The functions are: 1. Convert the data signal sent by the source into an analog signal suitable for analog channel transmission; 2. At the receiving end, it will synchronously extract and phase-lock the synchronization information sent for Generate carriers of the same frequency and phase as the signal source for the signal sink to generate timing and sampling to ensure synchronization between the signal source and the signal sink; 3. Compensate for the interference damage to the signal caused by harmful factors; 4. Utilize the orthogonality of the seat numbers to use multiple A coding and modulation method realizes channel multiplexing; 5. Direct connection; 6. Automatic redialing; 7. Soft phone book, allowing users to control calls through software; 8. Baud conversion.
The operating environment of this tutorial: Windows 7 system, Dell G3 computer.
Modem (English name Modem), commonly known as "cat", is a kind of computer hardware.
It translates the computer's digital signals into pulse signals that can be transmitted along ordinary telephone lines, and these pulse 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 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. Therefore, when two computers want to transmit data through a telephone line, a device is needed to perform digital-to-analog conversion.
Function of modem
1. Signal conversion: Convert the data signal sent by the source into an analog signal suitable for analog channel transmission. At the sink end, it will be completed Conversion inverse of the source and processing of waveforms that also contain distortion and noise.
2. Synchronous transmission: There is synchronization information in the transmitted data stream. At the receiving end, it will synchronously extract and phase-lock the synchronization information sent to generate a carrier with the same frequency and phase as the source. , used for information sink generation timing and sampling to ensure that the information source and information sink are synchronized.
3. Compensation for interference: Compensation for interference and damage to signals caused by harmful factors.
4. Multiplexing: Taking advantage of the orthogonality of seat numbers, a variety of coding and modulation methods are used to achieve channel multiplexing.
5. Direct connection: For example, the user can directly connect the modem's telephone line without acoustic coupling facilities; the user can send sequence information to the modem through the communication link and convert it into a response. The user can also start the operation through the PC Keyboard software accesses the phone number stored on disk and instructs the modem to dial the number and establish carrier signal contact with the host system.
6. Automatic redialing: You can redial the last number called to the modem, which makes it easy to make up for the number that was not dialed because the line was busy or the carrier signal was not detected.
7. Soft phone book: Some modems allow users to control calls through software
8. Baud conversion: The modem can detect the input and output baud rate and convert it to this baud rate.
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