Digital Signal Processing, 10th Edition

Introduction

A signal is the medium carrying information, transmitted by a source to a receiver. In other words, a signal is the vehicle of intelligence in systems. It transports commands in control and remote-control equipment; it carries data such as information, spoken words, or images across networks. It is particularly fragile and needs to be handled with a great deal of care. Signal processing is applied in order to extract information, alter the message being carried, or adapt the signal to the transmission techniques being used. It is here that digital techniques come into play. Indeed, if we imagine substituting the signal with a set of numbers, representing its value or amplitude at carefully chosen times, then its processing, even in the most elaborate of forms, boils down to a sequence of logical and arithmetical operations on that set of numbers, committing the results to memory.

A continuous analog signal is converted into a digital signal by sensors which act on readings, or directly in the devices producing or receiving the signal. The operations taking place in the wake of that conversion are carried out by digital computers, tasked or programmed to perform the sequence of operations by which the desired processing is defined.

Before introducing the content of each chapter of this book, it is wise to precisely define the processing of which we speak here.

Digital signal processing refers to the set of operations, arithmetic calculations, and number manipulations, ...