The Carlisle Mosquito Online

Friday, August 31, 2001


What is broadband?

The computer industry has adopted some terms like broadband and bandwidth from radio. Historically, the "band" in these words actually refers to the spectrum of radio waves; in radio broadcasting broadband means "operating at, responsive to, or comprising a wide band of frequencies," according to Merriam Webster. If you have a license to broadcast in an 8MHz range, your bandwidth is twice as large as that of someone who can only broadcast in a 4MHz range.

Computer network communication doesn't usually use radio waves for transmitting data, so these terms are technically meaningless. But we stole them anyway because the concepts still apply; we use bandwidth to mean how fast you can transmit data on a network, and broadband to mean pretty much any high-speed data link.

Different sources use different speed thresholds to define broadband. The FCC says that broadband is any kind of link that transmits data at 200Kbps or faster. Some other sources say that anything faster than 14.4Kbps is broadband, which is a little more realistic. In any case, there's no formal definition of how fast something has to be in order to constitute broadband.

What can be confusing to the uninitiated is that the term broadband may be used to refer to any of the several modes of high speed data transmission, and more specifically, to the use of cable for data as well as television channels.

Among the principal broadband modes for data transmission are: (1) cable modem, also referred to as broadband, transmitting both television and data through wires provided and maintained by a cable company; (2) DSL (digital subscriber line) moving data through telephone lines owned and maintained by a telephone company; and (3) various wireless technologies requiring a satellite dish or antenna, including direct satellite transmission to the home. Residents' experience with wireless service is reportedly somewhat uneven in Carlisle, especially in wooded areas and poor weather.

Thus, most hopes for high-speed Internet access have centered on two possible alternatives: that Verizon will upgrade the central office near Town Hall to offer DSL (a recent announcement of 2002 as a starting date was greeted with skepticism by many) or that AT&T will upgrade the cable system. (See story starting on page 1.)

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