What is a Modem? Please tell us more about it, thank you

Modem (tiáozhìjiětiáoqì) is modem

It can convert digital signals into analog signals and transmit them on the network, and can also convert the received analog signals into digital signals. Since most personal computers are connected to the computer network through the public ** network, the above conversion needs to be carried out through a modem.

It is a device for signal conversion between the computer and the first line, which is composed of two parts, a modulator and a demodulator, the modulator is a device that modulates the digital signal of the computer (such as files, etc.) into a sound signal that can be transmitted on the first line, and at the receiving end, the demodulator converts the sound signal into a digital signal that the computer can receive. Data communication between computers can be realized through a modem and a ** line.

At present, there are two main types of modems: built-in and external.

The built-in modem is actually a computer's expansion card, which can be used by plugging into an expansion slot in the computer, and it does not occupy the computer's serial port. Its connection is quite simple, insert the ** cable connector into the "line" socket on the card, and the other interface "phone" on the card is connected to the ** machine, when the modem is not used at all, the ** machine is not affected at all.

The external modem is a cassette device placed outside the computer, it needs to occupy a serial port of the computer, and it also needs to be connected to a separate power supply to work, there are several status indicators on the external modem panel, which can be convenient for you to monitor the communication status of the modem, and the external modem is easy to install and disassemble, easy to set up and maintain, and easy to carry. The connection of the external modem is also very convenient, and the connection of the phone and line is the same as that of the built-in modem. However, an external modem must use a serial cable to connect one of the serial ports of the computer to the serial port of the modem, and this serial cable is usually shipped with the external modem.

An important performance parameter of the modem is the transmission rate, which is currently available in both 56k modems on the market, and 56k modems have become the mainstream products in the market. However, due to the limitation of domestic communication lines, as well as the fact that there are too many users and too few international exports, it is difficult to achieve the above rates in normal use, so if the transmission rate is only a few kilobytes per second or even lower when you use it, you don't need to wonder if there is something wrong with your computer or modem.

The main function of the modem is to convert the analog signal of ** into a digital signal for the computer, and its bandwidth is: 2m, 4m, 6m

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1. It is mainly used for dial-up Internet access, and at present, many families are dial-up Internet access, and the modem we call here is used. It is a must-have hardware device for dial-up access to the Internet. Usually the computer uses "digital signals" internally, and the signals transmitted through ** lines are "analog signals".

2. The function of the modem is that when the computer sends information, the digital signal used inside the computer is converted into an analog signal that can be transmitted by the first line, and the socks are sent out through the first line; When receiving information, the analog signal transmitted from the ** line is converted into a digital signal and transmitted to the computer for its reception and processing.

3. Professionally speaking, the general term for modulator and demodulator together, so that digital data can be transmitted on the analog signal transmission line conversion interface. In the computer, the modem generally refers to the mod** from the computer Pepsi EM, which everyone likes to call the "cat" modem.

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Classification of modems:

External modem

The external modem is placed outside the chassis and connected to the host computer through the serial communication port. The modem is handy, easy to install, and the flashing indicator light makes it easy to monitor the operating condition of the modem. However, the external modem requires the use of additional power supplies and cables.

Built-in modem

The built-in modem needs to disassemble the chassis when installing in Anzhenmin, and the terminal and COM port need to be set, which is cumbersome to install. This modem takes up the expansion slot on the motherboard, but does not require additional power supplies and cables, and is cheaper than an external modem.

A modem, short for modulator and demodulator, is a type of computer hardware.

The modem is composed of two parts, the modulator and the demodulator, wherein the modulator modulates the data information into a signal suitable for transmission channel transmission, and the demodulator demodulates and restores the received signal into data information, and the modem belongs to the data circuit equipment DCE in the data communication equipment.

Wireless modem is designed for the wireless transmission of digital signals of data communication on a simulated channel with limited bandwidth, and it is generally composed of baseband processing, modulation and demodulation, signal amplification and filtering, equalization and other parts, "wireless modem" is also known as wireless modem.

The use of modem can also convert audio signals into higher frequency signals and higher frequency signals into audio signals, so another purpose of modulation is to facilitate line reuse, so as to improve line utilization.

The role of a modulator

The data signal emitted by the signal source can be successfully converted into an analog signal suitable for analog signal transmission, and at one end of the data, it will complete the conversion in the opposite direction of the signal source, and can also deal with the noise and distortion waveform.

When the number of Piga gods is transmitted, the information will continue to be synchronized at the receiving end, it will extract the synchronous information sent and have a genlock, and then use the generated carrier in phase with the source for sampling and the timing of the signal generation, so as to ensure the synchronization of the letter and the source.

The hard disk can also take advantage of the orthogonality of the seat number to realize channel multiplexing by using various coding and modulation methods. At the same time, it can also compensate for the interference damage of harmful factors to the signal.