Amplification and distortion of a periodic rectangular driving signal by a noisy bistable system.

The response of a symmetric bistable system driven by a time periodic rectangular input signal and subject to a white noise is studied. The analysis shows that the stochastic resonant enhancement of a weak amplitude signal implies a distortion of the input shape for intermediate frequencies, due to the dispersivity of the response. On the other hand, the shape can be maintained and the amplitude greatly amplified for very low input frequencies and some values of the noise strengths. These results are corroborated by numerical solutions of the Fokker-Planck equation.