Amplitude Modulation

This chapter is devoted to amplitude modulation (AM). First, there is an introduction of AM, and definition of common terms such as modulation depth and modulation sensitivity based on a simple staircase message signal. Next, the chapter obtains the spectrum of an AM signal since signal spectra must be known in every communication situation to determine the required transmission bandwidth and a suitable transmission medium. It discusses the power content of an AM signal and highlights AM’s demerits in power and spectral usage. The modulator and demodulator circuits that implement the AM schemes are discussed in block diagram format. The chapter includes a discussion of the applications of AM and its variants, and the factors that dictate these applications. AM is suitable for the transmission of low‐bandwidth message signals in telecommunication applications that have low‐cost receiver implementation as a major design consideration.