Editing Group delay and phase delay (section)

=== Frequency components of a signal ===
{{Main|Sine wave|Fourier analysis|Linear time-invariant system}}
[[Fourier analysis]] reveals how [[signals]] in time can alternatively be expressed as the sum of [[sinusoidal]] [[frequency component]]s, each based on the trigonometric function <math>\sin(x)</math> with a fixed amplitude and phase and no beginning and no end.

[[Linear time-invariant system]]s process each sinusoidal component independently; the property of [[linearity]] means they satisfy the [[superposition principle]].