Bandwidth : Bandwidth of a communications channel is a measure of the range of frequencies over which the carrier signal is allowed to vary. Generally a communications channel is defined by its lowest and highest frequency, and channel bandwidth is computed as the difference between the two as measured in Hertz, kHz or MHz. Since bandwidth of a channel is directly proportional to the amount of data that can be transmitted over it per unit time, channel bandwidth is sometimes measured as a data rate rather a frequency difference. Technical term for the capacity of a transmission channel. Because capacity, or even maximum speed, is generally dependent on the frequency range available, the ‘bandwidth’ (i.e., the width of a frequency band) usually has the same meaning as the maximum transmission speed available to a subscriber.