Another term used when referring to transmission speed is bandwidth. Although this term
is often used to refer to the maximum data transmission capacity, this is accurate only
when referring to purely digital systems. Strictly speaking, in analog systems, bandwidth
is defined as the range of frequencies that can be transmitted by a particular system or
medium. In simple terms, bandwidth is the difference between the higher frequency and
the lower frequency. Suppose a transmission for a human voice could be sent between
300 Hz and 3,400 Hz. The difference between the two frequencies (3,400 Hz minus
300 Hz) is 3,100 Hz, which happens to be the bandwidth of a human voice that is transmitted
during a telephone conversation.