What is an analog signal

Each of us faces electronic devices every day - this is a mobile phone, a computer for work and leisure, a TV set, a radio receiver, etc., that has become familiar. About ten years ago nobody really thought about whether a digital or analog signal is used in a particular device. However, a little time has passed and the term "digital" due to a thoughtful advertising campaign has become in many people associated with the words "good, high-quality, reliable." It is worth acknowledging that there is a certain amount of truth in this. The analog signal was used to transmit information earlier than the digital one. This is due to its simpler processing, unavailability of the infrastructure and some other reasons.

To understand what an analog signal is, it is necessary to recall the fundamentals of electrical engineering, in particular, the nature of the electric current. After all, the signal in question is, in fact, directly connected with it - it can be either direct current transmission or electromagnetic fields. For sure, everyone heard about the "famous" sinusoid.

Mentally draw a horizontal line - this is the axis of time. A continuous wave-like line is strung on it, and the height of the waves that are below and above the axis is. Next, imagine that we extend this wave-like line along the time axis. As a result, the number of waves falling at any time interval will decrease. And now "squeeze" the sinusoid - the waves began to go more often. In other words, by these actions we change the frequency. If we continue the thought experiment and "squeeze / stretch" the waves up and down with respect to the time axis, we can thereby change the amplitude. This is how an analog signal is formed.

The radio uses these two methods - FM (Frequency Modulation) and AM (Amplitude Modulation). Of course, the example given is simplified for understanding. In addition to changing the frequency and (or) amplitude, waves are subjected to other, more specific, changes. More details about this can be found on specialized websites or in the literature.

Based on the foregoing, it is possible to formulate a definition: an analog signal is a continuous, time-modulated way of transmitting information. One of its drawbacks is susceptibility to "noise pollution". Now there are mobile phones for everyone. And everyone, at least once, left the phone near the working TV or computer speakers. Those strange ordered clicks that are heard in the speakers before receiving SMS or receiving a call are known to everyone. They are electromagnetic interference, wedged into the sound reproduced by the TV or computer. Obviously, this is an undesirable phenomenon.

Guidance occurs in the conductors of the speakers. In fact, the transmitted modulated wave (analog signal) is exposed to external influences, distortions are introduced into it. Of course, in this case, a person easily selects useful data (sound) from noise, but if a signal receives logic circuits, then a number of difficulties arise. For example, it is impossible to reliably determine where the useful data is, and where the noise is.

Therefore, the analog transmission method was replaced by a digital one. The analog and digital signals are fundamentally different. The second is created as follows: the sine wave is conventionally divided into a set of points, the position of each of which is encoded by a certain sequence of pulses and gaps (no current). Usually the pulse corresponds to a logical unit, and the interval to zero (although there may be an opposite way). The receiving device decodes the received pulses and restores the original sinusoid. Obviously, such a signal is less susceptible to noise, since the decoding unit clearly distinguishes pulses. However, if the noise level is excessive, the digital signal is simply lost.