Essential Guide to Digital Signal Processing, The

C. AM and FM Radio Signals

To enhance your understanding of analog signals, it’s worth some effort to understand two types of analog signal that are “close to home,” AM and FM radio signals.

AM Radio Signals

At one time or another, everyone who reads this appendix has listened to an AM (amplitude modulation) radio, the oldest form of transmitting information using radio waves. AM is a way of embedding a low-frequency audio signal in a high-frequency radio signal. The radio signal is transmitted using an antenna, and AM radio receivers are able to extract the audio signal from the transmitted radio signal. The audio signal, in the form of a fluctuating voltage, is then amplified and applied to a loudspeaker. Let’s look at an example of those ...