What is a Modem
A Modem (also called Modulator-Demodulator) is an electronic device which is used to link a user’s home network to the Internet. This link is established with the help of Internet Service Provider (ISP). It actually acts as a bridge between computer and telephone lines. It converts signals and is also known as a device that allows communication. Modems convert analog data into digital data and also perform the reverse so it can be transmitted. Analog Data is transmitted over phone lines and Digital data is read by the computers. This means that the modem translates computer data into the language used by telephones and then reverses the process to translate the responding data back into computer language. The whole process is performed because telephone lines only accept analog signals and computers only accept digital signals.
The speed of Modem’s transmission is very slow as it uses telephone lines while a broadband connection or other form of internet connections can provide the user with greater speeds than that of Modem. Phone companies and television companies also have started to use DSL connections and cable connections for sending the data. Depending upon the user’s needs, he or she can choose that which modem he or she has to go for.
There are different types of Modems. These are classified on the basis of the capacity to carry data:
These are built-in modems or PC card modems. A PCI slot or an ISA slot is provided depending on the availability of interface with the motherboard. Internal modems are used with a Dial-up Internet connection or the RJ-11 connection and the user can send or receive data.
The external modem being a small box uses other kind of interfaces to connect to the computer. It can be a serial modem (installed at the back of a computer) or an USB modem that uses a USB port.
A cable Modem uses coaxial cable television lines to provide greater bandwidth than a Dial-up Modem. It provides fast access to the Web. The transmission rate fluctuates with the number of users due to the sharing of the bandwidth.
DSL (Digital Subscriber Line)Modem is exclusively used for connections from a telephone switching office to the user. It is divided into two categories: ADSL (Asymmetric Digital Subscriber Line) and SDSL (Symmetric Digital Subscriber Line).