Chapter 16

DSP and Digital Filters

Walt Kester

16.1 Origins of Real-World Signals and Their Units of Measurement

Let’s first look at a few key concepts and definitions required to lay the groundwork for things to come.

Webster’s New Collegiate Dictionary defines a signal as “a detectable (or measurable) physical quantity or impulse (as voltage, current, or magnetic field strength) by which messages or information can be transmitted.” Key to this definition are the words: detectable, physical quantity, and information.

By their very nature, signals are analog, whether DC, AC, digital levels, or pulses. It is customary, however, to differentiate between analog and digital signals in the following manner: Analog (or real-world) variables in nature include ...

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