Q.What do you mean by a modem? Why is it used?
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Start your 14-day free trial to unlock the full solution →A modem is a device that converts digital signals to analog (modulation) and analog back to digital (demodulation), enabling computers to communicate over telephone lines and cable networks.
The name "modem" is a portmanteau of modulator-demodulator, which describes exactly what the device does. Computers work with digital data—discrete 0s and 1s—but traditional communication channels like telephone lines were designed to carry analog signals (continuous waves). A modem bridges this gap by performing two complementary tasks:
Modulation converts the digital data from your computer into analog signals that can travel over the transmission medium. Think of it as translating binary pulses into sound waves or radio frequencies.
Demodulation does the reverse at the receiving end: it decodes the incoming analog signal back into digital data your computer can understand.
Why is a modem used?
The fundamental reason is compatibility between digital devices and analog transmission media. Early internet connections relied on the existing telephone infrastructure, which was built for voice (analog). Without a modem, your computer's digital signals would be incompatible with these lines.
Even today, though many networks are digital end-to-end, modems remain essential:
- DSL modems convert digital data to high-frequency signals that share telephone lines with voice calls.
- Cable modems modulate data onto the same coaxial cables that carry television signals.
- Fiber modems (often called ONTs—Optical Network Terminals) convert between electrical and optical signals. …
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