cable modem

cable modem

Modem used to convert analog data signals to digital form and vise versa, for transmission or receipt over cable television lines, especially for connecting to the Internet. A cable modem modulates and demodulates signals like a telephone modem, but is a much more complex device. Data can be transferred over cable lines much more quickly than over traditional phone lines. Transmission rates are typically around 1.5 megabits per second. Faster transmission is actually possible, but speed is usually restricted by the cable company's (typically slower) connection to the Internet. Cable Internet access is regarded as a replacement for slower dial-up and ISDN services, and is competitive with other broadband modes of delivery (e.g., DSL connections). See also broadband technology.

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cable modem

A device used to connect a single computer or a network to a cable company's service for Internet access. The same physical cable coming into the house or office also provides TV and voice (VoIP) service.

Compared to analog dial-up, cable Internet dramatically increases the bandwidth between the user's computer and the Internet (see broadband). In order to prevent users with lower-cost cable access from hosting high-traffic Web servers, the upload speed is approximately five times slower than the download speed. Cable operators also routinely change IP addresses assigned to users to prevent Web hosting (see DDNS).

Connect Via Ethernet or USB
Cable modems typically connect to the computer or network router via an Ethernet port; however, some cable modems have a USB port for hookup to the computer but not the network.

Cable Internet is a shared service, and the individual user's speed will vary depending on how many customers are sending or receiving data on that cable segment at the same time. For example, when kids come home from school in the afternoon, many neighborhood users experience slower speeds. See DOCSIS, cable Internet, Internet appliance and MSN TV.

A Cable Modem System

Internet packets are combined with standard TV programming in a cable modem system. The cable modem termination system (CMTS) is responsible for packet to RF conversion, routing, bridging, filtering and traffic shaping (see CMTS).

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cable modem [¦kā·bəl ¦mō‚dem]

(electricity)

A device that converts the signals used in a computer to signals that can be transmitted over cable television networks, and vice versa.

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(communications, hardware)

cable modem - A type of modem that allows people to access the Internet via their cable television service. A cable modem can transfer data at 500 kbps or higher, compared with 28.8 kbps for common telephone line modems, but the actual transfer rates may be lower depending on the number of other simultaneous users on the same cable. Industry pundits often point out that the cable system still does not have the bandwidth or service level in many areas to make this feasible. For example, it has to be capable of two-way communication. See also: DOCSIS.