An analog signal is a signal whose analog information (such as sound information, image information, etc.) changes. However, digital signals are different. They are sampled, quantized and encoded to form digital signals (also called pulse signals).
First, the signal source works differently.
1. Digital signals deal with discrete signals, and digital signals are usually represented by 1 and 0.
2. Analog signals deal with continuous signals, which are generally represented by continuously changing electromagnetic waves or continuously changing signal voltages.
Second, the output mode is different.
1. Analog signals are generally transmitted through traditional transmission lines (such as telephone network and cable TV network).
2. When the digital signal is expressed by intermittent voltage or optical pulse, it is generally necessary to connect the two communication parties with twisted pair and optical fiber medium to transmit the signal from one node to another.
Third, the communication characteristics are different.
Characteristics of analog communication: In order to improve the signal-to-noise ratio, it is necessary to amplify the attenuated transmission signal in time during signal transmission, and the noise inevitably superimposed on the signal during transmission is also amplified. With the increase of transmission distance, the noise accumulates more and more, which leads to the serious deterioration of transmission quality.
Characteristics of digital communication: Because the amplitude of digital signal is a finite discrete value (usually two amplitudes), although it will be disturbed by noise in the transmission process, when the signal-to-noise ratio deteriorates to a certain extent, the decision regeneration method is adopted at an appropriate distance to generate the same digital signal as the original sender without noise interference, so long-distance high-quality transmission can be realized.
Baidu Encyclopedia-Analog Signal
Baidu Encyclopedia-Digital Signal