This chapter gives the reasons. It begins by raising the fundamental question of exactly what is meant by the spectrum of a signal. This, as you'll see, is actually the crux of the matter. The chapter then explains the spectrum of a pulsed signal in two quite different ways: first, in terms of a conceptually simple but powerful analytical tool, called the Fourier series, and second, in terms of what physically takes place when a radio frequency signal passes through a lossless narrowband filter. For those readers who have some familiarity with calculus, the essence of both explanations is presented in more precise, mathematical terms - the Fourier transform - at the end of the chapter.

Chapter Contents:

• Crux of the Matter
• Fourier Series
• Spectrum Explained from a Filter's Point of View
• Mathematical Explanation of the Pulsed Spectrum

Inspec keywords: Fourier series; Fourier transforms; radar signal processing; spectral analysis; filtering theory

Other keywords: pulsed spectrum unveiled; signal spectrum; calculus; lossless narrowband filter; Fourier series; Fourier transform; radio frequency signal

Subjects: Integral transforms; Filtering methods in signal processing; Radar equipment, systems and applications