Digital Signal Processing 101

CHAPTER 9Complex Modulation and Demodulation

We are going to take an unusual approach here. The normal explanations on modulation and demodulation are heavily based on mathematics and equations. In this chapter, we try to take an almost entirely intuitive approach, based on examples. We do not attempt to establish any mathematical foundation or to calculate performance.

Modulation is the process of taking information bits and mapping them to symbols. The sequence of symbols is then filtered to produce a baseband waveform, with the desired spectral properties. This baseband waveform or signal is then upconverted to a carrier frequency, which can be transmitted over the air, through coaxial cable, or through fiber or some other medium. The key ...