Modems

Modem is a network device that enables a computer to transfer data from telephone lines to computers and computers to telephone lines.
The word modem is derived from modulator and demodulator.
Modem performs modulation and demodulation.

1. Modems

2. Modems Modem is a network device that enables a computer to transfer data from telephone lines to computers and computers to telephone lines. The word modem is derived from modulator and demodulator. Modem performs modulation and demodulation.

3. Modem The process of converting digital information into analog signals is called modulation. The process of converting analog signals into digital signals is known as demodulation.

4. Modem – MOdulator - DEModulator Modems are devices used by computers to communicate over long distances. A modem is typically used to send digital data over a phone line. The sending modem modulates the data into a signal that is compatible with the phone line, and the receiving modem demodulates the signal back into digital data.

5. Features of modem Modems differ from each other depending upon their characteristics. Different modems may support different types of communication such as Data, Fax or voice. Different modems have different data transmission speed and are designed to work with different protocols. Transmission speed. Voice or Data communication. Auto answering. Fax capability. Most common features of a modem are:

6. Working of modem Modulation and Demodulation

7. Types of modems External Modems Internal Modems

8. Types of modems An internal modem is a Add – on – card that we can plug into expansion slot of the computer. These modems use the power supply from the computer. Lightening effects. An external modem can be connect to the computer through RS – 232 cable to the serial port. External modems have their own power cords.

9. Internal Modem connected to the Computer RJ11

10. How to Connect external Dial Up Modem

11. Types of external modems X2 Modem. V90 Modem. ISDN Modem. DSL Modem. Cable Modem.

12. X2 modem The United States Robotics developed a technology called X2 for transmitting data at the speed of 56 kbps over old phone lines. X2 technology transmits data at the speed of 56 kbps.

13. V90 Modem V90 is a modulation standard. V90 technology helps to increase the data transfer speed from the internet to the computer. Now a days X2 modems use V90 modulation standard.

14. ISDN Modem Integrated Services Digital Network modem. This is a set of international communication standard for transmitting digital data over a telephone line. It transmits the data at the speed of 64 kbps. It enables to send data, voice and video over digital and analog phone lines.

15. DSL Modem Digital Subscriber Line modem. It is high – speed connection that allows the phone wires to transmit modulated digital data at high speed. DSL can carry both voice and data at the same time. DSL modems are also known as DSL transceiver. USB port or LAN port.

16. Cable Modem A cable modem is a device that enables to connect a computer to the cable TV line. It’s data transfer rate is very high than normal modems, ISDN and DSL modems. Two kinds of cable modems are there. External cable modems and Internal cable modems.

17. External modem controls Power LED. Speed Indicator. Mode Indicator. Auto answer. Dial LED. Send LED. Receive LED. Error Indicator.

18. Modes of modem Full duplex. In full duplex data can be send and receive at a time. No data loss. Half duplex. In half duplex either we can send or receive data at a particular time. Data loss may occurs.

19. Modem standards standard Description V32 bis Supports full duplex transmission at a speed of up to 14000 bps. V34 Supports full duplex transmission at a speed of up to 28800 bps. V42 Regulates error – detection for high speed modems. This standard enables modems to work with both digital and analog phone lines. V42 bis Used for data compression that enables to transmit data at a speed of up to 34000 bps. X2 Supports data transmission at a speed of up to 56 kbps. V90 Integrate both k56Flex and X2 standards into one. V92 Along with V90 standard features and modem hold, quick connect.

20. Modem protocols protocol Description Automatic Repeat Request (ARQ) Enables the modem to automatically request to retransmit any corrupted data. It helps to control error in data transmission. Link Access Protocol (LAP) Same as ARQ protocol, along with that it uses cyclic redundancy checking for corrupted data. Microcom Network Protocol Used to control error in data transmission and perform data compression before transmission. MNP offers various levels. MNP level 4  Error correction. MNP level 5  Data compression. MNP level 6  Error correction and data compression. k56Flex It is an interoperable high speed modem protocol.

21. Installation of modem. Installation of modem is very simple. Click on Start  Control Panel Phone and Modem and then follow on screen options. If it is internal modem place the modem in PCI slot and then install the drivers.

22. Let, go to use modem….!