Filtering is a way to process an input signal so that the output signal has interesting features enhanced or unwanted features reduced.
Filtering is a way to process an input signal so that the output signal has interesting features enhanced or unwanted features reduced.
Filtering can be linear or non-linear.
Linear filtering satisfies scaling $$ {\cal F}[ \alpha x(t) ] = \alpha {\cal F}[ x(t) ] $$ and superposition $$ {\cal F}[ x(t) + y(t) ] = {\cal F}[ x(t) ] + {\cal F}[ y(t) ]. $$
