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## 1.1 Time/frequency representation of digital signals

#### It will become apparent after reading the early chapters of this book that the performance of a digital communications link is constrained by two primary factors: channel bandwidth and system noise. In order to understand fully the interaction between system data/symbol rate, modulation type, pulse shape and channel bandwidth, a grasp of the frequency content of various types of time domain data signals is key. The mathematical tools used to map between the time and frequency domain are most commonly the Fourier Series representation (for periodic signals) and the Fourier transform (for general periodic and non-periodic signals). Other mapping techniques exist, such as wavelets, but are beyond the scope of this book. |