EECS20N: Signals and Systems


Linear time invariant systems have the property that if the input is described as a sum of sinusoids, then the output is a sum of sinusoids of the same frequency. Each sinusoidal component might be scaled differently, and each may be subjected to a phase change, but the output will not contain any sinusoidal components that are not also present in the input.

LTI systems are often used to remove sinusoidal components from a signal. For this reason, an LTI system is often called a filter.