Analog and Digital Signalling Essay

1246 Words 5 Pages
Part 1: General Review of Signalling
a.) Explain the fundamental differences of analog and digital signalling.
Baher (2001, p. 2) states that the natural world we live in, as well as most artificial sources, produce signals which we have grown accustomed to consider mainly of the analog type. This means that the signal f (t) is defined, somehow, for all values of the continuous variable t, and its amplitude can assume any value of a continuous range. Such a signal is referred to as an analog signal. In contrast to analog signals, other signals are defined only for discrete values of t. Thus, the independent variable t assumes discrete values.

Goleniewski (2006, p. 18) pointed out that when the signal being a continuously variable
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The fact is while traversing in the network, noise will be accumulated. This can be seen As the signal moves across the distance, it loses power and becomes impaired by factors such as moisture in the cable, dirt on a contact, and critters chewing on the cable somewhere in the network. By the time the signal arrives at the amplifier, it is not only attenuated, it is also impaired and noisy. One of the problems with a basic amplifier is that it is a dumb device. It knows only how to add power, so it takes a weak and impaired signal, adds power to it, and brings it back up to its original power level. But along with an increased signal, the amplifier passes along an increased noise level and adds its own internal noise. So in an analog network, each time a signal goes through an amplifier, it accumulates noise. After you mix the signal and the noise, you can no longer separate the tow, and, as a result, you end up with a lot of noise and very high error rates.
Goleniewski (2006, p. 20) also explain why digital signal is able to recovered after distortion from noise. Rather than use dumb amplifiers, digital networks use regenerative repeaters, also referred to as signal regenerators. As a strong, clean, digital pulse travels over a distance, it loses power, similar to an analog signal. The digital pulse, like an analog signal, is eroded by impairments in the network. But the weakened and

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