Introduction: Analog Versus Digital
We often hear that we live in a digital age. This refers to the massive adoption of computer systems within every aspect of our lives from smartphones to automobiles to household appliances. This statement also refers to the transformation that has occurr
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ribe the fundamental differences between analog and digital systems. Describe the advantages of digital systems compared to analog systems.
1.1 Differences Between Analog and Digital Systems Let’s begin by looking at signaling. In electrical systems, signals represent information that is transmitted between devices using an electrical quantity (voltage or current). An analog signal is defined as a continuous, time-varying quantity that corresponds directly to the information it represents. An example of this would be a barometric pressure sensor that outputs an electrical voltage corresponding to the pressure being measured. As the pressure goes up, so does the voltage. While the range of the input (pressure) and output (voltage) will have different spans, there is a direct mapping between the pressure and voltage. Another example would be sound striking a traditional analog microphone. Sound is a pressure wave that travels through a medium such as air. As the pressure wave strikes the diaphragm in the microphone, the diaphragm moves back and forth. Through the process of inductive coupling, this movement is converted to an electric current. The characteristics of the current signal produced (e.g., frequency and magnitude) correspond directly to the characteristics of the incoming sound wave. The current can travel down a wire and go through another system that works in the opposite manner by inductively coupling the current onto another diaphragm, which in turn moves back and forth forming a pressure wave and thus sound (i.e., a speaker or earbud). In both of these examples, the electrical signal represents the actual information that is being transmitted and is considered analog. Analog signals can be represented mathematically as a function with respect to time. In digital signaling the electrical signal itself is not directly the information it represents; instead, the information is encoded. The most common type of encoding is binary (1’s and 0’s). The 1’s and 0’s are represented by the electrical signal. The simplest form of digital signaling is to define a threshold voltage directly in the middle of the range of the electrical signal. If the signal is above this threshold, the signal is representing a 1. If the signal is below this threshold, the signal is representing a 0. This type of signaling is not considered continuous as in analog signaling; instead, it is considered to be discrete because the information is transmitted as a series of distinct values. The signal transitions between a 1 to 0 and 0 to 1 are assumed to occur instantaneously. While this is obviously impossible, for the purposes of information transmission, the values can be interpreted as a series of discrete values. This is a digital signal and is not the actual information, but rather the binary encoded representation of the original information. Digital signals are not represented using traditional mathematical functions; instead, the digital values are typically held in tables of 1’s and 0’s. # Springer Nature Switzerland AG 2019 B. J. L
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