William StallingsData and Computer Communications7th Edition

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Frequency Domain Concepts

Signal usually made up of many frequencies

Components are sine waves

Can be shown (Fourier analysis) that any signal is made up of component sine waves

Can plot frequency domain functions

Spectrum & Bandwidth


.Spectrum
range of frequencies contained in signal
.Absolute bandwidth
width of spectrum
.Effective bandwidth
Often just bandwidth
Narrow band of frequencies containing most of the energy
.DC Component
Component of zero frequency


Data Rate and Bandwidth

.Any transmission system has a limited band of frequencies

.This limits the data rate that can be carried

Analog and Digital Data


.Analog
-Continuous values within some interval
-e.g. sound, video
.Digital
-Discrete values
- e.g. text, integers