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082-Engineering-Mathematics-Anthony-Croft-Robert-Davison-Martin-Hargreaves-James-Flint-Edisi-5-2017

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23 Fourierseries

Contents 23.1 Introduction 722

23.2 Periodicwaveforms 723

23.3 Oddandevenfunctions 726

23.4 Orthogonalityrelationsandotherusefulidentities 732

23.5 Fourierseries 733

23.6 Half-rangeseries 745

23.7 Parseval’stheorem 748

23.8 Complexnotation 749

23.9 Frequencyresponseofalinearsystem 751

Reviewexercises23 755

23.1 INTRODUCTION

The ability to analyse waveforms of various types is an important engineering skill.

Fourieranalysisprovidesasetofmathematicaltoolswhichenabletheengineertobreak

down a wave into its various frequency components. It is then possible to predict the

effect a particular waveform may have from knowledge of the effects of its individual

frequency components. Often an engineer finds it useful to think of a signal in terms of

its frequency components rather than in terms of its time domain representation. This

alternative view is called a frequency domain representation. It is particularly useful

when trying to understand the effect of a filter on a signal. Filters are used extensively

inmanyareasofengineering.Inparticular,communicationengineersusetheminsignal

receptionequipmentforfilteringoutunwantedfrequenciesinthereceivedsignal;thatis,

removing the transmission signal to leave the audio signal. We shall begin this chapter

by reviewing the essential properties of waves before describing how breaking down

into frequency components isachieved.

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