PDF of this tutorialThe term modem is actually an acronym which stands for MOdulation/DEModulation. A modem enables two computers to communicate by using the public switched telephone network. This network can only carry sounds so modems need to translate the computer's digital information into a series of high-pitched sounds which can be transported over the phone lines. When the sounds arrive at their destination, they are demodulated—turned back into digital information for the receiving computer (see Figure 1).
Figure 1.
All modems use some form of compression and error correction. Compression algorithms enable throughput to be enhanced two to four times over normal transmission. Error correction examines incoming data for integrity and requests retransmission of a packet when it detects a problem.
