5 Networks
The ordinary telephone system handles voice signals in an analog fashion. Analog signals mimic the original information varying in strength like the air pressure waves of the voice. Analog signals suffer from serious disadvantages for high speed transmission. Digital signals overcome the limitations of analog transmission. Digital signals represent information in discrete values that can be transmitted as a series of coded pulses. Modems (modulator/demodulators) adapt the analog telephone system to carry digital information. In the modern world transmission media such as digital subscriber lines (DSL), modems for cable television systems, fiber optic cable and extremely high frequency radio (wireless) methods have been developed to provide high speed pathways for digital signals. These technologies now make it possible to connect computers in local area networks (LAN) within one or more buildings or wide area networks (WAN) over distances of many miles.