Modem: Encyclopedia II - Modem - Broadband

Modem - Broadband

ADSL modems, a more recent development, are not limited to the telephone's "voiceband" audio frequencies. Some ADSL modems use coded orthogonal frequency division modulation.

Cable modems use a range of frequencies originally intended to carry RF television channels. Multiple cable modems attached to a single cable can use the same frequency band, using a low-level media access protocol to allow them to work together within the same channel. Typically, 'up' and 'down' signals are kept separate using frequency division multiplexing.

New types of broadband modems are beginning to appear, such as doubleway satellite and powerline modems.

Broadband modems should still be classed as modems, since they do utilise analog/digital conversion. They are more advanced devices that traditional telephone modems as they are capable of modulating/demodulating hundreds of channels simultaneously.

Many broadband "modems" include the functions of a router and other features such as DHCP, NAT and firewall features.

When broadband technology was introduced, networking and routers were not very familiar to most people. However, many people knew what a modem was as most internet access was through dialup. Due to this familiarity, companies started selling broadband adapters using the familiar term "modem".

Adapted from the Wikipedia article "Broadband", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki