Analog vs. Digital

In a world full of Analog signals and waves, some engineers got mad and decided to transcend to a more certain level of true and false, or in digital terms, 1 and 0. Sound, temperature, light intensity, power and most of the natural phenomena we interact with on daily basis can all be represented by analog signals, or to be more specific, have a continuous curve relation between its dependent and independent variables. But what if we decided to draw a line? Between what we consider is acceptable and not acceptable? A barrier that separates what we can work with and what we can’t accept at all? Now that is digital.


If we were to construct a circuit consisting of a sensor, a deciding mind and an acting hand to measure the room temperature and to turn on the AC if the temperature dropped under a certain level that makes a person uncomfortable, we will have to break down this process of “deciding” into some smaller processes.


First, the “sensing” process, in which an analog sensor is responsible for measuring the temperature and turning it into an electrical signal that travels through wires or transmitted through a transmitter to the next phase.


Second, the “converting” process, in which an analog signal is converted into a digital one –by the means of an analog to digital converter– to be dealt with in a more certain manner, drawing the barrier of the “least value I can accept” and assigning a “1” output to any input value of the analog signal above this barrier and a “0” output to any input value beneath it, or vice versa depending on your design, and sending the output to the next phase.


Third, the “deciding mind” process, designing a circuit to receive a digital input of 1’s and 0’s, the input then undergoes a series of procedures and designed protocols with programmable or non-programmable mechanisms just for the sake of assigning the proper output for every input, and then it sends an output also of 1’s and 0’s to the next process.


Finally, the “acting arm” process, in which it executes the order it receives from the previous phase, whether it’s a simple on/off order or a complex one of arithmetic operations, a series of on/offs of several peripherals, a simple display of certain messages or even handing it to another “converting” process to convert the signal again into an analog one.


Any system consists of these three major processes: the “sensing, deciding and acting” processes. In some cases, other processes are needed like: converting, feedback, or others. But the difference between analog and digital still might not be clear, and for so, here are some quick tips:


Analog circuits operate on continuous valued signals, or analog signals, but digital circuits operate on signals that only exist at two levels, the 1’s and 0’s, or the binary number system. Analog circuits are more difficult to design than digital circuits since each component has to send a continuous output value for every continuous input value, the possibilities in this case are infinite. Analog circuits require less converting processes than digital circuits for the aforementioned reason. And also for the aforementioned reason there is less or no loss of information, opposing that of the digital circuits. And most importantly, Analog circuits are mostly custom made and lack flexibility, but digital circuits have high degree of flexibility.


In the end, we depend on analog and digital circuits equally, and can’t live with only one of them. So let’s be thankful for nature for their analog, and for engineers for getting mad and creating digital.





This Post is posted by Abdelrahman El-Adawy

An IEEE AlexSB Volunteer, R&P Committee.

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