The eye diagram is created by superimposing multiple signal waveforms taken at the receiver over time, with the vertical axis representing the amplitude of the signal and the horizontal axis representing time.

Use this Demonstration to build an eye diagram by adding seven bits at a time. Use the sliders to vary the Nyquist bandwidth and the roll-off factor of the raised cosine filter.

The resulting plot forms the shape of an "eye," with the size and shape of the eye indicating the quality of the signal. A wide, well-formed eye with clear edges indicates a high-quality signal; a narrow, distorted eye with fuzzy edges indicates a poor-quality signal.

Eye diagrams are easily created in the laboratory or as part of a system simulation. This Demonstration shows the synchronized superposition of seven bits transmitted through a system with a raised cosine filter characteristic.