what is a modem
FREE IEEE PAPERS
modems enable computers to transmit data over telephone lines or via wireless signals. Modem is a contraction of the words modulator-demodulator. Since computer information is digital data and information transmitted over the telephone lines is transmitted in analog waves, a modem converts between these two forms. The speed at which a modem transmits data is measured in units called bits per second or bps. A cable modem IC uses a range of frequencies. When attached to a single cable, cable modems can use the same frequency band, using a low-level media access protocol to allow them to work together with in the same channel. There are many different types of IC modems. Examples include a wireless modem and a wireline modem. A wireless modem converts digital data into radio signals and back. A wireless modem transmits information that is modulated onto a carrier frequency to allow many simultaneous wireless communications links to work simultaneously on different frequencies. A wireline modem delivers two or four wire operations and supports dial up, leased line, or dedicated circuits. This is ideally suited for remote network management and “lights out” operations, applications demanding reliability. Other types of IC modems are commonly available.