Analog and Digital Signals?
As it turns out, all signals fall into one of two major categories, analog signals and digital signals. The signals that we experience in our daily lives, the examples of sound and light signals mentioned in the previous section, are analog signals. Chapters 2 and 3 discuss analog signals in more detail.
Strangely enough, digital signals are nothing more than sequences of numbers. It’s true—sequences of numbers that can be stored in the electronic memories of computers, digital cameras, and video game machines, or recorded on CDs and DVDs. Signal processing engineers have developed a way to convert analog signals, such as a sound or light signal, into digital signals (sequences of numbers). The digital signals contain all the information of the original analog signals. In addition, signal processing engineers have also developed the means to convert a digital signal back into an analog signal (sound or light). Converting an analog signal to a digital signal and then converting the digital signal back into an analog signal doesn’t seem too useful, but that’s where digital signal processing comes in.