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A modem (a portmanteau constructed from modulate and demodulate) is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data. Modems can be used over any means of transmitting analog signals, from driven diodes to radio. Experiments have even been performed in the use of modems over the medium of two cans connected by a string.

The most familiar example of a modem turns the digital '1s and 0s' of a personal computer into sounds that can be transmitted over the telephone lines of Plain Old Telephone System (POTS), and once received on the other side, converts those sounds back into 1s and 0s. Modems are generally classified by the amount of data they can send in a given time, normally measured in bits per second, or "bps".

Far more exotic modems are used by internet users every day, notably cable modems and ADSL modems. In telecommunications, "radio modems" transmit repeating frames of data at very high data rates over microwave radio links. Some microwave modems transmit more than a hundred million bits per second. Optical modems transmit data over optic fibers. Most intercontinental data links now use optic modems transmitting over undersea optical fibers. Optical modems routinely have data rates in excess of a billion (1x109) bits per second.

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Data Communications FAQ (Windows Version) - FAQ for SLIP or PPP and wanting a high speed connection.

High-speed Modems - Describes requirements for high-speed modem connections, and what to look for when buying a new modem.
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Modem Driver.com - Many modem driver software links, a library of hard to find files and email help.

Modem Speed Test Page - Provides tests to measure how long it takes to load a test page from its server, and display it on the host browser.

Modem-help - Technical information for dial-up, cable and ISDN modems.
Meta Description: [ This is the Home page of Modem-Help, a site dedicated to providing assistance to modem users. `Modem` is used in the generic sense - links & info are provided for ISDN, Cable & Broadband (DSL & ADSL) digital-modems as well as V.92, V.90, V34 & slower analog-modems. The Site speciality is modem id... ]

ModemHelp.Net - Features DUN error fixes, line noise information, init string database, forums, and articles.

ModemHelp.Org - Modem resource site, providing links and documentation for modems.
Meta Description: [ This site is a free resource site for users, ranging from beginners to advanced users. This site contains links to manufacturer support, driver sites, a discusson list and a massive list of init strings. ]

Modems.com - Information on modem and related technologies from Zoom Telephonics.

Modemsite.com - A reliable source of 56k modem information, troubleshooting, and modem driver downloads.
Meta Description: [ Modemsite.com (formerly 56k=v.Unreliable): Internet Connectivity, Modem Drivers, Troubleshooting Connection Problems. This is the Top page of the site. ]

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