What is a device that can convert analog signals to digital signals and vice versa?

The device that can convert analog signals and digital signals to and from each other is a modem; a modem is the abbreviation of modulator and demodulator. It is a computer hardware device that can translate the digital signal of the computer into a signal that can be used by ordinary telephones. Analog signals transmitted over a line, and these analog signals can be received by another modem at the other end of the line and translated into a language that the computer can understand.

The operating environment of this tutorial: Windows 10 system, DELL G3 computer.

What is the device that can convert analog signals and digital signals to each other?

The device that can convert analog signals and digital signals to each other is a modem

Modem, short for modulator and demodulator, is a type of computer hardware that translates a computer's digital signals into analog signals that can be transmitted along ordinary telephone lines, and these analog signals can be transmitted by another modem at the other end of the line. Receive and translate it into a language that the computer can understand. This simple process completes communication between two computers.

Brief introduction

Modem is the abbreviation of Modulator and Demodulator. It is called modem in Chinese. According to the homophony of Modem, A "cat" as it is affectionately called, is an electronic device capable of performing the modulation and demodulation functions required for communication. Generally consists of modulator and demodulator. At the sending end, the digital signal generated by the computer's serial port is modulated into an analog signal that can be transmitted through the telephone line; at the receiving end, the modem converts the analog signal input into the computer into a corresponding digital signal and sends it to the computer interface. In personal computers, modems are often used to exchange data and programs with other computers, as well as to access online information service programs, etc.

The so-called modulation is to convert digital signals into analog signals transmitted on telephone lines; demodulation is to convert analog signals into digital signals. Collectively called a modem.

The English name for modem is MODEM, and its function is the "translator" of analog signals and digital signals. There are two types of electronic signals, one is "analog signal" and the other is "digital signal". The telephone lines we use transmit analog signals, while the PCs transmit digital signals. So when you want to connect your computer to the Internet through a phone line, you must use a modem to "translate" two different signals. After connecting to the Internet, when the PC sends information to the Internet, since the telephone line transmits analog signals, a modem must be used to "translate" the digital signals into analog signals before they can be transmitted to the Internet. This process is called "modulation" ". When the PC obtains information from the Internet, since the information transmitted from the Internet through the telephone line are all analog signals, if the PC wants to understand them, it must also use the "translation" of the modem. This process is called "demodulation" . Generally speaking, it is called "modulation and demodulation".

Basic Principle

The average voice frequency range is 300-3400Hz. In order to transmit the voice signal in the ordinary telephone system, a certain bandwidth is allocated to it on the line. , the international standard takes 4KHz as the frequency bandwidth occupied by a standard voice channel. During this transmission process: the voice signal is input at a frequency of 300-3400Hz. The sender's telephone converts the voice signal into an analog signal. This analog signal is changed through a frequency division multiplexer so that it can be transmitted simultaneously on the line. When the multi-channel analog signal reaches the receiving end, it goes through a frequency decoding process to restore it to the original analog signal in the frequency range, and then the receiving telephone converts the analog signal into a sound signal.

The information in the computer is a digital signal composed of "0" and "1", but what is transmitted on the telephone line can only be an analog electrical signal. Using analog channels to transmit digital signals without taking any measures will inevitably lead to large errors (distortion). Therefore, when transmitting data on ordinary telephone networks, the digital signals must be converted into the audio frequency spectrum required by the original design of the telephone network (i.e. 300Hz). -3400Hz).

Modulation is to use baseband pulses to control a certain parameter of the carrier waveform to form a signal suitable for line transmission.

Demodulation is to remove the carrier from the analog signal transformed by the modulator and restore it to the original baseband digital signal when the modulated signal reaches the receiving end.

Using a modem, you can also convert audio signals into higher frequency signals and convert higher frequency signals into audio signals. Therefore, another purpose of modulation is to facilitate line multiplexing in order to improve line utilization. Based on the three main parameters of the carrier signal, the modulation methods can be divided into three types: amplitude modulation, frequency modulation and phase modulation.

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