 - The kilohertz, abbreviated kHz or KHz*, is a unit
of alternating current (AC) or electromagnetic (EM) wave
frequency equal to one thousand hertz (1,000 Hz). The unit
is also used in measurements or statements of signal bandwidth.
An AC signal having a frequency of 1 kHz is
within the range of human hearing. If a signal at this frequency
is input to a headset or loudspeaker, the resulting tone has a
pitch that falls into the so-called "audio midrange."
An EM signal at a frequency of 1 kHz has a wavelength of 300
kilometers, or about 190 miles. The standard amplitude-modulation
(AM) broadcast band extends from 535 kHz to 1,605 kHz. Some EM
transmissions are made at millions of kHz.
The kilohertz is a relatively small unit of
frequency; more common units are the MHz, equal to
1,000,000 Hz or 1,000 kHz, and the GHz, equal to
1,000,000,000 Hz or 1,000,000 kHz.
The kilohertz is often used to specify bandwidth
for digital as well
as analog signals. The
bandwidth of a digital signal, in kilohertz, is related to the
data speed in bits per second. In general, the greater the data speed, the larger the
bandwidth. Data speed is not, however, the same thing as
bandwidth. A modem operating at a speed of 28,800 bps has, in a
certain sense, a nominal frequency of 28.8 kHz. But the bandwidth
is generally much smaller, because it depends on variations in
the individual data characters, not on the number of data bits
per unit time.
* The engineer's society, IEEE, and most other sources prefer "kHz" to "KHz." This apparently makes it less likely that users will confuse "kilo" (decimal 1,000) with the computer "K" (1,024).
| LAST UPDATED: |
29 Jul 2001
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