Communications Blockset

Eye Diagrams

An eye diagram is a simple and convenient tool for studying the effects of intersymbol interference and other channel impairments in digital transmission. When this blockset constructs an eye diagram, it plots the received signal against time on a fixed-interval axis. At the end of the fixed interval, it wraps around to the beginning of the time axis. Thus the diagram consists of many overlapping curves. One way to use an eye diagram is to look for the place where the "eye" is most widely opened, and use that point as the decision point when demapping a demodulated signal to recover a digital message.

The two blocks, Continuous-Time Eye and Scatter Diagrams and Discrete-Time Eye and Scatter Diagrams, both produce eye diagrams. One processes continuous-time signals and the other processes discrete-time signals. The blocks also differ in the way you determine the decision timing: the Continuous-Time Eye and Scatter Diagrams block draws a vertical line to indicate a decision every time a trigger signal has a rising edge, whereas the Discrete-Time Eye and Scatter Diagrams block draws a similar line periodically according to a mask parameter.

An example appears in Example: Using Eye and Scatter Diagrams.

Error Statistics

Scatter Diagrams