Essential Guide to Digital Signal Processing, The

3. Frequency and the Spectra of Analog Signals

In the last chapter, we looked at graphical plots of how analog signals vary in value (fluctuate) as time passes. Those plots are crucial in understanding the nature of any given analog signal. However, there’s another very useful, and revealing, way to describe an analog signal. That alternate description is called the spectrum of an analog signal. Although you don’t often encounter the concept of spectra in your everyday life, signal processing people study and analyze signal spectra every day. When engineers examine (analyze) an analog signal, knowing a signal’s spectrum is as important as knowing the temperature, blood pressure, and heart rate of a patient being examined by a medical doctor. ...