2.45 spectrum. (a) Description, for a function of time, of the resolution of a signal into components, each of different frequency and (usually) different amplitude and phase. (b) “Spectrum” is also used to signify a continuous range of components, usually wide in extent, within which waves have some specified common characteristic; e.g., “audio frequency spectrum.”
Annotation 1 The term “spectrum” is also applied to functions of variables other than time, such as distance.
Annotation 2 As defined here, “spectrum” defines a Fourier analysis of a signal or noise of a waveform. Basis functions other than sinusoids can be used, providing spectra other than Fourier.« Back to Standards Terminolgy Index