Bandwidth (signal processing)

Bandwidth is typically measured in hertz, and may sometimes refer to passband bandwidth, sometimes to baseband bandwidth, depending on context. Passband bandwidth is the difference between the upper and lower cutoff frequencies of, for example, an electronic filter, a communication channel, or a signal spectrum. In case of a lowpass filter or baseband signal, the bandwidth is equal to its upper cutoff frequency. The term baseband bandwidth refers to the upper cutoff frequency. Bandwidth in hertz is a central concept in many fields, including electronics, information theory, radio communications, signal processing, and spectroscopy.

In computer networking and other digital fields, the term bandwidth often refers to a data rate measured in bits per second, for example network throughput. The reason is that according to Hartley's law, the digital data rate limit (or channel capacity) of a physical communication link is related to its bandwidth in hertz, sometimes denoted frequency bandwidth, analog bandwidth or radio bandwidth. For bandwidth as a computing term, less ambiguous terms are bit rate, throughput, maximum throughput, goodput or channel capacity.