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An Improved Modem (1958)

Though modems existed for teletype since the 1940s, these transmitted at speeds of about 150 bpi. To meet demands of the U.S. military, in 1958 researchers at Bell Labs developed an improved modem (modulator-demodulator), using amplitude magnification to provide a way to convert digital signals to analog signals and back for transmission at speeds up to 1600 bpi over analog telephone lines.