Digital signal means that the independent variable is discrete and the dependent variable is discrete. The independent variable of this signal is represented by an integer, and the dependent variable is represented by one of the finite numbers. In a computer, the size of a digital signal is usually represented by the finite bits of a binary number. For example, a binary number with a word length of 2 bits can represent four digital signals, namely 00, 0 1, 10 and11; If the signal changes in the range of-1~ 1, these four binary numbers can represent four numerical ranges, namely [- 1, -0.5], [-0.5, 0], [0.5, 1.
Analog signal refers to a signal whose information parameters are continuous within a given range. Or in a continuous time interval, the characteristic quantity representing information can be presented as a signal with any numerical value at any time.
In the process of analog signal transmission, information signals are first converted into almost identical fluctuating electrical signals (hence called "analog"), and then transmitted by wired or wireless means. After the electric signal is received, it is reduced to an information signal by the receiving equipment.
Digital signal is formed by sampling, quantization and coding on the basis of analog signal. Specifically, sampling is to obtain the sample value of the input analog signal within an appropriate time interval. Quantization is to use binary coding system to represent the measured values sampled at each moment, while coding is to arrange the binary numbers generated by T together to form a sequential pulse sequence.