Modem - Broadband

Broadband

ADSL (asymmetric digital subscriber line) modems, a more recent development, are not limited to the telephone's voiceband audio frequencies. Some ADSL modems use coded orthogonal frequency division modulation (DMT, for Discrete MultiTone; also called COFDM, for digital TV in much of the world).

DSL modems utilize a property that standard twisted-pair telephone cable can be used for short distances to carry much higher frequency signals than what the cable is actually rated to handle. This is also why DSL modems have a distance limitation. Standard voice and slower 56 kilobit modem communications are possible over many kilometers of cable, but the higher frequencies used by DSL are attenuated and DSL's maximum performance gradually declines as the cable length increases.

Cable modems use a range of frequencies originally intended to carry RF television channels, and can coexist on the same single cable alongside standard RF channel signals. 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, uplink and downlink signals are kept separate using frequency division multiple access.

For a single-cable distribution system, the return signals from customers require special bidirectional amplifiers or reverse path amplifiers that can send specific customer frequency bands upstream to the cable plant amongst the other downstream frequency bands.

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

Broadband modems should still be classified as modems, since they use complex waveforms to carry digital data. They are more advanced devices than traditional dial-up modems as they are capable of modulating/demodulating hundreds of channels simultaneously.

Many broadband modems include the functions of a router, such as Ethernet and WiFi, and other features such as DHCP, NAT and firewalls.

When broadband technology was introduced, networking and routers were unfamiliar to consumers. However, many people knew what a modem was because Internet access was still commonly done through dial-up. Due to this familiarity, companies started selling broadband modems using the familiar term "modem", rather than vaguer ones such as "adapter," "transceiver," or "bridge."

Read more about this topic:  Modem

Other articles related to "broadband":

Broadband - Internet Access
... The standards group CCITT defined "broadband service" in 1988 as requiring transmission channels capable of supporting bit rates greater than the primary ... Broadband became a marketing buzzword for telephone and cable companies to sell their more expensive higher data rate products, especially for Internet access ... In the US National Broadband Plan of 2009 it was defined as "Internet access that is always on and faster than the traditional dial-up access" ...
Statistics About The Economy Of Bulgaria - Miscellaneous Data
... telephone - 62% (2009) mobile telephone - 78% (2009) Broadband penetration rate fixed broadband- 13.0% (2010) mobile broadband- 1.3% (2010) Individuals using computer and internet computer - 47% (2009) internet ...
SES Broadband - Maritime Broadband
... SES Broadband for Maritime was launched in September 2009 to provide satellite internet access for vessels at sea and on inland waterways in the European region ... The SES Broadband for Maritime service uses the same satellite modem, as the land-based solution, but the terminal deployed is a professional 85 cm (33 in) in-motion marine dish with automatic tracking ... The service provider for maritime users across all Europe supplies broadband and the hardware for a fixed monthly subscription ...
List Of Internet Service Providers In India - Privately Owned, Regional
... Ortel Cable - Broadband over Cable, Odisha Dreamtel - Wireless Turbo Broadband,Jalandhar 9855551177 - Dreamtel offers a wide range of Wi-Fi internet broadband plans suiting the need of the ... UK, Canada 9716629575 - Regional ISP, Noida, Greater Noida, Ghaziabad Flymax Broadband Internet Services- Cuddalore Old Town,Tamil nadu ... contact number-91-9486289294 Asianet Data Line - Broadband over Cable, Kerala excel - Broadband over Cable, andhrapradesh Kappa Internet Services - Broadband over Wireless, Rajasthan Beam Telecom - FTTB ...
SES Broadband
... SES Broadband (previously ASTRA2Connect) is a two-way satellite broadband Internet service available across Europe, which launched in March 2007, and uses the Astra series of geostationary satellites ... SES Broadband is owned and operated by SES Broadband Services, a subsidiary of SES, based in Betzdorf, Luxembourg ... SES Broadband provides high-speed Internet access (at up to 10Mbit/s) at a flat rate cost to end users, along with VoIP, IPTV, and content-on-demand facilities, without any requirement for a landline, cable or ...