Modem

Uncommon card · No. 105223

A modulator-demodulator, commonly referred to as a modem, is a computer hardware device that converts data from a digital format into a format suitable for an analog transmission medium such as telephone or radio. A modem transmits data by modulating one or more carrier wave signals to encode digital information, while the receiver demodulates the signal to recreate the original digital information. The goal is to produce a signal that can be transmitted easily and decoded reliably. Modems can be used with almost any means of transmitting analog signals, from LEDs to radio. Early modems were devices that used audible sounds suitable for transmission over traditional telephone systems and leased lines. These generally provided Asynchronous communications at 110 or 300 bits per second (bit/s), and the connection between devices was normally manual, using an attached analogue telephone handset. By the 1970s, higher speeds of 1,200 and 2,400 bit/s for asynchronous dial connections, 4,800 bit/s...

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