Modem

A modem (modulator-demodulator) is a network hardware device that modulates one or more carrier wave signals to encode digital information for transmission and demodulates signals to decode the transmitted information. 

Modem converts information from digital mode to analog mode at the transmitting end and demodulator converts the same from analog to digital at receiving end through telephone lines.

Types of Modem

Internal computer modems

An internal modem is a device installed inside a desktop or laptop computer, allowing the computer to communicate over a network with other connected computers.

 

 External modem

External modems are the simplest type of the modem to install this kind of modem you don’t open the computer. The telephone line plugs into a socket on the rear panel of the modem.

Cable modem

The cable modem uses a coaxial cable television lines to provide a greater bandwidth than the dial-up computer modem. An extremely fast access to the Web is providing by the cable modem with downstream transmission up to 38 Mbits/s and an upstream transmission up to 1 Mbits/s.

DSL modem

DSL (Digital Subscriber Line) modem is exclusively used for connections from a telephone switching office to the user.  DSL modem is a device used to connect a single computer or router to a DSL phone line, in order to use an ADSL service.