Eye pattern

From ArticleWorld

The eye pattern effect is usually observed on the screen of a sensitive digital oscilloscope when diagnosing signals that evolve from the digital world of telecommunications. As digital signals are basically a process of “0”s and “1”s, all such signals are usually predetermined and calculated, and certainly not random. However, when observing such signals, it may seem as such that they are random; hence they are termed as “pseudorandom” signals. Such an example of this is the numbers that are generated out by a computer – it may look random, but there is an over-riding rule of process by which the computer has to arrive at the number. Hence, it is predetermined.

How to observe such a pattern

The oscilloscope’s fundamental controllers, which mainly control the vertical gain of the signal and the rate of the horizontal sweep of the signal, both assist in arriving at the eye pattern.

When the random signal, more commonly known as pseudorandom in this case, is repeatedly placed on the graph, wherein the vertical refers to the intensity and the horizontal refers to the rate or time, the ensuing pattern that we see is that of an eye pattern. It is important to realize here that digital signals are primarily a signal that consists of ups and downs, with a precise count for each and every pulse of signal that is being transmitted; since the signal is made up of “1”s and “0”s.

Relevance of such a pattern

The significance of such a signal is understood when we need to analyze the purity of a particular signal, with respect to the signal being free of distortions and interferences. The greater the signal interference, the lower the chances of viewing an eye pattern. As a result, digital signals with very bad interference will look like shut-eye or a straight line.