Signal-to-noise ratio gain by stochastic resonance in a bistable system

It was shown recently that the signal-to-noise ratio (SNR) could be improved by stochastic resonance (SR) in certain monostable systems and certain systems with monotonous nonlinearity working in the nonlinear response (NLR) regime. Here we demonstrate that a simple bistable system driven by periodic pulse train and band-limited Gaussian white noise can also provide an SNR gain. We show the reasons why SNR gain had not been found in double well potential systems, despite strong efforts made during the last 15 years.