ABSTRACT
The most significant difference in the digital communication systems as compared with their analog counterparts is the presence of “clock” in the digital systems. In digital systems, the events happen with the advancement of clock step by step. If the clock stops, the digital communication world would stop. The clock in the digital systems has the same function as the normal clock (or watch) in our daily life. As in our daily life, all the events such as getting up, going to the office, eating, sleeping, etc. are governed by the time of the day, which is maintained by the clock, and so it is in the world of digital communication. All the events take place, keeping steps with the equipment clock. The clock of the digital communication equipment has the same function as that of the clock of our daily life, and that is “keeping track of the time.” The only difference perhaps is that it has much smaller steps (microseconds or nanoseconds) as compared with that of the normal clock (seconds).
