a) In computer networks,
bandwidth is often used as a synonym for data transfer rate - the amount of
data that can be carried from one point to another in a given time period
(usually a second). This kind of bandwidth is usually expressed in bits (of
data) per second (bps). Occasionally, it's expressed as bytes per second (Bps).
A modem that works at 57,600 bps hastwice the bandwidth of a modem that works
at 28,800 bps. In general, a link with a high bandwidth is one that may be able
to carry enough information to sustain the succession of images in a video
presentation.
It
should be remembered that a real communications path usually consists of a
succession of links, each with its own bandwidth. If one of these is much
slower than the rest, it is said to be a bandwidth bottleneck.
b) In electronic
communication, bandwidth is the width of the range (or band) of frequencies
that an electronic signal uses on a given transmission medium. In this usage,
bandwidth is expressed in terms of the difference between the highest-frequency
signal component and the lowest-frequency signal component. Since the frequency
of a signal is measured in hertz (the number of cycles of change per second), a
given bandwidth is the difference in hertz between the highest frequency the
signal uses and the lowest frequency it uses. A typical voice signal has a
bandwidth of approximately three kilohertz (3 kHz); an analog television (TV)
broadcast video signal has a bandwidth of six megahertz (6 MHz) -- some 2,000
times as wide as the voice signal.
