What is Jitter in Fiber Optic Telecom Systems?
www.fiberoptics4sale.com Hello, everyone. This is Colin from Fiber Optics For Sale. In this video, I will explain what is jitter in fiber optic telecom systems, why jitter is bad, what causes jitter, and three types of jitter testing. So let’s get started. What is jitter? Let’s look at this illustration first. The solid line signal is the ideal clock. It has a perfect period. The dashed line signal is jittered clock. We can see that the rising edges of the jittered clock have a displacement from the ideal clock. The timing difference is marked as J1, J2, J3, J4, and J5. This phenomenon of timing displacement from its ideal position is called jitter. The amount of jitter varies periodically. The jitter period is the interval between two times of maximum effect or minimum effect. Jitter frequency is jitter period’s inverse. According to ITU-T G.810, jitter frequencies below 10 Hz is called wander, and at and above 10 Hz is called jitter. The bottom figure shows the plot of the relative displacement versus time, this is called the jitter’s time function. So why is jitter bad for a fiber optic communication system? Here is an eye diagram that shows the distortions caused by jitter. In order to accurately determine whether a given bit is a one or a zero, the signal should be sampled at the point where the vertical eye opening is maximum. This decision point is set by the recovered clock signal from the data bits. But a jitter causes this decision point to move away from the …
