A stencil generator for automatically constructing a stencil representative of signals having similar characteristics includes a boundary extractor and a component generator. The boundary extractor is operable to (i) receive a frequency spectrum of a signal, and (ii) obtain from the received frequency spectrum a plurality of characteristic frequency boundaries for the signal. The component generator is coupled to the boundary extractor and is operable to (i) receive the frequency spectrum, (ii) receive the plurality of characteristic frequency boundaries from the boundary extractor, and (iii) define a plurality of stencil components based upon the plurality of characteristic frequency boundaries and the frequency spectrum.