Typical signals -2

Before Start

As I mentioned, SIgnal is a kind of information. Of course, it can describe most of the physical phenomena. 

For example, Figure 1.1, the pattern of variation over time in the source and capacitor voltages, Vs and Vc, that is a case of signals. Another one, Figure 1.2, the variation over time of the applied force f and the resulting automobile velocity v are also can be a signal. 

 

---

 1.1 Continous-time and Discrete-time

1. Continous-time signals(CT): The independent variable is continuous, thus these signals are defined for a continuum of values of the independent value. In other words, CT signals are able to be defined in all time values. When it is denoted by mathematical representation, x(t), the value t can have a continuous real number value.
   e.g. An analog representation of a continuously changing sound, such as an analog voltage or current, of a continuous sound captured by a microphone
   
   
   
2. Discrete-time signals(DT): Discrete-time signals are defined only at discrete times, and consequently, for these signals, the independent variable takes on only a discrete set of values. That is, DT signals are only defined at a certain point in time. such signals can be obtained by sampling at specific time intervals from CT signals. mathematically, it is represented by x[n], which is the value n must be an integer. 
   e.g. Audio played by CD player or MP3 player: Continuous analog audio signals are sampled at regular intervals and digitized. Each sample corresponds to a specific value of the discrete-time signal.
   
   Image: Each pixel value in the image corresponds to a specific value in the discrete time signal, which is arranged discretely according to the horizontal and vertical positions of the image.

 

CT signal plot

DT signal plot

 

※ Later, the relationship between the continuous signal and the discrete signal obtained through its sampling will be confirmed.