eye pattern
The eye diagram is a measurement method from which important parameters of data signals can be derived. The method has its name from the representation form, which corresponds to an eye.
The eye is formed by superimposing similar "1" and "0" pulse sequences and is shown on the display of an oscilloscope. Since the logic levels are ground during transmission, the square pulses loop to rounded signals. If signals of the logical "1" and signals of the logical "0" are now superimposed, a shape is formed which has a resemblance to an eye.
The representation itself can vary in the aperture of the eye and in the slurring of the signals. From the eye height and eye width, signal amplitudes and distortions in the form of delay times, bit error rates, noise and jitter can be determined.
If the eye is open, it shows good signal quality. The more open it is, the better the signal quality. If it is closed, it is no longer possible to distinguish between the 1-signals and 0-signals. Strong distortions can close the eye completely, which means that proper signal detection is no longer possible.
The measurement method with the eye diagram is used for the evaluation of digital transmission systems, of components and transmission lines.