Electronic device that converts digital data into analog (modulated-wave) signals suitable for transmission over analog telecommunications circuits (e.g., traditional phone lines) and demodulates received analog signals to recover the digital data transmitted. The modulator/demodulator thus makes it possible for existing communications channels to support a variety of digital communications, including e-mail, Internet access, and fax transmissions. An ordinary modem, operating over traditional phone lines, has a data transmission speed limit of about 56 kilobits per second. ISDN lines allow communications at over twice that rate, and cable modems and DSL lines have transmission rates of over a million bits per second.
This entry comes from Encyclopædia Britannica Concise.
For the full entry on modem, visit Britannica.com.
Seen & Heard
What made you look up modem? Please tell us what you were reading, watching or discussing that led you here.