'Modem' is a word that was intelligently carved out of the words 'modulator' and 'demodulator'. Technically speaking, a modem is a device that modulates an analog carrier signal to encode digital information and demodulates it to decode information. It is commonly used for Internet access.
How does a Modem Work?
When a modem starts making a connection, the sounds from the modem that are digital are being modulated into audible signals. Modems use different pitched tones to represent 1s and 0s. The sounds produced can be transmitted over telephone lines. When the computer you are connecting to, receives these signals, they are demodulated back to digital signals.
Modems may implement checksums which allow the computers communicating over a network to check data integrity. They can resend missing data segments if they find a loss of integrity in the data being transmitted over the network.
Some modems also employ compression strategies to increase their capacity of data transmission. Sometimes, modems have to use their buffers to hold data, while it is being compressed before transmission. At times, the computer is instructed to pause data transmission.
Different Types of Modems
Cable modems and ADSL modems are examples of faster modems in use today. Cable modems use the cable TV infrastructure to provide users with an access to digital signals. It harnesses the high bandwidth of cable television networks.
ADSL modems connect computers or routers to a DSL phone line. Some DSL modems allow the sharing of ADSL service between a group of computers.
Satellite modems use communication satellites as relays to bring about data transfers. These modems convert bit streams into radio signals. They provide Internet users with a satellite Internet access.
Wireless modems have revolutionized Internet access as they can offer Internet connectivity with the use of the very ubiquitous mobile phones. Mobile phones serve as gateways between the service provider and computers.