern look like?
My second question is about how should I read it, and I think that in order to understand this I should know how it is built. For instance this page shows it in this way:
According to wikipedia, it is sufficient to make the superposition of all the signals represented in picture. I understand that the resulting signal is that shown in the last graph. But, how should I read it? Which are the advantages of analyzing it instead of the single signals properties (edges etc)?