(1) High-speed transmission. The term commonly refers to Internet access via cable and DSL, which is as much as 1,000 times faster than analog dial-up. The term has always referred to a higher-speed connection, but the speed threshold varies with the times. Widely employed in companies, the 1.5 Mbps T1 line was often considered the starting point for broadband speeds, while the FCC defined broadband as a minimum upload speed of 200 Kbps.
The T1 line is no longer the coveted connection for Web surfing. Home users with cable modems experience speeds many times that of T1 (see cable modem). For example, Comcast offers a variety of Internet access plans from economy service at 1 Mbps download to as high as 50 Mbps. See broadband router, wireless broadband, T1, cable modem and DSL.
(2) Transmitting data by modulating a carrier wave in order to differentiate it from other signals in the air or in a single line. For example, frequency division multiplexing (FDM) is used to carry hundreds of channels of analog and digital TV in a single coaxial cable. In this context, broadband is used in contrast with "baseband," which is data that has not been modulated or multiplexed (see baseband and TDM). In most cases, the term "broadband" is used for high-speed transmission as in definition #1 above.
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